Factory Workshop Manual
Make
Chevrolet
Model
Impala Ss
Engine and year
V8-350 5.7L VIN P MFI (1995)
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This manual was submitted by
Anonymous
Date
1st January 2018
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Alarm
Module, (Vehicle Antitheft) > Component Information > Service and Repair
Alarm Module: Service and Repair
PROGRAMMING A NEW THEFT DETERRENT MODULE
IMPORTANT: Any new PASS-Key II Theft Deterrent Module will automatically program to the
resistance of the key (or interrogator setting) being used at the first ignition "ON" cycle. This can
only be done once for the life of the module.
New modules are unprogrammed. Before the system will function properly after a new module has
been installed, it must be programmed to the code that matches the customer1s keys.
Programming a new module is very simple:
1. Install the new, unprogrammed module. 2. Insert one of the customer's keys in the ignition lock
cylinder and turn it to the "ON" position. It's a good idea to start the Engine at this time to
verify system operation.
3. Observe the "PASSKEY" indicator Lamp:
^ The indicator lamp should light for about five seconds and then go out. If the wiring or contacts to
the Key Resistance Pellet or the key is defective or intermittent and a new module is installed, the
Engine will start but the "PASSKEY" indicator will flash at a rate of one flash per second until the
Ignition Switch is turned off. This indicates that the module did not program and that the system
components, wiring and contacts should be checked for a fault.
IMPORTANT: Before connecting the interrogrator to the ignition lock cylinder circuit, always verify
vehicle key code and set the code into the interrogrator using the "key code" knob. This will prevent
programming an unprogrammed module with an undesired key code.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment >
Antenna Relay > Component Information > Locations > Power Antenna Relay
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment >
Antenna Relay > Component Information > Locations > Power Antenna Relay > Page 11
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment >
Antitheft Relay > Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment >
Antitheft Relay > Component Information > Locations > Page 15
Theft Deterrent Relay Daytime Running Lamps (DRL) Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment >
Emergency Contact Module > Component Information > Technical Service Bulletins > OnStar(R) - Aftermarket Device
Interference Information
Emergency Contact Module: Technical Service Bulletins OnStar(R) - Aftermarket Device
Interference Information
INFORMATION
Bulletin No.: 08-08-46-004
Date: August 14, 2008
Subject: Information on Aftermarket Device Interference with OnStar(R) Diagnostic Services
Models: 2009 and Prior GM Passenger Car and Truck (including Saturn) 2009 and Prior HUMMER
H2, H3 Models 2009 and Prior Saab 9-7X
with OnStar(R) (RPO UE1)
This bulletin is being issued to provide dealer service personnel with information regarding
aftermarket devices connected to the Diagnostic Link Connector (DLC) and the impact to
OnStar(R) diagnostic probes and Vehicle Diagnostic e-mails.
Certain aftermarket devices, when connected to the Diagnostic Link Connector, such as, but not
limited to, Scan Tools, Trip Computers, Fuel Economy Analyzers and Insurance Tracking Devices,
interfere with OnStar's ability to perform a diagnostic probe when requested (via a blue button call)
by a subscriber. These devices also prohibit the ability to gather diagnostic and tire pressure data
for a subscriber's scheduled OnStar(R) Vehicle Diagnostic (OVD) e-mail.
These aftermarket devices utilize the Vehicles serial data bus to perform data requests and/or
information gathering. When these devices are requesting data, OnStar(R) is designed not to
interfere with any data request being made by these devices as required by OBD II regulations.
The OnStar(R) advisor is unable to definitively detect the presence of these devices and will only
be able to inform the caller or requester of the unsuccessful or incomplete probe and may in some
cases refer the subscriber/requester to take the vehicle to a dealer for diagnosis of the concern.
When performing a diagnostic check for an unsuccessful or incomplete OnStar(R) diagnostic
probe, or for concerns regarding completeness of the OnStar(R) Vehicle Diagnostic (OVD) e-mail,
verify that an aftermarket device was not present at the time of the requested probe. Regarding the
OVD e-mail, if an aftermarket device is interfering (including a Scan Tool of any type), the e-mail
will consistently display a "yellow" indication in diagnostics section for all vehicle systems except
the OnStar(R) System and Tire Pressure data (not available on all vehicles) will not be displayed
(i.e. section is collapsed). Successful diagnostic probes and complete OVD e-mails will resume
following the removal or disconnecting of the off-board device.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D >
Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules
Relay Module: Customer Interest Electrical - MIL ON/DTC's Set By Various Control Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D >
Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 28
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D >
Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 29
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D >
Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 30
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules
Relay Module: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control
Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 36
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 37
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Accessories and Optional Equipment > Relay
Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 38
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Memory Positioning
Module > Component Information > Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Power Door Lock Relay >
Component Information > Locations
Power Door Lock Relay: Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Power Door Lock Relay >
Component Information > Locations > Page 46
Base Of LH A Pillar With Power Door Locks
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Power Door Lock Relay >
Component Information > Locations > Page 47
Power Door Lock Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Power Seat Control
Module > Component Information > Locations > Driver Seat Adjuster Memory Module
Power Seat Control Module: Locations Driver Seat Adjuster Memory Module
Below Center Of Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Power Seat Control
Module > Component Information > Locations > Driver Seat Adjuster Memory Module > Page 52
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Seat Heater Control
Module > Component Information > Locations > Driver Seat Heater Control Module
Seat Heater Control Module: Locations Driver Seat Heater Control Module
Attached to seat support, under LH Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Seat Heater Control
Module > Component Information > Locations > Driver Seat Heater Control Module > Page 57
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Body and Frame > Trunk / Liftgate Relay >
Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Brakes and Traction Control > ABS Main
Relay > Component Information > Service and Repair
ABS Main Relay: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Remove ABS modulator protective cover. 3. Remove relay
from modulator. 4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Brakes and Traction Control > Electronic
Brake Control Module > Component Information > Locations
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Brakes and Traction Control > Electronic
Brake Control Module > Component Information > Locations > Page 68
Brake Pressure Modulator Valve (BPMV) (With Electronic Brake Control Module (EBCM))
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Brakes and Traction Control > Electronic
Brake Control Module > Component Information > Locations > Page 69
Electronic Brake Control Module: Description and Operation
DESCRIPTION
The EBCM is a small control computer located under the trim panel on the lefthand side of the
passenger compartment on wagon models, and on the lefthand side of the luggage compartment
on sedan models. This computer monitors the speed of each wheel and the electrical status of the
hydraulic modulator. The primary functions of EBCM are to detect wheel locking, control the brake
function while in anti-lock mode and monitor system for correct electrical operation. The EBCM also
controls the display of the ABS diagnostic trouble codes. If the EBCM detects a fault, it can disable
the ABS system and activate the ABS warning lamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Brakes and Traction Control > Electronic
Brake Control Module > Component Information > Locations > Page 70
Electronic Brake Control Module: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Disconnect EBCM electrical connector. 3. Remove two
EBCM to bracket attaching nuts, then the EBCM from the vehicle. 4. Reverse procedure to install,
perform ABS system check as described in System Diagnosis. See: Brakes and Traction
Control/Antilock Brakes /
Traction Control Systems/Testing and Inspection
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Cooling System > Radiator Cooling Fan Motor
Relay > Component Information > Locations
Radiator Cooling Fan Motor Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Cooling System > Radiator Cooling Fan Motor
Relay > Component Information > Locations > Page 75
Engine Cooling Fan Relay Primary, Secondary
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations
LH Rear Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations > Page 80
Cruise Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations > Page 81
Cruise Control Module: Description and Operation
DESCRIPTION
The module has an electronic controller and an electric stepper motor to vary the throttle with each
different cruise mode. The module is not serviceable and must be replaced as an assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations > Page 82
Cruise Control Module: Service and Repair
Fig. 36 Cruise Control Module Removal
1. Disconnect battery ground cable. 2. Disconnect electrical connector from module, Fig. 36. 3.
Disconnect cruise control cable from module, then remove bolts and screws. 4. Remove module
and plugs. 5. Remove plugs from module if a new module is being installed. 6. Reverse procedure
to install noting the following:
a. Align holes in accelerator and cruise control adjuster bracket to holes in wheel house panel and
position module on wheel house panel. b. Torque module bolts and screws to 71 ft. lbs. c. Adjust
cable, if necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - HVAC > Blower Motor Relay > Component
Information > Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - HVAC > Blower Motor Relay > Component
Information > Locations > Page 87
LO Blower Relay, Rear Defog Relay And HI Blower Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - HVAC > Compressor Clutch Relay >
Component Information > Locations
Compressor Clutch Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Courtesy Lamp Relay >
Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Daytime Running Lamp
Control Unit > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Daytime Running Lamp
Control Unit > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 99
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Daytime Running Lamp
Control Unit > Component Information > Locations > Page 100
Daytime Running Lamp Control Unit: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Daytime Running Lamp
Relay > Component Information > Diagrams
Theft Deterrent Relay Daytime Running Lamps (DRL) Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Headlamp Control
Module > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Headlamp Control
Module > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 108
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Headlamp Control
Module > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 109
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Headlamp Control
Module > Component Information > Locations > Page 110
Headlamp Control Module: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Headlamp Control
Module > Component Information > Locations > Page 111
Headlamp Control Module (C2)
C406: Body Harness To Tailgate Harness, Headlamp Automatic Control Module (C1), Remote
Control Door Lock Receiver
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Lighting and Horns > Horn Relay >
Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Power and Ground Distribution > Convenience
Center <--> [Relay Box] > Component Information > Locations > Convenience Center
Convenience Center: Locations Convenience Center
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Power and Ground Distribution > Convenience
Center <--> [Relay Box] > Component Information > Locations > Convenience Center > Page 120
Behind LH I/P, Left Of Brake Pedal Bracket
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Power and Ground Distribution > Convenience
Center <--> [Relay Box] > Component Information > Locations > Convenience Center > Page 121
Under I/P
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Power and Ground Distribution > Convenience
Center <--> [Relay Box] > Component Information > Locations > Convenience Center > Page 122
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Power and Ground Distribution > Convenience
Center <--> [Relay Box] > Component Information > Locations > Page 123
Convenience Center: Application and ID
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage
Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory
Usage
INFORMATION
Bulletin No.: 04-06-04-054B
Date: November 18, 2010
Subject: Info - Non-GM Parts and Accessories (Aftermarket)
Models:
2011 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed
Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate
Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System).
The recent rise and expansion of companies selling non-GM parts and accessories has made it
necessary to issue this reminder to dealers regarding GM's policy on the use and installation of
these aftermarket components.
When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to
use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs,
special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the
same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty
repairs, special policy repairs or any repairs paid for by GM.
During a warranty repair, if a GM original equipment part is not available through GM Customer
Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources,
the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order
the circumstances surrounding why non-GM parts were used. The dealer must give customers
written notice, prior to the sale or service, that such parts or accessories are not marketed or
warranted by General Motors.
It should also be noted that dealers modifying new vehicles and installing equipment, parts and
accessories obtained from sources not authorized by GM are responsible for complying with the
National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed
by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design
characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully
understand that non-GM approved parts may not have been validated, tested or certified for use.
This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part
failure occurs as the result of the installation or use of a non-GM approved part, the warranty will
not be honored.
A good example of non-authorized modification of vehicles is the result of an ever increasing
supply of aftermarket devices available to the customer, which claim to increase the horsepower
and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to
one or more of the following modifications:
- Propane injection
- Nitrous oxide injection
- Additional modules (black boxes) that connect to the vehicle wiring systems
- Revised engine calibrations downloaded for the engine control module
- Calibration modules which connect to the vehicle diagnostic connector
- Modification to the engine turbocharger waste gate
Although the installation of these devices, or modification of vehicle components, can increase
engine horsepower and torque, they may also negatively affect the engine emissions, reliability
and/or durability. In addition, other powertrain components, such as transmissions, universal joints,
drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the
installation of these devices.
General Motors does not support or endorse the use of devices or modifications that, when
installed, increase the engine horsepower and torque. It is because of these unknown stresses,
and the potential to alter reliability, durability and emissions performance, that GM has adopted a
policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining
warranty coverage, to the powertrain and driveline components whenever the presence of a
non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is
subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or
06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for
calibration verification.
These same policies apply as they relate to the use of non-GM accessories. Damage or failure
from the use or installation of a non-GM accessory will not be covered under warranty. Failure
resulting from the alteration or modification of the vehicle, including the cutting, welding or
disconnecting of the vehicle's original equipment parts and components will void the warranty.
Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal
inquiry at either the local, state or federal level that
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Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 130
results from the alteration or modification of a vehicle using non-GM approved parts or accessories.
Dealers should be especially cautious of accessory companies that claim the installation of their
product will not void the factory warranty. Many times these companies have even given direction
on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from
finding out that is has been installed.
Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada
by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair
is to be made on the vehicle, even with the installation of such non-GM approved components, the
customer is to be made aware of General Motors position on this issue and is to sign the
appropriate goodwill documentation required by General Motors.
It is imperative for dealers to understand that by installing such devices, they are jeopardizing not
only the warranty coverage, but also the performance and reliability of the customer's vehicle.
Disclaimer
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 131
Engine Control Module: Technical Service Bulletins PROM - Reprogram Using Off Board Program
Adapter
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 73-65-13
Date: March, 1997
INFORMATION
Subject: Reprogramming Capability using the Off Board Programming Adapter
Models: 1993-97 Passenger Cars and Trucks (Applicable Reprogrammable Vehicles)
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 132
The General Motors vehicles contain Electronically Reprogrammable Devices (i.e. PCM, VCM,
ECM). These vehicles cannot be programmed through PROM replacement, however service
programming capability is available through the Tech 1/1A, Tech 2 and Techline terminals via
direct or remote programming.
The Environmental Protection Agency (EPA) has requested that all new vehicle manufacturers
ensure their dealers/retailers are aware that they are responsible for providing customers access to
reprogramming services at a reasonable cost and in a timely manner.
Although programming of controllers has become a common service practice at GM
dealers/retailers, the EPA has received reports from consumers and the aftermarket repair industry
that they were unable to purchase a new (programmed) Electronically Reprogrammable Device
(ERD) over-the-counter. As a result, on August 1, 1995, the Federal Government issued a
regulation requiring all manufacturers to make available reprogramming to the independent
aftermarket by December 1, 1997.
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 133
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 134
Today, the Off Board Programming Adapter (OBPA) is used to reprogram ERD's sold
over-the-counter. For all practical purposes, the OBPA takes the place of the vehicle when the
vehicle is not available.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 135
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 136
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 137
The list of dealerships/retailers currently own the OBPA (see Attachments 1 - 3). These locations
are equipped to provide over-the-counter preprogrammed ERD's. The hardware required to
perform reprogramming in addition to the OBPA is a Techline terminal, Tech 1/1A and associated
cables and adapters. THE TECH 2 SHOULD NOT BE USED WITH THE OBPA AT THIS TIME
BECAUSE OF INADEQUATE OBPA GROUNDING.
The current OBPA can support reprogramming on all late model General Motor's vehicles except:
^ Premium V-8's
^ 1996 Diesel Truck
^ Cadillac Catera
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 138
^ All 1997 programmable vehicles (requires use of the Tech 2)
A modification to the OBPA is being offered by Kent-Moore to support these additional vehicles and
to allow reprogramming using the Tech 2. The revisions to the OBPA for the Tech 2 is very
important as the Tech 2 is the only tool used for service programming for 1997 and future vehicles.
To have the modifications performed, contact Kent-Moore at (800) 345-2233. The revisions (part
number J 41207 REV-C) are free of charge for GM dealerships/retailers.
A dealership/retailer can purchase the OBPA by contacting Kent-Moore (part number J 41207-C).
Support on how to use the OBPA is provided by the Techline Customer Support Center (TCSC) at
(800) 828-6860 (English) or (800) 503-3222 (French).
If you need to purchase an OBPA and/or cable, contact Kent-Moore at (800) 345-2233. The OBPA
retails for $695.00 (includes all revisions 1-4) under part number J 41207-C.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Page 139
Engine Control Module: Specifications
Powertrain Control Module (PCM)
..............................................................................................................................................................
3 Nm (26 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Locations > Component
Locations
PCM Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Locations > Component
Locations > Page 142
Engine Control Module: Connector Locations
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Locations > Component
Locations > Page 143
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Locations > Component
Locations > Page 144
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Locations > Component
Locations > Page 145
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Diagrams > Diagram
Information and Instructions
Engine Control Module: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Diagrams > Diagram
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Diagrams > Diagram
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Diagrams > Diagram
Information and Instructions > Page 150
Fig.1-Symbols (Part 1 Of 3)
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Modules - Computers and Control Systems > Engine Control Module > Component Information > Diagrams > Diagram
Information and Instructions > Page 151
Fig.2-Symbols (Part 2 Of 3)
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Information and Instructions > Page 152
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Engine Control Module: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Engine Control Module: Connector Views
Powertrain Control Module (PCM): A
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Powertrain Control Module (PCM): B
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Powertrain Control Module (PCM): C
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Powertrain Control Module (PCM): D
Pinout Information
PCM Connectors
CAUTION: Do not backprobe Powertrain Control Module (PCM) connectors! The connectors are
sealed for operation in an underhood environment. Backprobing may damage the seal which could
eventually cause the connector to fail due to corrosion.
This information applies to the PCM connector charts in the next four images. These charts may be
used with the J 39700-A breakout box in conjunction with J 39700-110 and J 39700-140 cables
and high impedance digital multimeter J 39200 to obtain voltage present for each circuit listed.
Install the
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breakout box between the PCM connectors and the PCM. The breakout box PIN numbers
correspond with the PCM connector PIN numbers. Voltage may vary slightly, but should be very
close. Certain exceptions are called out in the chart legend below.
The following conditions must be met before checking typical voltages:
Key "ON":
^ DVM negative (black) lead connected to a known good ground.
^ Scan tool "NOT" installed.
^ All accessories "OFF."
^ Battery fully charged.
Engine Running:
^ All conditions listed above.
^ Engine at normal operating temperature.
^ Engine at idle/closed throttle/operating in "Closed Loop."
^ In park or neutral.
CHART LEGEND
(1) Less than .5 volt when system enabled. (2) Battery voltage for first two seconds with ignition
"ON." (3) Varies. (4) Varies with temperature. (5) Battery voltage when in gear. (6) Less than .5 volt
with brake pedal applied. (7) Battery voltage with A/C "ON." (8) Varies with altitude. (9) Less than
.5 volt with high power steering load. (*) Less than .5 volt.
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Connector "A"
RED
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Connector "B"
BLACK
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Connector "C"
GREY/CLEAR
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Connector "D"
BLUE
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Engine Control Module: Description and Operation
PCM Connectors
The Powertrain Control Module (PCM) is the control center of the fuel injection system. It
constantly looks at the information from various sensors and controls the systems that affect
vehicle performance. The PCM also performs a diagnostic function check of the system. It can
recognize operational problems and alert the driver through the Malfunction Indicator Lamp (MIL)
"Service Engine Soon" and store Diagnostic Trouble Code(s) (DTC) which identify the problem
areas to aid the technicians making repairs.
The PCM supplies 5 or 12 volts to power various sensors or switches. This is done through
resistances in the PCM which are so high in value that a test light will not light when connected to
the circuit. In some cases, even an ordinary shop voltmeter will not give an accurate reading
because its resistance is too low. Therefore, the use of a 10 megohm input impedance digital
voltmeter (J 39200) is required to assure accurate voltage readings.
Refer to Computers and Controls / System Diagnosis / Flow of Diagnosis / "Strategy Based
Diagnostics" for more information on using the diagnostic function of the PCM.
MEMORY
There are three types of memory storage within the PCM: Read Only Memory (ROM), Random
Access Memory (RAM) and Electrically Erasable Programmable Read Only Memory (EEPROM).
ROM Read Only Memory (ROM) is a permanent memory that is physically soldered to the circuit
boards within the PCM. The ROM contains the overall control programs. Once the ROM is
programmed, it cannot be changed. The ROM memory is non-erasable, and does not need power
to be retained.
RAM Random Access Memory (RAM) is the microprocessor "scratch pad." The processor can
write into, or read from this memory as needed. This memory is erasable and needs a constant
supply of voltage to be retained. If the voltage is lost, the memory is lost.
EEPROM Electrically Erasable Programmable Read Only Memory (EEPROM) is a permanent
memory that is physically soldered to the circuit boards within the PCM. The EEPROM contains the
overall control algorithms. The EEPROM can be reprogrammed by using the Tech 1 scan tool or
other Decline terminal/equipment.
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Component Tests and General Diagnostics
Engine Control Module: Component Tests and General Diagnostics
To display diagnostic trouble codes, use a Tech 1 (or equivalent scanner). Grounding the DLC will
NOT flash Diagnostic Trouble Code(s) (DTC), but will enable most outputs when the ignition is
"ON" engine "OFF." Grounding the Data Link Connector (DLC) while the engine is running will
cause the Malfunction Indicator Lamp (MIL) to flash to indicate "Open" or "Closed Loop. This is
referred to as Field Service Mode."
To clear the DTCs from memory use the Tech 1 or:
^ ignition "OFF."
^ Disconnect the # 2 fuse (located in the underhood electrical center) for 30 seconds.
Since the Powertrain Control Module (PCM) can have a failure which may affect only one circuit,
following the diagnostic procedures in this section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections or PCM is the cause of a problem and the
PCM is replaced the Knock Sensor (KS) module must be transferred to the new PCM and the new
PCM must then be programmed. If this does not correct the problem, one of the following may be
the reason:
^ There is a problem with the PCM terminal connections. The diagnostic chart will say PCM
connections or PCM. The terminals may have to be removed from the connector in order to check
them properly.
^ The problem is intermittent. This means that the problem is not present at the time the system is
being checked. In this case. Refer to Diagnosis by Symptom and make a careful physical
inspection of all portions of the system involved.
^ Shorted solenoid, relay coil, or harness. Solenoids and relays are turned "ON" and "OFF" by the
PCM using internal electronic switches called
"drivers."
A shorted solenoid, relay coil, or PCM harness will not damage the PCM but will cause the
component to be inoperative.
J 34636 or BT-8405 testers or equivalent provide a fast accurate means of checking for a shorted
coil or a short to battery voltage.
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Engine Control Module: Service and Repair
Removal
Hardware Removal
NOTE: To prevent internal Powertrain Control Module (PCM) damage, the ignition must be "OFF",
when disconnecting or reconnecting power to the PCM.
Remove or Disconnect:
1. Disconnect negative battery cable 2. Disconnect PCM mounting hardware 3. Disconnect PCM
electrical connectors 4. Remove PCM from engine compartment
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PCM With Knock Sensor Module
5. Remove PCM access cover
Removing Knock Sensor Module From PCM
6. Remove knock sensor module from PCM
Install or Connect:
1. Install knock sensor module and access cover 2. Install PCM in vehicle 3. Connect PCM
electrical connectors 4. Connect PCM mounting hardware 5. Connect negative battery cable
EEPROM Programming
CAUTION:The software/calibration used for PCM reprogramming must match the vehicle
application, or improper operation and/or damage may
occur.
^ Ensure battery is charged
^ Turn ignition "ON"
^ Ensure connections to the Data Link Connector (DLC) and battery/cigar lighter are secure
^ Follow the most current Decline terminal/equipment instructions
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PCM Reprogramming Failure
^ Check PCM connections
^ Check Decline terminal/equipment for latest software version
^ Repeat reprogramming procedures. If it fails again, replace the PCM. The replacement PCM
must be programmed.
PCM Functional Check
^ Refer to System Diagnosis / Diagnostic System Check.
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PCM With Knock Sensor Module
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Knock Sensor Module: Service and Repair
PCM With Knock Sensor Module
Removing Knock Sensor Module From PCM
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Powertrain Control Module (PCM) from mounting bracket (refer to
PCM removal). 3. Knock sensor (KS) module access cover. 4. Knock sensor module.
INSTALL OR CONNECT
NOTICE: To prevent possible electrostatic discharge damage to the PCM and KS module, Do Not
touch the connector pins or soldered components on the circuit board.
1. Knock senor module. 2. Access cover. 3. PCM to mounting bracket (refer to PCM installation). 4.
Negative battery cable.
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Modules - Emission Control Systems > Air Injection Pump Relay > Component Information > Locations
Air Injection Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
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Air Injection Pump Relay: Description and Operation
Chart C-6
The Powertrain Control Module (PCM) controls operation of the electric air pump relay which in
turn controls air availability to the air injection system. The PCM completes the ground to the coil
side of the relay. The relay in turn activates the electric air pump and the integral stop valve.
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Fuel Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
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Fuel Pump Relay: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Fuel Pump Relay: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Modules - Fuel Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information
and Instructions > Page 239
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Fuel Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Page 240
Fuel Pump Relay: Description and Operation
When the ignition switch is turned to the "ON" position (before engaging starter), the energizes the
fuel pump relay for two seconds causing the fuel pump to pressurize the fuel system. If the
Powertrain Control Module (PCM) does not receive ignition reference pulses (engine cranking or
running) within two seconds, it shuts "OFF" the fuel pump relay, causing the fuel pump to stop.
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Fuel Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Page 241
Fuel Pump Relay: Service and Repair
Fuel Pump (Circuit Opening) Relay
REMOVE OR DISCONNECT
1. Underhood (U/H) electrical center cover. 2. Fuel pump relay.
INSTALL OR CONNECT
1. Fuel pump relay. 2. Underhood (U/H) electrical center cover.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Ignition System > Ignition Control Module > Component Information > Specifications
Ignition Control Module: Specifications
Ignition Coil Assembly Bolt / Screw
...........................................................................................................................................................
25 Nm (18 lb ft.)
Ignition Coil Assembly Stud .................................................................................................................
...................................................... 25 Nm (18 lb ft.)
Ignition Coil Module Bolt / Screw
.............................................................................................................................................................
1.7 Nm (15 lb in.)
Replacement Coil to-Bracket Bolt / Screw
................................................................................................................................................. 2.8 Nm
(25 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Ignition System > Ignition Control Module > Component Information > Locations > Ignition Coil Module Connector
Engine Left Side Upper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Ignition System > Ignition Control Module > Component Information > Locations > Ignition Coil Module Connector
> Page 248
Ignition Control Module: Locations Ignition Module
Ignition Coil
Ignition Coil And Ignition Control Module
The Ignition Control Module is located on the ignition coil bracket assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Ignition System > Ignition Control Module > Component Information > Locations > Page 249
Ignition Control Module: Description and Operation
Ignition Coil And Module Assembly
Ignition Coil And Module
The ignition coil/ignition control module assembly provides spark to the distributor assembly, timed
by signals from the ECM. Power (B+) for the ignition coil primary circuit and the ignition control
module is supplied by the ignition switch. The ECM combines the camshaft position information
supplied by the distributor with other system parameters and calculates the required spark advance
and coil dwell. The ECM signals the ignition control module, which turns on the primary current to
the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When
the primary current flow stops, high voltage induced in the ignition coil secondary winding becomes
the spark voltage for the spark plug. The spark voltage is delivered to the distributor assembly
through the coil output (secondary) wire, and then directed to the proper spark plug connector by
the distributor rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Ignition System > Ignition Control Module > Component Information > Locations > Page 250
Ignition Control Module: Service and Repair
Ignition Coil
Ignition Coil And Ignition Control Module
Numbers used below refer to image caption.
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Four-terminal Powertrain Control
Module (PCM) connector at ignition coil module. 3. Ignition coil wiring connectors. 4. Ignition coil
harness.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Powertrain Management > Relays and
Modules - Ignition System > Ignition Control Module > Component Information > Locations > Page 251
5. Studs (5). 6. Ignition coil / Ignition Control Module assembly (8).
^ Do not wipe silicone grease from bottom of ignition coil assembly (8) if it is to he reinstalled.
DISASSEMBLE
1. Coil (10) from brackets (13 and 14) by drilling out rivets (9). 2. Bolts/screws (12). 3. Ignition
control module (11).
NOTICE: If a new ignition coil assembly is to be installed, a package of silicone grease will be
included in the box. This grease is necessary for ignition coil assembly cooling.
ASSEMBLE
1. Spread silicone grease on metal face of ignition control module (11) and on bracket (13) where it
seats, and position ignition control module (11)
to bracket (13).
2. Bolts / screws (12).
Tighten ^
Bolts / screws (12) to 1.7 Nm (15 lb in.).
3. Coil (10) to brackets (13 and 14) using bolts / screws provided with replacement coil (10).
Tighten ^
Bolts / screws to 2.8 Nm (25 lb in.).
INSTALL OR CONNECT
1. Spread silicone grease on metal mounting face of ignition coil bracket (14) if necessary, and
position ignition coil / Ignition Control module
assembly (8) to cylinder head assembly.
2. Studs (5).
Tighten ^
Studs (5) to 25 Nm (18 lb ft.).
3. Ignition coil harness. 4. Ignition coil wiring connectors. 5. Four terminal PCM connector to
ignition coil module.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > System Component Locations
Description
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > System Component Locations > Page 257
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > Page 258
Inflatable Restraint Diagnostic Energy Reserve (With Sensor) Module (SDM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > Page 259
Air Bag Control Module: Description and Operation
DESCRIPTION
The Sensing and Diagnostic Module (SDM) performs several system functions. These functions
include energy reserve, air bag deployment, malfunction detection, malfunction diagnosis, driver
notification, frontal crash detection and frontal crash recording.
OPERATION
The SDM contains a sensing device which converts vehicle velocity changes to an electrical signal.
The electrical signal generated is processed by the SDM and then compared to a value stored in
memory. When the generated signal exceeds the stored value, additional signals are compared to
signals stored in memory. When two of the generated signals exceed the stored values or when
one of the generated signals exceeds the stored value and the forward discriminating sensor
closes, the SDM will cause current to flow through the inflator modules deploying the air bags.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Steering and Suspension > Relays and
Modules - Steering > Steering Control Module > Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Steering and Suspension > Relays and
Modules - Steering > Steering Control Module > Component Information > Locations > Page 265
Power Steering Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Steering and Suspension > Relays and
Modules - Suspension > Compressor/Pump Relay, Suspension Control > Component Information > Description and
Operation
Compressor/Pump Relay: Description and Operation
DESCRIPTION
The compressor relay is controlled by the height sensor and completes the 12-volt circuit to the
compressor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Windows and Glass > Heated Glass Element
Relay > Component Information > Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Relays and Modules > Relays and Modules - Windows and Glass > Heated Glass Element
Relay > Component Information > Locations > Page 274
LO Blower Relay, Rear Defog Relay And HI Blower Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Door Lock
Switch > Component Information > Locations > Component Locations
Power Door Lock Switch: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Door Lock
Switch > Component Information > Locations > Component Locations > Page 281
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Door Lock
Switch > Component Information > Locations > Component Locations > Page 282
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Door Lock
Switch > Component Information > Locations > Page 283
Power Door Lock Switch RH And LH Front
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Mirror Switch >
Component Information > Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Locations > Component Locations
Power Seat Switch: Component Locations
Driver Seat Switch Pod
Bottom Of driver Seat, outboard Side
Passenger Seat Switch Pod
Part of bottom Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Locations > Component Locations > Page 291
Power Seat Switch: Connector Locations
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Locations > Component Locations > Page 292
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Diagrams > LH and RH Lumbar Switch Assembly
C312 & C313: LH And RH Lumbar Switch Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Diagrams > LH and RH Lumbar Switch Assembly > Page 295
Power Seat Switch LH And RH
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Seat Heater Switch >
Component Information > Locations > Driver Seat Heater Switch
Seat Heater Switch: Locations Driver Seat Heater Switch
LH side of Driver's Seat Cushion
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Seat Heater Switch >
Component Information > Locations > Driver Seat Heater Switch > Page 300
Seat Heater Switch: Locations Passenger Seat Heater Switch
LH side of Passenger Seat Cushion
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Seat Memory Switch >
Component Information > Locations
Seat Memory Switch: Locations
LH Front door on armrest
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch
> Component Information > Locations > Component Locations
Trunk / Liftgate Switch: Component Locations
Trunk Lid With Pull-Down
Back View Of LH Instrument Panel
Rear Compartment Lid Enable Switch
Mounted on I/P Compartment
Rear Luggage Compartment With Pull-Down
Rear Compartment Lid Pull-Down Striker Switch
Attached to Rear Compartment Lid Pulldown Actuator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch
> Component Information > Locations > Component Locations > Page 308
Rear Compartment Lid Pull-Down Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch
> Component Information > Locations > Component Locations > Page 309
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch
> Component Information > Locations > Page 310
Rear Glass Interlock/Push Button Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Brake Fluid
Level Sensor/Switch > Component Information > Description and Operation
Brake Fluid Level Sensor/Switch: Description and Operation
OPERATION
This sensor mounted on the master cylinder will activate the Brake Warning lamp if a low brake
fluid level is detected. The lamp will turn off once the fluid level is corrected.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Brake Fluid
Pressure Sensor/Switch > Component Information > Locations
LH Rear Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Brake Fluid
Pressure Sensor/Switch > Component Information > Locations > Page 318
Brake Fluid Pressure Sensor/Switch: Description and Operation
Fig. 3 Pressure Differential Valve & Brake Warning Lamp Switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Brake Fluid
Pressure Sensor/Switch > Component Information > Locations > Page 319
Fig. 4 Dual Master Cylinder W/Built In Warning Lamp Switch.
DESCRIPTION
In Fig. 3, as pressure falls in one system, the other system's normal pressure forces the piston to
the inoperative side, contacting the switch terminal, causing the warning lamp on the instrument
panel to glow.
In Fig. 4 shows the switch mounted directly in the master cylinder assembly. Whenever there is a
specified differential pressure, the switch piston will activate the brake failure warning switch and
cause the brake warning lamp to glow.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Parking
Brake Warning Switch > Component Information > Locations > Park Brake Indicator Switch
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Parking
Brake Warning Switch > Component Information > Locations > Park Brake Indicator Switch > Page 324
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front
Wheel Speed Sensor: Locations Wheel Speed Sensor Lead, Front
LH Rear Engine Compartment
LH Front Frame Rail
RH Front Frame Rail
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 329
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 330
Wheel Speed Sensor: Locations Wheel Speed Sensor, Rear
LH Rear Frame Rail (Without Automatic Level Control)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 331
Antilock Brake System Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Locations > Page 332
Wheel Speed Sensor: Description and Operation
DESCRIPTION
These sensors transmit wheel speed information to the EBCM using a small amount of AC voltage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor
Wheel Speed Sensor: Service and Repair Left Front Wheel Speed Sensor
REPLACEMENT
1. Raise and support vehicle. 2. Disconnect wheel speed sensor harness connector and sensor
assembly connector from clip. 3. Disconnect speed sensor connector from harness connector. 4.
Remove sensor bracket attaching bolt from frame rail. 5. Disconnect wheel speed sensor assembly
harness with grommets from brackets and combination valve brake pipe clip. Note position of
grommets and harness for installation reference.
6. Remove speed sensor retaining bolt, then the speed sensor from steering knuckle. 7. Reverse
procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the knuckle and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor > Page 335
Wheel Speed Sensor: Service and Repair Rear Axle Speed Sensor
1. Raise and support vehicle.
2. Unclip sensor assembly connector and differential sensor connector, then separate the
connectors.
3. Disconnect speed sensor harness assembly wiring harness with gromments from sensor
bracket. Note position of grommets and harness for installation reference.
4. Remove sensor attaching bolt, then the sensor from the vehicle.
5. Reverse procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the axle housing and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Brakes and Traction Control > Wheel
Speed Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor > Page 336
Wheel Speed Sensor: Service and Repair Right Front Wheel Speed Sensor
REPLACEMENT
1. Disconnect forward lamp harness wheel speed sensor connector and wheel speed sensor
assembly connector from clip. 2. Disconnect forward lamp harness connector from wheel speed
sensor connector. 3. Raise and support vehicle. 4. Remove sensor bracket attaching bolt from
frame rail. 5. Remove sensor assembly harness with grommets from brackets. Note position of
grommets and harness for assembly reference. 6. Remove sensor retaining bolt, then the sensor
from vehicle. 7. Reverse procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the knuckle and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Coolant Level Sensor >
Component Information > Locations
Rear Side Radiator Support, Coolant Fans
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Engine - Coolant
Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information >
Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Engine - Coolant
Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information >
Specifications > Page 345
Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Engine - Coolant
Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information >
Specifications > Page 346
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Engine - Coolant
Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information >
Specifications > Page 347
Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Engine - Coolant
Temperature Sensor/Switch > Radiator Cooling Fan Temperature Sensor / Switch > Component Information > Locations
Radiator Cooling Fan Temperature Sensor / Switch: Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cooling System > Engine - Coolant
Temperature Sensor/Switch > Temperature Sensor (Gauge) > Component Information > Locations
Temperature Sensor (Gauge): Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Cruise Control > Brake Switch (Cruise
Control) > Component Information > Service and Repair
Brake Switch (Cruise Control): Service and Repair
Fig. 3 Cruise Control Release Switch & Stop Lamp Switch Assemblies
1. Disconnect electrical connectors, then remove release switch and stop lamp switch assemblies
from retainers, Fig. 3. 2. Remove retainers from bracket. 3. Reverse procedure to install. Adjust as
outlined.
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Component Information > Locations > Component Locations
Upper LH Side Of Steering Column
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Component Information > Locations > Component Locations > Page 362
Upper LH Side Of Steering Column
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Component Information > Locations > Component Locations > Page 363
Upper LH Side Of Steering Column
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Component Information > Locations > Page 364
C215: Cruise Control Switch
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Cruise Control Switch: Description and Operation
Fig. 3 Cruise Control Release Switch & Stop Lamp Switch Assemblies
DESCRIPTION
The release switch and stop lamp switch cannot be adjusted until after the brake booster pushrod
is assembled to brake pedal assembly. Refer to Fig. 3 when performing this procedure.
OPERATION
1. Depress brake pedal and insert release switch and stop lamp switch assembly into retainers until
fully seated. 2. Slowly release brake pedal back to its original position. Release switch and stop
lamp switch assemblies will move within retainers to their
adjusted position.
3. The following brake pedal travel distances can be used to check for properly adjusted release
switch and stop lamp switch assemblies:
a. Release switch and stop lamp switch assemblies contacts must be open at 1/8-1/2 inch brake
pedal travel, measured at centerline of brake pedal
pad.
b. Nominal actuation of stop lamp switch contacts is about 3/16 inch after cruise switch control
contacts close.
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Cruise Control Switch: Service and Repair
The engagement switch is not serviceable. The complete turn signal, headlamp dimmer switch,
cruise control actuator and windshield wiper/washer must be replaced as an assembly. 1.
Disconnect battery ground cable. 2. Remove steering column access cover, then disconnect
electrical connector. Ensure windshield wiper switch is in Off position. 3. Remove lever assembly
by pulling straight out. 4. Reverse procedure to install.
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Sensor/Transducer - Cruise Control > Component Information > Description and Operation
Vehicle Speed Sensor/Transducer - Cruise Control: Description and Operation
DESCRIPTION
The Vehicle Speed Sensor (VSS) buffer receives a signal from the VSS (permanent magnet
generator) indicating vehicle speed. The buffer processes the signal which is then sent to the
Engine Control Module (ECM), cruise control module and speedometer.
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Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Engine > Oil Level Sensor > Component
Information > Locations
Engine, Left Side Lower
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Oil Level Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oil Level Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Component Information > Locations
Rear Of Engine
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Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
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Rear Of Engine
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Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
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Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Fuel Pump Switch/Engine Oil Pressure Gage Sensor
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Fuel Pump Relay Circuit
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Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Engine > Oil Pressure Switch (For Fuel
Pump) > Component Information > Diagrams > Page 452
Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Air Conditioning Switch >
Component Information > Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Ambient Temperature Sensor /
Switch HVAC > Component Information > Locations > Inside Air Temperature Sensor
Ambient Temperature Sensor / Switch HVAC: Locations Inside Air Temperature Sensor
Instrument Panel Carrier, above Glove Box.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Ambient Temperature Sensor /
Switch HVAC > Component Information > Locations > Inside Air Temperature Sensor > Page 461
Ambient Temperature Sensor / Switch HVAC: Locations Outside Air Temperature Sensor
Attached to Hood Latch Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Blower Motor Switch >
Component Information > Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Blower Motor Switch >
Component Information > Locations > Page 465
Heater And A/C Blower Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Refrigerant Pressure Sensor /
Switch, HVAC > Component Information > Locations > A/C Compressor Pressure Cycling Switch
Refrigerant Pressure Sensor / Switch: Locations A/C Compressor Pressure Cycling Switch
Engine Harness/U/Hood Electrical Center, Right Side
Attached to A/C accumulator, RH rear of Engine Compartment
RH Rear Engine Compartment attached to A/C Accumulator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Refrigerant Pressure Sensor /
Switch, HVAC > Component Information > Locations > A/C Compressor Pressure Cycling Switch > Page 470
Refrigerant Pressure Sensor / Switch: Locations A/C Refig Press Sensor
Component Location - Pictorial View
In High Pressure Line, below Coolant Reservoir
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - HVAC > Solar Sensor, HVAC >
Component Information > Locations
Solar Sensor: Locations
Near center of I/P Upper Trim Pad (in Defroster Grille)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Dimmer Switch >
Component Information > Technical Service Bulletins > IP Dimmer Control - Proper Setting
Dimmer Switch: Technical Service Bulletins IP Dimmer Control - Proper Setting
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-42-009
Date: November, 1999
INFORMATION
Subject: Proper Setting of I/P Dimmer Control to View PRNDL Display with Automatic Headlamp
Control
Models: 2000 and Prior All Passenger Cars and Trucks With Automatic Headlamp Control and
Electronic PRNDL Display
Under certain conditions, if the instrument panel dimmer control is turned relatively low, the PRNDL
will not be visible until the automatic headlamp control turns the headlamps off and the daytime
running lamps (DRL) are turned back on. Such a condition may be if the vehicle is first started in an
environment where the headlamp control turns on the headlamps and then the vehicle is driven out
into a brighter environment (for example, when a vehicle is backed out of a dark garage into the
bright sunlight).
This condition is normal and any repair attempt will not be successful. Demonstrate this condition
to the customer using the service lane and then turn the instrument panel dimmer control to a
higher setting. This will enable the driver to see the PRNDL display
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Dimmer Switch >
Component Information > Locations > Component Locations
Dimmer Switch: Component Locations
Lower LH Side Of Steering Column
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Dimmer Switch >
Component Information > Locations > Component Locations > Page 481
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Dimmer Switch >
Component Information > Locations > Page 482
Dimmer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Dimmer Switch >
Component Information > Locations > Page 483
Dimmer Switch: Service and Repair
Fig. 13 Column Mounted Dimmer Switch Installation
1. Disconnect battery ground cable. 2. Remove instrument panel lower trim and on models with
A/C, remove A/C duct extension at column. 3. Disconnect shift indicator from column and remove
toe-plate cover screws. 4. Remove two nuts from instrument panel support bracket studs and lower
steering column, resting steering wheel on front seat. 5. Remove dimmer switch retaining screws,
then the switch. Tape actuator rod to column and separate switch from rod. 6. Reverse procedure
to install. To adjust switch, depress dimmer switch slightly and install a 3/32 inch twist drill to lock
switch to the body, Fig. 13.
Force switch upward to remove lash between switch and pivot, then remove tape from actuator
rod. Remove twist drill and check for proper operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 488
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 489
Door Switch: Locations Door Jamb Switch, RH Front
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 490
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 491
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Fuel Gauge Sender >
Component Information > Locations
Fuel Gauge Sender: Locations
Mounted on Fuel Tank, Part of Fuel Tank Unit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Fuel Gauge Sender >
Component Information > Locations > Page 495
Fuel Pump/Sender Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Parking Brake
Warning Switch > Component Information > Locations > Park Brake Indicator Switch
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Instrument Panel > Parking Brake
Warning Switch > Component Information > Locations > Park Brake Indicator Switch > Page 500
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Ambient Light
Sensor > Component Information > Locations
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Backup Lamp
Switch > Component Information > Locations
Backup Lamp Switch: Locations
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Backup Lamp
Switch > Component Information > Locations > Page 508
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Brake Light Switch >
Component Information > Locations
Brake Light Switch: Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Brake Light Switch >
Component Information > Locations > Page 512
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Brake Light Switch >
Component Information > Locations > Page 513
Brake Light Switch: Service and Repair
The stop light switch has a slip fit in the mounting sleeve which permits positive adjustment by
pulling the brake pedal up firmly against the stop. The pedal arm forces the switch body to slip in
the mounting sleeve bushing to position the switch properly.
1. Disconnect wires from switch and remove switch from bracket. 2. Position replacement switch in
bracket and push inward until fully seated. Brake pedal arm moves switch to correct distance on
rebound. Check if
pedal is in full return position by lifting slightly by hand.
3. Connect switch electrical connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 518
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 519
Door Switch: Locations Door Jamb Switch, RH Front
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 520
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 521
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Dimmer
Switch > Component Information > Locations
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector
Twilight Sentinel Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector > Page 529
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector > Page 530
Headlamp Switch: Locations Twilight Sentinel/Daytime Running Lamps Harness
Back View Of RH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector > Page 531
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Page 532
Headlamp Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Page 533
Headlamp Switch: Service and Repair
Fig. 7 Headlamp Switch Replacement
1. Disconnect battery ground cable. 2. Remove lower steering column trim panel attaching screws,
then pull downward to remove. 3. Through glove compartment, unsnap righthand molding. 4.
Loosen steering column support bracket to instrument panel carrier attaching bolts. Do not remove
bolts. 5. Gently lower steering column assembly. Use extreme care when lowering steering to
prevent damage to column assembly. 6. Remove lefthand trim plate to instrument panel carrier
assembly six attaching screws, then unsnap lefthand trim assembly. 7. Remove headlamp switch
attaching screws. 8. Pull switch rearward, then disconnect switch electrical connectors and remove,
Fig. 7. 9. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Horn Switch >
Component Information > Locations
Steering Wheel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Trunk Lamp Switch
> Component Information > Locations > Rear Compartment Lid Latch Switch
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Trunk Lamp Switch
> Component Information > Locations > Rear Compartment Lid Latch Switch > Page 541
Rear Luggage Compartment With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Trunk Lamp Switch
> Component Information > Locations > Rear Compartment Lid Latch Switch > Page 542
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations
Turn Signal Switch: Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 546
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 547
C210: Turn Signal Switch Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 548
Turn Signal Switch: Service and Repair
Fig. 9 Lock Plate Retaining Ring Removal
Fig. 10 Turn Signal Electrical Connector & Wiring Isolation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 549
Fig. 11 Turn Signal Switch Removal From Column Bowl
Fig. 12 Turn Signal Switch Replacement
1. Disconnect battery cable, then remove steering wheel and column to instrument panel trim
cover. 2. On models with telescoping column, remove bumper spacer and snap ring retainer. 3. On
models less telescoping column, remove cover from lock plate. 4. On all models, using a suitable
tool, compress lock plate (horn contact carrier on tilt models) and remove snap ring (C-ring on tilt
models), Fig. 9. 5. Remove lock plate, cancelling cam, upper bearing preload spring, thrust washer
and signal lever. 6. Remove turn signal lever or actuating arm screw, if equipped, or on models
with column mounted wiper switch, pull lever straight out of detent.
Depress hazard warning button, then unscrew button.
7. Pull connector from bracket and wrap upper part of connector with tape to prevent snagging
wires during removal, Fig. 10. 8. On Tilt models, position shifter housing in Low position. Remove
harness cover. 9. On models less tilt remove retaining screws and remove switch, Fig. 11 AND 12.
10. Reverse procedure to install
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Locations > Component
Locations
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Locations > Component
Locations > Page 556
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 559
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 560
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 561
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 562
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 563
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 564
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Powertrain Management > Sensors and
Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram
Information and Instructions > Page 565
Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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MAF Sensor Circuit.
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Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
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Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information > Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
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Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
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Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
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Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
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Information and Instructions
Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Intake Air Temperature Sensor: Specifications Torque Valve
Torque Valve
Induction Air Sensor 44 in.lb
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Intake Air Temperature Sensor: Locations IAT Sensor
The Intake Air Temperature (IAT) sensor is located in the air ducting, just forward of the throttle
body assembly.
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Intake Air Temperature Sensor: Locations Intake Air Temperature (IAT) Sensor
Component Location - Pictorial View
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Component Location - Pictorial View
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Diagram Information and Instructions
Intake Air Temperature Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Intake Air Temperature Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Diagram Information and Instructions > Page 696
Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Intake Air Temperature (IAT) Sensor Circuit.
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Intake Air Temperature Sensor: Description and Operation
Engine Coolant Temperature (ECT) Sensor
The Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on
temperature). It is mounted in the air intake duct. Low temperature produces a high resistance and
high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the sensor through a resistor in
the PCM and measures the voltage. The voltage will be high when the intake air is cold, and low
when the intake manifold air is hot. By measuring the voltage, the PCM knows the intake air
temperature. A failure in the IAT sensor circuit should set either a DTC 23 or DTC 25.
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Intake Air Temperature Sensor: Service and Repair
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Electrical connector. 3. Carefully remove sensor from air duct.
INSTALL OR CONNECT
1. Install sensor in engine. 2. Connect electrical connector. 3. Connect negative battery cable.
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Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
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Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
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Engine Harness/U/Hood Electrical Center, Right Side
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Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor Circuit
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Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
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Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
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Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
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> Electrical Specifications
MAP Sensor Chart
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Manifold Pressure/Vacuum Sensor: Mechanical Specifications
Manifold Absolute Pressure (MAP) Bolt
...................................................................................................................................................... 6
Nm (50 lb in.)
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Manifold Pressure/Vacuum Sensor: Locations
MAP Sensor Location
Component Location - Pictorial View
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Diagram Information and Instructions
Manifold Pressure/Vacuum Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Manifold Pressure/Vacuum Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Map Sensor Circuit.
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Manifold Pressure/Vacuum Sensor: Description and Operation
MAP Sensor
The Manifold Absolute Pressure (MAP) sensor is a pressure sensor that measures changes in
intake manifold pressure. The pressure changes as a result of engine load and speed. The MAP
sensor converts this to a voltage output.
A closed throttle on engine coastdown would produce a relatively low MAP output while a
wide-open throttle would produce a high MAP output voltage. This high output voltage is produced
because the pressure inside the manifold is the same as outside the manifold, so you measure
100% of outside air pressure. Manifold Absolute Pressure (MAP) is inversely proportional to what
you would measure on a vacuum gage. When manifold pressure is high vacuum is low. The MAP
sensor is also used to measure barometric pressure under certain conditions which allows the
Powertrain Control Module (PCM) to automatically adjust for different altitudes.
The PCM sends a 5 volt reference signal to the MAP sensor. As the manifold pressure changes the
electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage the
PCM knows the manifold pressure. The PCM uses the MAP sensor to control ignition timing. The
MAP sensor is also used for speed density fuel management. When the PCM detects a
malfunction with the Mass Air Flow (MAF) sensor circuit the PCM will default to speed density.
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Page 796
Manifold Pressure/Vacuum Sensor: Service and Repair
MAP Sensor Location
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Resonator. 3. Electrical connector. 4. Hold down bolts (2). 5. Sensor
from intake manifold.
INSTALL OR CONNECT
1. New sensor seal (lightly coated with clean engine oil). 2. Sensor into intake manifold. 3. Hold
down bolts. 4. Torque to 6 Nm (50 lb in). 5. Connect electrical connector. 6. Resonator. 7. Connect
negative battery cable.
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Oxygen Sensors - Silica Contamination
Oxygen Sensor: Technical Service Bulletins Oxygen Sensors - Silica Contamination
Model Year: 1981
Bulletin No: 81-I-37
File In Group: 60
Number: 11
Date: Feb. 81
Subject: Silica Contamination of Oxygen Sensors and Gelation of Oil.
Models Affected: All
Oxygen sensor performance can deteriorate if certain RTV silicone gasket materials are used.
Other RTV's when used with certain oils, may cause gelation of the oil. The degree of performance
severity depends on the type of RTV and application of the engine involved.
Therefore, when repairing engines where this item is involved, it is important to use either cork
composition gaskets or RTV silicone gasket material approved for such use. GMS (General Motors
Sealant) or equivalent material can be used. GMS is available through GMPD with the following
part numbers:
1052366 3 oz.
1052434 10.14 oz.
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Specifications
Oxygen Sensor Output
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Oxygen Sensor: Mechanical Specifications
Heated Oxygen Sensor (HO2S) ..........................................................................................................
......................................................... 41 Nm (30 lb ft.)
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Switches - Computers and Control Systems > Oxygen Sensor > Component Information > Locations > LH
Engine, Left Side Lower
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Lower Right Side Of Engine
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HO2S Location
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Oxygen Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oxygen Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Oxygen Sensor: Electrical Diagrams
Heated Oxygen Sensor (HO2S) Sensor Circuit.
Right Heated Oxygen Sensor Circuit.
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Oxygen Sensor: Description and Operation
HO2S Cutaway
Oxygen Sensor Element
The Heated Oxygen Sensor (HO2S) is essentially a small variable battery; it has the ability to
produce a low voltage signal that feeds information on engine exhaust oxygen content to the
Powertrain Control Module (PCM).
The PCM sends a reference signal of 450 mV. The reference signal serves to run the engine when
it is in "Open Loop" mode of operation. When the air/fuel ratio is correct the PCM displays 450 mV.
When the engine is operating with a rich air/fuel ratio, there is a reduction of free oxygen in the
exhaust stream and the oxygen voltage rises above the reference voltage.
The HO2S is constructed from a material (zirconia/platinum) that conducts electricity under certain
conditions. At operating temperature, 315°C (60o° F), the element becomes a semiconductor. A
platinum coating on the outer surface of the element stimulates further combustion of the exhaust
gases right
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at the surface and this helps keep the element up to the desired temperature. The HO2S has an
inter cavity which is filled with atmospheric (reference) air. The reference air has approximately
21% oxygen in it. In this electrical circuit this inter cavity is the positive (+) terminal. The outer
surface of the element is exposed to the exhaust gas stream. It is the negative (-) or ground
terminal. The oxygen concentration differences between the reference air and exhaust gases
produce small voltages.
A rich exhaust (excessive fuel) has almost no oxygen. When there is a large difference in the
amount of oxygen touching the inside and outside surfaces, there is more conduction, and the
sensor puts out a voltage signal above 600 mV. With lean exhaust (excessive oxygen) there is
about two percent oxygen in the exhaust. This is a smaller difference in oxygen from the outside
surfaces which results in less conduction and a voltage signal below 300 mV. The voltages are
monitored and used by the PCM to "fine tune" the air/fuel ratio to achieve the ideal mixture desired.
When the engine is running lean. the voltage drops below the reference voltage due to excess
oxygen in the exhaust stream. The HO2S provides the feedback information for the "Closed Loop"
operating mode of the fuel delivery system. The HO2S indicates to the PCM what is happening in
the exhaust. It does not cause things to happen. It is a type of gage: Low voltage output = lean
mixture = high oxygen content in exhaust; high voltage output = rich mixture = low oxygen content
in the exhaust.
An open Heated Oxygen Sensor (HO2S) circuit, should set Diagnostic Trouble Code (DTC) 13 or
63. A constant low voltage in the HO2S circuit could set a DTC 44 or 64. A constant high voltage in
the circuit should set a DTC 45 or 65. DTCs 44. 45. 64, or 65 could also be set as a result of fuel
system problems.
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Oxygen Sensor: Service and Repair
HO2S Location
CAUTION: The Heated Oxygen Sensor (HO2S) uses a permanently attached pigtail and
connector. This pigtail should not be removed from the oxygen sensor. Damage or removal of the
pigtail or connector could affect proper operation of the oxygen sensor.
^ Take care when handling the oxygen sensor. The in-line electrical connector and louvered end
must be kept free off grease, dirt or other contaminants. Also, avoid using cleaning solvents of any
type. Be careful not to subject the sensor to sharp impact.
REMOVAL:
NOTICE: The HO2S may be difficult to remove when engine temperature is below 48° C (120° F).
Excessive force may damage threads in exhaust pipe.
1. Disconnect the negative battery cable. 2. Raise vehicle. 3. Disconnect the oxygen sensor
electrical connector. 4. Carefully remove the oxygen sensor.
INSTALLATION:
NOTICE: A special anti-seize compound is used on the oxygen sensor threads. The compound
consists of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will
remain, making the sensor easier to remove. New or service sensors will already have the
compound applied to the threads. If a sensor is removed from an engine, and, if for any reason it is
to be reinstalled, the threads must have anti-seize compound applied before reinstallation.
1. Coat the threads of the HO2S with anti-seize compound P/N 5613695, or equivalent if
necessary. 2. Install the sensor in the engine, and tighten to 41 Nm (30 ft lb). 3. Connect the
electrical connector. 4. Lower vehicle. 5. Connect the negative battery cable.
NOTICE: The system has a learning ability which allows it to make corrections for minor variations
in the fuel system to improve driveability. When the battery is disconnected the computer's memory
is cleared and the learning process has to begin all over again. A change may be noticed in the
driving performance of the vehicle. To reset the vehicles learning ability, make sure the engine is at
operating temperature and operate the vehicle at part throttle, moderate acceleration, and idle
conditions, until normal performance returns.
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Left Front Of Engine
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Diagram Information and Instructions
Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Power Steering Pressure Switch Circuit.
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Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
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Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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Throttle Position Sensor: Locations
Component Location - Pictorial View
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Component Location - Pictorial View
Throttle Body
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Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Throttle Position Sensor Circuit.
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Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
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RH Side Of Steering Column
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Locations > Component Locations > Page 929
RH Side Of Steering Column
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Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Rear Of Transmission
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Vehicle Speed Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Vehicle Speed Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Vehicle Speed Sensor: Description and Operation General Description
Vehicle Speed Sensor (2WD)
The Vehicle Speed Sensor (VSS) is a pulse counter type input that informs the Powertrain Control
Module (PCM) how fast the vehicle is being driven. The VSS system uses an inductive sensor
mounted in the tail housing of the transmission and a toothed reluctor wheel on the tail shaft. As
the reluctor rotates, the teeth alternately interfere with the magnetic field of the sensor creating an
induced voltage pulse.
The VSS produces an AC voltage signal that increases with vehicle speed. The PCM processes
this signal and sends it to the instrument panel, EVO module, chime module and cruise control
module on CKT 817. A malfunction in the VSS system could set Diagnostic Trouble Code (DTC) 24
or DTC 72.
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Vehicle Speed Sensor: Description and Operation Circuit Operation
The Speed Sensor Circuit consists of a magnetic type sensor and wiring. Gear teeth pressed on
the Transmission Output Shaft induce an alternating current in the sensor. This sensor generates a
sine wave output with a frequency proportional to vehicle speed. The Powertrain Control Module
(PCM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses
per mile at the DK GRN/WHT wire (CKT 817) which feeds the Turn Signal Alarm, Power Steering
Control Module, Instrument Cluster, Cruise Control Module and Radio (Chev only).
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Initial Inspection and Diagnostic Overview
Vehicle Speed Sensor: Initial Inspection and Diagnostic Overview
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
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Vehicle Speed Sensor: Symptom Related Diagnostic Procedures
Chart #1 Speedometer And Cruise Control Inoperative; Code 24 Not Set
Symptom Table
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Locations
Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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Information and Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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MAF Sensor Circuit.
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Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
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Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
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Fuel Pump/Engine Oil Pressure Indicator Switch
Rear Of Engine
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Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
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Diagram Information and Instructions
Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Fuel Pump Switch/Engine Oil Pressure Gage Sensor
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Fuel Pump Relay Circuit
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Page 1090
Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
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Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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1095
Throttle Position Sensor: Locations
Component Location - Pictorial View
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1096
Component Location - Pictorial View
Throttle Body
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Information and Instructions
Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Information and Instructions > Page 1118
Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Throttle Position Sensor Circuit.
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Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
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Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
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Engine Harness/U/Hood Electrical Center, Right Side
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Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Page 1231
Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Page 1237
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Page 1238
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Page 1240
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Page 1242
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor Circuit
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Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
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Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
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Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
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Sensors and Arming Sensors <--> [Impact Sensor] > Component Information > Locations
LH Radiator Support
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Discriminating Sensors and Arming Sensors: Description and Operation
DESCRIPTION
The discriminating and arming sensors are used by the SIR system to determine whether or not
certain frontal crashes require deployment of the air bags.
OPERATION
The sensor consists of a sensing element, normally open switch contacts and a diagnostic resistor.
The sensing element closes the switch contacts when the vehicle velocity changes are severe
enough to warrant air bag deployment.
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Discriminating Sensors and Arming Sensors: Service and Repair
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
LEFT SENSOR
1. Disarm system as described in Air Bag System Disarming & Arming 2. Remove Connector
Position Assurance (CPA), then disconnect sensor electrical connector. 3. Remove sensor
mounting bolts, then the sensor. 4. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition key to the On position and verify the AIR BAG or SIR warning lamp flashes seven to
nine times, then turns off. If warning lamp
does not operate as specified, refer to Testing & Inspection.
RIGHT SENSOR
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Remove battery, then the
Connector Position Assurance (CPA). 3. Disconnect sensor electrical connector. 4. Remove sensor
mounting bolts, then the sensor. 5. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition key to the On position and verify the AIR BAG or SIR warning lamp flashes seven to
nine times, then turns off. If warning lamp
does not operate as specified, refer to System Diagnosis.
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Switch > Component Information > Locations > Component Locations
Underside Of Driver Seat, Passenger Seat Similar
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Seat Belt Buckle Switch: Connector Locations
Cross Car Harness
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Switch > Component Information > Locations > Component Locations > Page 1258
Cross Car Harness
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Sensor > Component Information > Technical Service Bulletins > Restraints - Passenger Presence System Information
Seat Occupant Sensor: Technical Service Bulletins Restraints - Passenger Presence System
Information
INFORMATION
Bulletin No.: 06-08-50-009F
Date: December 23, 2010
Subject: Information on Passenger Presence Sensing System (PPS or PSS) Concerns With
Custom Upholstery, Accessory Seat Heaters or Other Comfort Enhancing Devices
Models:
2011 and Prior GM Passenger Cars and Trucks Equipped with Passenger Presence Sensing
System
Supercede: This bulletin is being revised to update the model years. Please discard Corporate
Bulletin Number 06-08-50-009E (Section 08 - Body and Accessories).
Concerns About Safety and Alterations to the Front Passenger Seat
Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE THE
SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT AS RELEASED BY GM FOR THAT
VEHICLE. DO NOT ALTER THE SEAT COVERS OR SEAT-RELATED EQUIPMENT. ANY
ALTERATIONS TO SEAT COVERS OR GM ACCESSORIES DEFEATS THE INTENDED DESIGN
OF THE SYSTEM. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF
SUCH IMPROPER SEAT ALTERATIONS, INCLUDING ANY WARRANTY REPAIRS INCURRED.
The front passenger seat in many GM vehicles is equipped with a passenger sensing system that
will turn off the right front passenger's frontal airbag under certain conditions, such as when an
infant or child seat is present. In some vehicles, the passenger sensing system will also turn off the
right front passenger's seat mounted side impact airbag. For the system to function properly,
sensors are used in the seat to detect the presence of a properly-seated occupant. The passenger
sensing system may not operate properly if the original seat trim is replaced (1) by non-GM covers,
upholstery or trim, or (2) by GM covers, upholstery or trim designed for a different vehicle or (3) by
GM covers, upholstery or trim that has been altered by a trim shop, or (4) if any object, such as an
aftermarket seat heater or a comfort enhancing pad or device is installed under the seat fabric or
between the occupant and the seat fabric.
Aftermarket Seat Heaters, Custom Upholstery, and Comfort Enhancing Pads or Devices
Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE ONLY
SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT RELEASED AS GM
ACCESSORIES FOR THAT VEHICLE. DO NOT USE ANY OTHER TYPE OF SEAT COVERS OR
SEAT-RELATED EQUIPMENT, OR GM ACCESSORIES RELEASED FOR OTHER VEHICLE
APPLICATIONS. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF SUCH
IMPROPER SEAT ACCESSORIES, INCLUDING ANY WARRANTY REPAIRS MADE
NECESSARY BY SUCH USE.
Many types of aftermarket accessories are available to customers, upfitting shops, and dealers.
Some of these devices sit on top of, or are Velcro(R) strapped to the seat while others such as seat
heaters are installed under the seat fabric. Additionally, seat covers made of leather or other
materials may have different padding thickness installed that could prevent the Passenger Sensing
System from functioning properly. Never alter the vehicle seats. Never add pads or other devices to
the seat cushion, as this may interfere with the operation of the Passenger Sensing System and
either prevent proper deployment of the passenger airbag or prevent proper suppression of the
passenger air bag.
Disclaimer
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Switch > Component Information > Diagrams > Diagram Information and Instructions
Neutral Safety Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1268
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1269
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1270
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1272
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1273
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1274
Neutral Safety Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1275
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 1279
1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Neutral Safety Switch: Service and Repair
Fig. 4 Mechanical Neutral Safety System. Tilt Column
Fig. 5 Mechanical Neutral Safety System. Standard Column
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Fig. 6 Mechanical Neutral Safety System In Park Position
MECHANICAL
Actuation of the ignition switch is prevented by a mechanical lockout system Fig. 4 AND 5,. which
prevents the lock cylinder from rotating when the selector lever is out of Park or Neutral. When the
selector lever is in Park or Neutral, the slots in the bowl plate and the finger on the actuator rod
align, allowing the finger to pass through the bowl plate in turn actuating the ignition switch, Fig. 6.
If the selector lever is in any position other than Park or Neutral, the finger contacts the bowl plate
when the lock cylinder is rotated, thereby preventing full travel of the lock cylinder.
ELECTRIC
On models incorporating an electric neutral start switch, the start switch, back-up light switch and
parking brake vacuum release valve are combined into one unit. This unit is mounted on the
steering column under the instrument panel.
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Left Front Of Engine
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Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Power Steering Pressure Switch Circuit.
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Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
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Center Of Rear Crossmember
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Ride Height Sensor: Description and Operation
DESCRIPTION
The height sensor controls two circuits, compressor relay coil ground circuit and exhaust solenoid
coil ground circuit. To prevent energizing the compressor relay and exhaust solenoid circuits during
normal ride motions, the sensor circuit provides a predetermined delay before the ground circuit is
completed. The sensor electronically limits compressor run time and exhaust solenoid energized
time. This limit function is necessary to prevent continuous compressor operation in case of a
system leak or continuous exhaust solenoid operation. This timer is reset whenever the ignition is
turned Off and On, or height sensor exhaust or compressor signal changes. The height sensor is
mounted to the body frame in the rear of the vehicle. The sensor actuator arm is attached to the
control arm by a short link
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Ride Height Sensor: Testing and Inspection
CAUTION: When diagnostic procedures require that vehicle be raised on a hoist, it is important that
the rear axle assembly remains in the normal trim height position at all times. When a frame
contact hoist is used, two additional jack stands should be used to support the rear axle or control
arms in the normal trim height position.
1. Turn ignition Off, then On. This will reset height sensor timer circuits.
2. Raise vehicle on hoist. Ensure rear wheels or axle housing are supported and that vehicle is at
proper trim height.
3. Disconnect link from height sensor arm, then ensure sensor wiring and harness ground are
connected properly.
4. Move sensor arm upward. There should be a delay of 8-15 seconds before compressor turns on
and shocks start to inflate. As soon as shocks start to fill, stop compressor by moving sensor arm
down.
5. Move sensor arm down below position where compressor stopped. There should be a delay of
8-15 seconds before shocks start to deflate and vehicle lowers.
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Ride Height Sensor: Adjustments
ADJUSTMENTS
The link should be properly attached to the sensor arm and track bar, when making this
adjustment.
1. Loosen lock bolt securing metal arm to height sensor plastic arm. 2. To raise vehicle trim height,
move plastic arm upward and tighten lock bolt. 3. To lower vehicle trim height, loosen lock bolt
securing metal arm to height sensor plastic arm, then move plastic arm down. 4. If adjustment
cannot be made, check for correct sensor.
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Ride Height Sensor: Service and Repair
WARNING: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
1. Disconnect battery ground cable.
2. Raise and support vehicle.
3. Disconnect harness from sensor electrical connector by squeezing oval sides of the connector
lock to release locking tabs.
4. Remove link from height sensor arm, then remove sensor mounting screws or nuts and the
sensor.
5. Remove sensor mounting bracket to underbody attaching screws and remove bracket.
6. Reverse procedure to install, noting the following:
a. When connecting harness to sensor electrical connector, push connector into sensor plug until
sloped shoulder on rear edge of boss is visible
in plug slot. Push oval connector lock onto plug until its two locking tabs snap over shoulder of
sensor plug.
b. Perform height sensor operational check and adjustment procedure as described under Testing
and Inspection. See: Testing and Inspection
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Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
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Locations > Page 1355
RH Side Of Steering Column
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Locations > Page 1356
RH Side Of Steering Column
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Information and Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Transmission Temperature Sensor/Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Temperature Sensor/Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Information and Instructions > Page 1422
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Transmission and Drivetrain > Sensors
and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 1423
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Transmission and Drivetrain > Sensors
and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 1424
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Transmission and Drivetrain > Sensors
and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 1425
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Transmission and Drivetrain > Sensors
and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 1426
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Transmission and Drivetrain > Sensors
and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 1427
Transmission Range Switch Assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Transmission and Drivetrain > Sensors
and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Page 1428
Transmission Temperature Sensor/Switch: Description and Operation
The Transmission Fluid Temperature (TFT) sensor is a thermistor (a device that changes
resistance according to changes in temperature) used to indicate transmission fluid temperature.
High sensor resistance produces high signal input voltage which corresponds to low fluid
temperature. Low sensor resistance produces low signal input voltage which corresponds to high
fluid temperature. The Powertrain Control Module (PCM) uses the TFT sensor signal input to
determine the following:
^ Torque Converter Clutch (TCC) apply and release schedules.
^ Hot mode determination.
^ Shift quality.
The TFT sensor is part of the transmission range fluid pressure switch assembly and is attached to
the control valve body within the transmission. A fault in the Transmission Fluid Temperature (TFT)
sensor circuit will set a DTC 58. 59 or 79.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Heated Glass
Element Switch > Component Information > Diagrams
Rear Defogger Control Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Component Locations
Power Window Switch: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Component Locations > Page 1437
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Component Locations > Page 1438
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Component Locations > Page 1439
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Component Locations > Page 1440
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Component Locations > Page 1441
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Windows and Glass > Power Window
Switch > Component Information > Locations > Page 1442
Power Window Switch: Diagrams
Master Power Window Switch Assembly C1 and C2
Power Window Switch LH And RH Rear RH Front
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Washer
Fluid Level Switch > Component Information > Locations
LH Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Windshield
Washer Switch > Component Information > Locations > Component Locations
Windshield Washer Switch: Component Locations
Upper LH Side Of Steering Column
LH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Windshield
Washer Switch > Component Information > Locations > Component Locations > Page 1451
Windshield Washer Switch: Connector Locations
Lower LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Windshield
Washer Switch > Component Information > Locations > Component Locations > Page 1452
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Windshield
Washer Switch > Component Information > Locations > Page 1453
C216: Windshield Wiper/Washer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Component Locations
Wiper Switch: Component Locations
Upper LH Side Of Steering Column
LH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Component Locations > Page 1458
Wiper Switch: Connector Locations
Lower LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Component Locations > Page 1459
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Page 1460
C216: Windshield Wiper/Washer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Page 1461
Wiper Switch: Service and Repair
Fig. 18 Windshield Wiper Switch. Standard Steering Column
Fig. 19 Windshield Wiper Switch. Tilt Steering Column
Fig. 20 Windshield Wiper Switch Actuator Pivot Pin Replacement
1. Disconnect battery ground cable and remove turn signal switch as outlined under Turn Signal
Switch, Service and Repair. See: Sensors and
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Sensors and Switches > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Page 1462
Switches - Lighting and Horns/Turn Signal Switch/Service and Repair
2. Remove ignition lock, ignition switch and dimmer switch as outlined under Ignition Lock, Ignition
Switch and Dimmer Switch Service and
Repair. See: Steering and Suspension/Steering/Steering Column/Service and Repair
3. Remove ignition lock housing retaining screws and housing, Fig.18 and 19.. 4. Remove pivot
bolt and wiper switch from lock housing, Fig. 20. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > Customer
Interest: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening
Alignment: Customer Interest Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Important:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > Customer
Interest: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening > Page 1472
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > Customer
Interest: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening > Page 1473
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All
Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications
Alignment: All Technical Service Bulletins Steering/Suspension - Wheel Alignment Specifications
WARRANTY ADMINISTRATION
Bulletin No.: 05-03-07-009C
Date: December 09, 2010
Subject: Wheel Alignment Specifications, Requirements and Recommendations for GM Vehicles
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks
Supercede: This bulletin is being extensively revised to provide technicians and warranty
administrators with an all inclusive guide for wheel alignments. PLEASE FAMILIARIZE YOURSELF
WITH THESE UPDATES BEFORE PERFORMING YOUR NEXT GM WHEEL ALIGNMENT
SERVICE. Please discard Corporate Bulletin Number 05-03-07-009B (Section 03 - Suspension).
Purpose
The purpose of this bulletin is to provide retail, wholesale and fleet personnel with General Motors'
warranty service requirements and recommendations for customer concerns related to wheel
alignment. For your convenience, this bulletin updates and centralizes all of GM's Standard Wheel
Alignment Service Procedures, Policy Guidelines and bulletins on wheel alignment warranty
service.
Important PLEASE FAMILIARIZE YOURSELF WITH THESE UPDATES BEFORE PERFORMING
YOUR NEXT GM WHEEL ALIGNMENT SERVICE.
The following five (5) key steps are a summary of this bulletin and are REQUIRED in completing a
successful wheel alignment service.
1. Verify the vehicle is in an Original Equipment condition for curb weight, tires, wheels, suspension
and steering configurations. Vehicles
modified in any of these areas are not covered for wheel alignment warranty.
2. Review the customer concern relative to "Normal Operation" definitions. 3. Verify that vehicle is
within the "Mileage Policy" range. 4. Document wheel alignment warranty claims appropriately for
labor operations E2000 and E2020.
The following information must be documented or attached to the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
5. Use the proper wheel alignment equipment (preferred with print-out capability), process and the
appropriate calibration maintenance schedules.
Important If it is determined that a wheel alignment is necessary under warranty, use the proper
labor code for the repair. E2000 for Steering Wheel Angle and/or Front Toe set or E2020 for Wheel
Alignment Check/Adjust includes Caster, Camber and Toe set (Wheel alignment labor time for
other component repairs is to be charged to the component that causes a wheel alignment
operation.).
The following flowchart is to help summarize the information detailed in this bulletin and should be
used whenever a wheel alignment is performed.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All
Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 1479
Verify Original Equipment Condition of the Vehicle
- Verify that Original Equipment Tires and Wheels or Official GM Accessory Tires and Wheels are
on the vehicle.
- Verify that aftermarket suspension "Lift" or "Lowering" Kits or other suspension alterations have
NOT been done to the vehicle.
- Check for accidental damage to the vehicle; for example, severe pothole or curb impacts, collision
damage that may have affected the wheel alignment of the vehicle; e.g., engine cradles,
suspension control arms, axles, wheels, wheel covers, tires may show evidence of damage/impact.
- Check to be sure vehicle has seen "Normal Use" rather than abuse; e.g., very aggressive driving
may show up by looking at the tires and condition of the vehicle.
- Check for other additional equipment items that may significantly affect vehicle mass such as
large tool boxes, campers, snow plow packages (without the snowplow RPO), etc., especially in
trucks and cutaway/incomplete vehicles. Significant additional mass can affect trim height and
wheel alignment of the vehicle and may necessitate a customer pay wheel alignment when placed
semi-permanently in the vehicle (Upfitter instructions are to realign the vehicle after placement of
these types of items. (This typically applies to trucks and incomplete vehicles that can be upfit with
equipment such as the above.)
Customer Concerns, "Normal Operation" Conditions and "Mileage Policy"
Possible Concerns
The following are typical conditions that may require wheel alignment warranty service:
1. Lead/Pull: defined as "at a constant highway speed on a typical straight road, the amount of
effort required at the steering wheel to maintain the
vehicle's straight heading."
Important Please evaluate for the condition with hands-on the steering wheel. Follow the "Vehicle
Leads/Pulls" diagnostic tree located in SI to determine the cause of a lead/pull concern. Lead/Pull
concerns can be due to road crown or road slope, tires, wheel alignment or even in rare
circumstances a steering gear issue. Lead/pull concerns due to road crown are considered
"Normal Operation" and are NOT a warrantable condition -- the customer should be advised that
this is "Normal Operation."
Important Some customers may comment on a "Lead/Pull" when they hold the steering wheel in a
level condition. If so, this is more likely a "steering wheel angle" concern because the customer is
"steering" the vehicle to obtain a "level" steering wheel.
2. Steering wheel angle to the left or right (counter-clockwise or clockwise, respectively): Defined
as the steering wheel angle (clocking)
deviation from "level" while maintaining a straight heading on a typical straight road.
3. Irregular or Premature tire wear: Slight to very slight "feathering" or "edge" wear on the
shoulders of tires is NOT considered unusual and
should even out with a tire rotation; if the customer is concerned about a "feathering" condition of
the tires, the customer could be advised to rotate the tires earlier than the next scheduled
mileage/maintenance interval (but no later than the next interval). Be sure to understand the
customer's driving habits as this will also heavily influence the tire wear performance; tire wear from
aggressive or abusive driving habits is NOT a warrantable condition.
Important Slight or mild feathering, cupping, edge or heel/toe wear of tire tread shoulders is
"normal" and can show up very early in a tire/vehicle service mileage; in fact, some new tires can
show evidence of feathering from the factory. These issues do NOT affect the overall performance
and tread life of the tire. Dealer personnel should always check the customer's maintenance
records to ensure that tire inflation pressure is being maintained to placard and that the tires are
being rotated (modified-X pattern) at the proper mileage intervals. Wheel alignments are NOT to be
performed for the types of "Normal" Tire Feathering shown in Figures 1-4 below.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All
Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 1480
Figure 1: Full Tread View - "NORMAL" Tire "Feathering" Wear on the Shoulder/Adjacent/Center
Ribs
Figure 2: Tire Shoulder View Example 1 - "NORMAL" Tire "Feathering" Wear on the Shoulder
Figure 3: Tire Shoulder View Example 2 - "NORMAL" Tire "Feathering" Wear
Figure 4: Detail Side View of Tire Shoulder Area - "NORMAL" Tire "Feathering" Wear
Important When a wheel alignment is deemed necessary for tire wear, be sure to document on the
repair order, in as much detail as possible, the severity and type of tire wear (e.g., severe center
wear or severe inside or outside shoulder wear) and the position of the tire on the vehicle (RF, LF,
LR, RR). Please note the customer's concern with the wear such as, noise, appearance, wear life,
etc. A field product report with pictures of the tire wear condition is recommended. Refer to
Corporate Bulletin Number 02-00-89-002J and #07-00-89-036C.
4. Other repairs that affect wheel alignment; e.g., certain component replacement such as
suspension control arm replacement, engine cradle
adjustment/replace, steering gear replacement, steering tie rod replace, suspension strut/shock,
steering knuckle, etc. may require a wheel alignment.
Important If other components or repairs are identified as affecting the wheel alignment, policy calls
for the wheel alignment labor time to be charged to the replaced/repaired component's labor
operation time rather than the wheel alignment labor operations.
Important Vibration type customer concerns are generally NOT due to wheel alignment except in
the rare cases; e.g., extreme diagonal wear across the tread. In general, wheel alignments are
NOT to be performed as an investigation/correction for vibration concerns.
"Normal Operation" Conditions
Vehicle Lead/Pull Due to Road Crown or Slope:
As part of "Normal Operation," vehicles will follow side-to-side or left to right road crown or slope.
Be sure to verify from the customer the types of roads they are driving as they may not recognize
the influence of road crown on vehicle lead/pull and steering wheel angle. If a vehicle requires
significant steering effort to prevent it from "climbing" the road crown there may be an issue to be
looked into further.
Important
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All
Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 1481
A wheel alignment will generally NOT correct vehicles that follow the road crown since this is within
"Normal Operation."
Mileage Policy
The following mileage policy applies for E2020 and E2000 labor operations: Note
Wheel Alignment is NOT covered under the New Vehicle Limited Warranty for Express and Savana
Cutaway vehicles as these vehicles require Upfitters to set the wheel alignment after completing
the vehicles.
- 0-800 km (0-500 mi): E2000/E2020 claims ONLY allowed with Call Center Authorization. Due to
the tie down during shipping, the vehicle's suspension requires some time to reach normal
operating position. For this reason, new vehicles are generally NOT to be aligned until they have
accumulated at least 800 km (500 mi). A field product report should accompany any claim within
this mileage range.
- 801-12,000 km (501-7,500 mi):
- If a vehicle came from the factory with incorrect alignment settings, any resulting off-angle
steering wheel, lead/pull characteristics or the rare occurrence of excessive tire wear would be
apparent early in the life of the vehicle. The following policy applies:
- Vehicles 100% Factory Set/Measured for Caster/Camber/Toe - Escalade/ESV/EXT,
Tahoe/Suburban, Yukon/XL/Denali, Silverado/Sierra, Express/Savana, Corvette and
Colorado/Canyon: E2000/E2020 Claims: Call Center Authorization Required
- All Vehicles NOT 100% Factory Set/Measured for Caster/Camber/Toe as noted above:
E2000/E2020 Claims: Dealer Service Manager Authorization Required
- 12,001 km and beyond (7,501 miles and beyond): During this period, customers are responsible
for the wheel alignment expense or dealers may provide on a case-by case basis a one-time
customer enthusiasm claim up to 16,000 km (10,000 mi). In the event that a defective component
required the use of the subject labor operations, the identified defective component labor operation
will include the appropriate labor time for a wheel alignment as an add condition to the component
repair.
Important Only one wheel alignment labor operation claim (E2000 or E2020) may be used per VIN.
Warranty Documentation Requirements
When a wheel alignment service has been deemed necessary, the following items will need to be
clearly documented on/with the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
1. Document the customer concern in as much detail as possible on the repair order and in the
warranty administration system. Preferred examples:
- Steering wheel is off angle in the counterclockwise direction by approximately x degrees or
clocking position.
- Vehicle lead/pulls to the right at approximately x-y mph. Vehicle will climb the road crown. Severe,
Moderate or Slight.
- RF and LF tires are wearing on the outside shoulders with severe feathering.
Important In the event of a lead/pull or steering wheel angle concern, please note the direction of
lead/pull (left or right) or direction of steering wheel angle (clockwise or counterclockwise) on the
repair order and within the warranty claim verbatim.
Important In the event of a tire wear concern, please note the position on the vehicle and where the
wear is occurring on the tire; i.e., the RF tire is wearing on the inside shoulder.
2. Document the technician's findings on cause and correction of the issue. Examples:
- Reset LF toe from 0.45 degrees to 0.10 degrees and RF toe from -0.25 degrees to 0.10 degrees
to correct the steering wheel angle from 5 degrees counterclockwise to 0 degrees.
- Reset LF camber from 0.25 degrees to -0.05 degrees to correct the cross-camber condition of
+0.30 degrees to 0.00 degrees on the vehicle.
- Front Sum toe was found to be 0.50 degrees, reset to 0.20 degrees.
3. Print-out the "Before" and "After" wheel alignment measurements/settings and attach them to the
Repair Order or if print-out capability is not
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Specifications > Page 1482
available, measurements may also be clearly and legibly handwritten into the Wheel Alignment
Repair Order Questionnaire attached to this bulletin.
4. Attach the Wheel Alignment Repair Order Questionnaire below along with the print-out of
"Before" and "After" wheel alignment measurements to
the Repair Order and retain for use by GM.
Wheel Alignment Equipment and Process
Wheel alignments must be performed with a quality machine that will give accurate results when
performing checks. "External Reference" (image-based camera technology) is preferred. Please
refer to Corporate Bulletin Number 05-00-89-029B: General Motors Dealership Critical Equipment
Requirements and Recommendations.
Requirements:
- Computerized four wheel alignment system.
- Computer capable of printing before and after alignment reports.
- Computer capable of time and date stamp printout.
- Racking system must have jacking capability
- Racking system must be capable of level to 1.6 mm (1/16 in)
- Appropriate wheel stops and safety certification
- Built-in turn plates and slip plates
- Wheel clamps capable of attaching to 20" or larger wheels
- Racking capable of accepting any GM passenger car or light duty truck
- Operator properly trained and ASE-certified (U.S. only) in wheel alignment
Recommendations:
Racking should have front and rear jacking capability.
Equipment Maintenance and Calibration:
Alignment machines must be regularly calibrated in order to give correct information. Most
manufacturers recommend the following:
- Alignment machines with "internal reference" sensors should be checked (and calibrated, if
necessary) every six months.
- Alignment machines with "external reference" (image-based camera technology) should be
checked (and calibrated, if necessary) once a year.
- Racks must be kept level to within 1.6 mm (1/16 in).
- If any instrument that is part of the alignment machine is dropped or damaged in some way,
check the calibration immediately.
Check with the manufacturer of your specific equipment for their recommended service/calibration
schedule.
Wheel Alignment Process
When performing wheel alignment measurement and/or adjustment, the following steps should be
taken:
Preliminary Steps:
1. Verify that the vehicle has a full tank of fuel (compensate as necessary). 2. Inspect the wheels
and the tires for damage. 3. Inspect the tires for the proper inflation and irregular tire wear. 4.
Inspect the wheel bearings for excessive play. 5. Inspect all suspension and steering parts for
looseness, wear, or damage. 6. Inspect the steering wheel for excessive drag or poor return due to
stiff or rusted linkage or suspension components. 7. Inspect the vehicle trim height. 8. Compensate
for frame angle on targeted vehicles (refer to Wheel Alignment Specifications in SI).
Satisfactory vehicle operation may occur over a wide range of alignment angles. However, if the
wheel alignment angles are not within the range of specifications, adjust the wheel alignment to the
specifications. Refer to Wheel Alignment Specifications in SI. Give consideration to excess loads,
such as tool boxes, sample cases, etc. Follow the wheel alignment equipment manufacturer's
instructions.
Measure/Adjust:
Important Prior to making any adjustments to wheel alignment on a vehicle, technicians must verify
that the wheel alignment specifications loaded into their wheel alignment machine are up-to-date
by comparing these to the wheel alignment specifications for the appropriate model and model year
in SI. Using incorrect and/or outdated specifications may result in unnecessary adjustments,
irregular and/or premature tire wear and repeat customer concerns
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Important When performing adjustments to vehicles requiring a 4-wheel alignment, set the rear
wheel alignment angles first in order to obtain proper front wheel alignment angles.
Perform the following steps in order to measure the front and rear alignment angles:
1. Install the alignment equipment according to the manufacturer's instructions. 2. Jounce the front
and the rear bumpers 3 times prior to checking the wheel alignment. 3. Measure the alignment
angles and record the readings.
If necessary, adjust the wheel alignment to vehicle specification and record the before and after
measurements. Refer to Wheel Alignment Specifications in SI.
Important Technicians must refer to SI for the correct wheel alignment specifications. SI is the only
source of GM wheel alignment specifications that is kept up-to-date throughout the year.
Test drive vehicle to ensure proper repair.
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Specifications > Page 1484
Frame Angle Measurement (Express / Savana Only) ........
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Specifications > Page 1485
What corrected the customer concern and was the repair verified?
Please Explain: .............
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All
Technical Service Bulletins for Alignment: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening
Alignment: All Technical Service Bulletins Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Important:
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Page 1490
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
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Page 1491
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
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Alignment: All Technical Service Bulletins Steering/Suspension - Wheel Alignment Specifications
WARRANTY ADMINISTRATION
Bulletin No.: 05-03-07-009C
Date: December 09, 2010
Subject: Wheel Alignment Specifications, Requirements and Recommendations for GM Vehicles
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks
Supercede: This bulletin is being extensively revised to provide technicians and warranty
administrators with an all inclusive guide for wheel alignments. PLEASE FAMILIARIZE YOURSELF
WITH THESE UPDATES BEFORE PERFORMING YOUR NEXT GM WHEEL ALIGNMENT
SERVICE. Please discard Corporate Bulletin Number 05-03-07-009B (Section 03 - Suspension).
Purpose
The purpose of this bulletin is to provide retail, wholesale and fleet personnel with General Motors'
warranty service requirements and recommendations for customer concerns related to wheel
alignment. For your convenience, this bulletin updates and centralizes all of GM's Standard Wheel
Alignment Service Procedures, Policy Guidelines and bulletins on wheel alignment warranty
service.
Important PLEASE FAMILIARIZE YOURSELF WITH THESE UPDATES BEFORE PERFORMING
YOUR NEXT GM WHEEL ALIGNMENT SERVICE.
The following five (5) key steps are a summary of this bulletin and are REQUIRED in completing a
successful wheel alignment service.
1. Verify the vehicle is in an Original Equipment condition for curb weight, tires, wheels, suspension
and steering configurations. Vehicles
modified in any of these areas are not covered for wheel alignment warranty.
2. Review the customer concern relative to "Normal Operation" definitions. 3. Verify that vehicle is
within the "Mileage Policy" range. 4. Document wheel alignment warranty claims appropriately for
labor operations E2000 and E2020.
The following information must be documented or attached to the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
5. Use the proper wheel alignment equipment (preferred with print-out capability), process and the
appropriate calibration maintenance schedules.
Important If it is determined that a wheel alignment is necessary under warranty, use the proper
labor code for the repair. E2000 for Steering Wheel Angle and/or Front Toe set or E2020 for Wheel
Alignment Check/Adjust includes Caster, Camber and Toe set (Wheel alignment labor time for
other component repairs is to be charged to the component that causes a wheel alignment
operation.).
The following flowchart is to help summarize the information detailed in this bulletin and should be
used whenever a wheel alignment is performed.
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Page 1497
Verify Original Equipment Condition of the Vehicle
- Verify that Original Equipment Tires and Wheels or Official GM Accessory Tires and Wheels are
on the vehicle.
- Verify that aftermarket suspension "Lift" or "Lowering" Kits or other suspension alterations have
NOT been done to the vehicle.
- Check for accidental damage to the vehicle; for example, severe pothole or curb impacts, collision
damage that may have affected the wheel alignment of the vehicle; e.g., engine cradles,
suspension control arms, axles, wheels, wheel covers, tires may show evidence of damage/impact.
- Check to be sure vehicle has seen "Normal Use" rather than abuse; e.g., very aggressive driving
may show up by looking at the tires and condition of the vehicle.
- Check for other additional equipment items that may significantly affect vehicle mass such as
large tool boxes, campers, snow plow packages (without the snowplow RPO), etc., especially in
trucks and cutaway/incomplete vehicles. Significant additional mass can affect trim height and
wheel alignment of the vehicle and may necessitate a customer pay wheel alignment when placed
semi-permanently in the vehicle (Upfitter instructions are to realign the vehicle after placement of
these types of items. (This typically applies to trucks and incomplete vehicles that can be upfit with
equipment such as the above.)
Customer Concerns, "Normal Operation" Conditions and "Mileage Policy"
Possible Concerns
The following are typical conditions that may require wheel alignment warranty service:
1. Lead/Pull: defined as "at a constant highway speed on a typical straight road, the amount of
effort required at the steering wheel to maintain the
vehicle's straight heading."
Important Please evaluate for the condition with hands-on the steering wheel. Follow the "Vehicle
Leads/Pulls" diagnostic tree located in SI to determine the cause of a lead/pull concern. Lead/Pull
concerns can be due to road crown or road slope, tires, wheel alignment or even in rare
circumstances a steering gear issue. Lead/pull concerns due to road crown are considered
"Normal Operation" and are NOT a warrantable condition -- the customer should be advised that
this is "Normal Operation."
Important Some customers may comment on a "Lead/Pull" when they hold the steering wheel in a
level condition. If so, this is more likely a "steering wheel angle" concern because the customer is
"steering" the vehicle to obtain a "level" steering wheel.
2. Steering wheel angle to the left or right (counter-clockwise or clockwise, respectively): Defined
as the steering wheel angle (clocking)
deviation from "level" while maintaining a straight heading on a typical straight road.
3. Irregular or Premature tire wear: Slight to very slight "feathering" or "edge" wear on the
shoulders of tires is NOT considered unusual and
should even out with a tire rotation; if the customer is concerned about a "feathering" condition of
the tires, the customer could be advised to rotate the tires earlier than the next scheduled
mileage/maintenance interval (but no later than the next interval). Be sure to understand the
customer's driving habits as this will also heavily influence the tire wear performance; tire wear from
aggressive or abusive driving habits is NOT a warrantable condition.
Important Slight or mild feathering, cupping, edge or heel/toe wear of tire tread shoulders is
"normal" and can show up very early in a tire/vehicle service mileage; in fact, some new tires can
show evidence of feathering from the factory. These issues do NOT affect the overall performance
and tread life of the tire. Dealer personnel should always check the customer's maintenance
records to ensure that tire inflation pressure is being maintained to placard and that the tires are
being rotated (modified-X pattern) at the proper mileage intervals. Wheel alignments are NOT to be
performed for the types of "Normal" Tire Feathering shown in Figures 1-4 below.
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Page 1498
Figure 1: Full Tread View - "NORMAL" Tire "Feathering" Wear on the Shoulder/Adjacent/Center
Ribs
Figure 2: Tire Shoulder View Example 1 - "NORMAL" Tire "Feathering" Wear on the Shoulder
Figure 3: Tire Shoulder View Example 2 - "NORMAL" Tire "Feathering" Wear
Figure 4: Detail Side View of Tire Shoulder Area - "NORMAL" Tire "Feathering" Wear
Important When a wheel alignment is deemed necessary for tire wear, be sure to document on the
repair order, in as much detail as possible, the severity and type of tire wear (e.g., severe center
wear or severe inside or outside shoulder wear) and the position of the tire on the vehicle (RF, LF,
LR, RR). Please note the customer's concern with the wear such as, noise, appearance, wear life,
etc. A field product report with pictures of the tire wear condition is recommended. Refer to
Corporate Bulletin Number 02-00-89-002J and #07-00-89-036C.
4. Other repairs that affect wheel alignment; e.g., certain component replacement such as
suspension control arm replacement, engine cradle
adjustment/replace, steering gear replacement, steering tie rod replace, suspension strut/shock,
steering knuckle, etc. may require a wheel alignment.
Important If other components or repairs are identified as affecting the wheel alignment, policy calls
for the wheel alignment labor time to be charged to the replaced/repaired component's labor
operation time rather than the wheel alignment labor operations.
Important Vibration type customer concerns are generally NOT due to wheel alignment except in
the rare cases; e.g., extreme diagonal wear across the tread. In general, wheel alignments are
NOT to be performed as an investigation/correction for vibration concerns.
"Normal Operation" Conditions
Vehicle Lead/Pull Due to Road Crown or Slope:
As part of "Normal Operation," vehicles will follow side-to-side or left to right road crown or slope.
Be sure to verify from the customer the types of roads they are driving as they may not recognize
the influence of road crown on vehicle lead/pull and steering wheel angle. If a vehicle requires
significant steering effort to prevent it from "climbing" the road crown there may be an issue to be
looked into further.
Important
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Page 1499
A wheel alignment will generally NOT correct vehicles that follow the road crown since this is within
"Normal Operation."
Mileage Policy
The following mileage policy applies for E2020 and E2000 labor operations: Note
Wheel Alignment is NOT covered under the New Vehicle Limited Warranty for Express and Savana
Cutaway vehicles as these vehicles require Upfitters to set the wheel alignment after completing
the vehicles.
- 0-800 km (0-500 mi): E2000/E2020 claims ONLY allowed with Call Center Authorization. Due to
the tie down during shipping, the vehicle's suspension requires some time to reach normal
operating position. For this reason, new vehicles are generally NOT to be aligned until they have
accumulated at least 800 km (500 mi). A field product report should accompany any claim within
this mileage range.
- 801-12,000 km (501-7,500 mi):
- If a vehicle came from the factory with incorrect alignment settings, any resulting off-angle
steering wheel, lead/pull characteristics or the rare occurrence of excessive tire wear would be
apparent early in the life of the vehicle. The following policy applies:
- Vehicles 100% Factory Set/Measured for Caster/Camber/Toe - Escalade/ESV/EXT,
Tahoe/Suburban, Yukon/XL/Denali, Silverado/Sierra, Express/Savana, Corvette and
Colorado/Canyon: E2000/E2020 Claims: Call Center Authorization Required
- All Vehicles NOT 100% Factory Set/Measured for Caster/Camber/Toe as noted above:
E2000/E2020 Claims: Dealer Service Manager Authorization Required
- 12,001 km and beyond (7,501 miles and beyond): During this period, customers are responsible
for the wheel alignment expense or dealers may provide on a case-by case basis a one-time
customer enthusiasm claim up to 16,000 km (10,000 mi). In the event that a defective component
required the use of the subject labor operations, the identified defective component labor operation
will include the appropriate labor time for a wheel alignment as an add condition to the component
repair.
Important Only one wheel alignment labor operation claim (E2000 or E2020) may be used per VIN.
Warranty Documentation Requirements
When a wheel alignment service has been deemed necessary, the following items will need to be
clearly documented on/with the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
1. Document the customer concern in as much detail as possible on the repair order and in the
warranty administration system. Preferred examples:
- Steering wheel is off angle in the counterclockwise direction by approximately x degrees or
clocking position.
- Vehicle lead/pulls to the right at approximately x-y mph. Vehicle will climb the road crown. Severe,
Moderate or Slight.
- RF and LF tires are wearing on the outside shoulders with severe feathering.
Important In the event of a lead/pull or steering wheel angle concern, please note the direction of
lead/pull (left or right) or direction of steering wheel angle (clockwise or counterclockwise) on the
repair order and within the warranty claim verbatim.
Important In the event of a tire wear concern, please note the position on the vehicle and where the
wear is occurring on the tire; i.e., the RF tire is wearing on the inside shoulder.
2. Document the technician's findings on cause and correction of the issue. Examples:
- Reset LF toe from 0.45 degrees to 0.10 degrees and RF toe from -0.25 degrees to 0.10 degrees
to correct the steering wheel angle from 5 degrees counterclockwise to 0 degrees.
- Reset LF camber from 0.25 degrees to -0.05 degrees to correct the cross-camber condition of
+0.30 degrees to 0.00 degrees on the vehicle.
- Front Sum toe was found to be 0.50 degrees, reset to 0.20 degrees.
3. Print-out the "Before" and "After" wheel alignment measurements/settings and attach them to the
Repair Order or if print-out capability is not
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Page 1500
available, measurements may also be clearly and legibly handwritten into the Wheel Alignment
Repair Order Questionnaire attached to this bulletin.
4. Attach the Wheel Alignment Repair Order Questionnaire below along with the print-out of
"Before" and "After" wheel alignment measurements to
the Repair Order and retain for use by GM.
Wheel Alignment Equipment and Process
Wheel alignments must be performed with a quality machine that will give accurate results when
performing checks. "External Reference" (image-based camera technology) is preferred. Please
refer to Corporate Bulletin Number 05-00-89-029B: General Motors Dealership Critical Equipment
Requirements and Recommendations.
Requirements:
- Computerized four wheel alignment system.
- Computer capable of printing before and after alignment reports.
- Computer capable of time and date stamp printout.
- Racking system must have jacking capability
- Racking system must be capable of level to 1.6 mm (1/16 in)
- Appropriate wheel stops and safety certification
- Built-in turn plates and slip plates
- Wheel clamps capable of attaching to 20" or larger wheels
- Racking capable of accepting any GM passenger car or light duty truck
- Operator properly trained and ASE-certified (U.S. only) in wheel alignment
Recommendations:
Racking should have front and rear jacking capability.
Equipment Maintenance and Calibration:
Alignment machines must be regularly calibrated in order to give correct information. Most
manufacturers recommend the following:
- Alignment machines with "internal reference" sensors should be checked (and calibrated, if
necessary) every six months.
- Alignment machines with "external reference" (image-based camera technology) should be
checked (and calibrated, if necessary) once a year.
- Racks must be kept level to within 1.6 mm (1/16 in).
- If any instrument that is part of the alignment machine is dropped or damaged in some way,
check the calibration immediately.
Check with the manufacturer of your specific equipment for their recommended service/calibration
schedule.
Wheel Alignment Process
When performing wheel alignment measurement and/or adjustment, the following steps should be
taken:
Preliminary Steps:
1. Verify that the vehicle has a full tank of fuel (compensate as necessary). 2. Inspect the wheels
and the tires for damage. 3. Inspect the tires for the proper inflation and irregular tire wear. 4.
Inspect the wheel bearings for excessive play. 5. Inspect all suspension and steering parts for
looseness, wear, or damage. 6. Inspect the steering wheel for excessive drag or poor return due to
stiff or rusted linkage or suspension components. 7. Inspect the vehicle trim height. 8. Compensate
for frame angle on targeted vehicles (refer to Wheel Alignment Specifications in SI).
Satisfactory vehicle operation may occur over a wide range of alignment angles. However, if the
wheel alignment angles are not within the range of specifications, adjust the wheel alignment to the
specifications. Refer to Wheel Alignment Specifications in SI. Give consideration to excess loads,
such as tool boxes, sample cases, etc. Follow the wheel alignment equipment manufacturer's
instructions.
Measure/Adjust:
Important Prior to making any adjustments to wheel alignment on a vehicle, technicians must verify
that the wheel alignment specifications loaded into their wheel alignment machine are up-to-date
by comparing these to the wheel alignment specifications for the appropriate model and model year
in SI. Using incorrect and/or outdated specifications may result in unnecessary adjustments,
irregular and/or premature tire wear and repeat customer concerns
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Page 1501
Important When performing adjustments to vehicles requiring a 4-wheel alignment, set the rear
wheel alignment angles first in order to obtain proper front wheel alignment angles.
Perform the following steps in order to measure the front and rear alignment angles:
1. Install the alignment equipment according to the manufacturer's instructions. 2. Jounce the front
and the rear bumpers 3 times prior to checking the wheel alignment. 3. Measure the alignment
angles and record the readings.
If necessary, adjust the wheel alignment to vehicle specification and record the before and after
measurements. Refer to Wheel Alignment Specifications in SI.
Important Technicians must refer to SI for the correct wheel alignment specifications. SI is the only
source of GM wheel alignment specifications that is kept up-to-date throughout the year.
Test drive vehicle to ensure proper repair.
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Page 1502
Frame Angle Measurement (Express / Savana Only) ........
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Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment Specifications >
Page 1503
What corrected the customer concern and was the repair verified?
Please Explain: .............
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All Other
Service Bulletins for Alignment: > Page 1504
Alignment: By Symptom
Technical Service Bulletin # 533403 Date: 950501
Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
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Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All Other
Service Bulletins for Alignment: > Page 1505
Important:
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All Other
Service Bulletins for Alignment: > Page 1506
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All Other
Service Bulletins for Alignment: > Page 1507
Technical Service Bulletin # 533403 Date: 950501
Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All Other
Service Bulletins for Alignment: > Page 1508
Important:
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Technical Service Bulletins > All Other
Service Bulletins for Alignment: > Page 1509
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Specifications > Vehicle Ride (Trim)
Height Specifications
Alignment: Specifications Vehicle Ride (Trim) Height Specifications
Fig. 4 Vehicle Ride Height Measurement Locations & Specifications
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Specifications > Vehicle Ride (Trim)
Height Specifications > Page 1512
Alignment: Specifications Alignment Specifications
Front Alignment Specifications
Caster Angle, Degrees
Limits ...................................................................................................................................................
....................................................................... [01] Desired .................................................................
....................................................................................................................................................... [03]
Camber Angle, Degrees
Limits ...................................................................................................................................................
................................................................ - 1 to +1 Desired .................................................................
........................................................................................................................................................... 0
Total Toe, Degrees ..............................................................................................................................
............................................................... -.04 to +.36
Ball Joint Wear, Inch
Lower Ball Stud [02] ............................................................................................................................
..................................................................... .050 Upper Ball Stud [02] ..............................................
................................................................................................................................................... .125
[01] Left side, +2.25 to +4.25; right side, +2.75 to +4.75.
[02] Refer to Suspension/Ball Joint, lower or Upper/Service and Repair for proper ball joint
inspection procedure.
[03] Left side, +3.25; right side, +3.75.
Rear Alignment Specifications
Thrust Angle, Degrees .........................................................................................................................
.............................................................. -.15 to +.15
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Service and Repair > Preliminary
Inspection
Alignment: Service and Repair Preliminary Inspection
1. Inspect tires for proper inflation and similar tread wear. 2. Inspect hub and bearing for excessive
wear, repair as required. 3. Inspect ball joints. 4. Inspect tie rod ends for excessive looseness. 5.
Check wheel and tire runout. 6. Inspect vehicle ride height. 7. Inspect rack and pinion for looseness
at frame. 8. Ensure proper strut operation. 9. Check suspension and steering components for
damage, replace as required.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Service and Repair > Preliminary
Inspection > Page 1515
Alignment: Service and Repair Ride/Trim Height Measurement and Adjustment
Fig. 4 Vehicle Ride Height Measurement Locations & Specifications
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Service and Repair > Preliminary
Inspection > Page 1516
Alignment: Service and Repair Front Wheel Alignment
Front Caster Adjustment
Fig. 1 Caster & Camber Adjustments
Caster adjustments are made by means of shims between the upper control arm inner support
shaft and the support bracket attached to the frame, Fig. 1. Shims may be added, subtracted or
transferred to change the readings. Transfer shims from front to rear or rear to front. The transfer of
one shim to the front bolt from the rear bolt will decrease positive caster. One shim (1/32 inch)
transferred from the rear bolt to the front bolt will change caster about 1/2 degree.
Front Camber Adjustment
Fig. 1 Caster & Camber Adjustments
Camber adjustments are made by means of shims between the upper control arm inner support
shaft and the support bracket attached to the frame, Fig. 1. Shims may be added, subtracted or
transferred to change the readings. Change shims at both the front and rear of the shaft. Adding an
equal number of shims at both front and rear of the support shaft will decrease positive camber.
One shim (1/32 inch) at each location will move camber approximately 1/6 degree.
Front Toe Adjustment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Alignment > System Information > Service and Repair > Preliminary
Inspection > Page 1517
Fig. 2 Toe-in Adjustment
Toe-in can be adjusted by loosening the clamp bolts at each end of each tie rod and turning each
tie rod to increase or decrease its length as necessary until proper toe-in is secured and the
steering gear is on the high point for straight-ahead driving, Fig. 2.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Fuel Pressure > Diagnostic
Connector - Fuel Pump > Component Information > Locations
Diagnostic Connector - Fuel Pump: Locations
The fuel pump test connector is located in the engine compartment near the A/C accumulator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Fuel Pressure > Fuel Pressure
Test Port > Component Information > Locations
Fuel Pressure Test Port
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Fuel Pressure > Fuel Pressure
Test Port > Component Information > Locations > Page 1526
Fuel Pressure Test Port: Service and Repair
Fuel Test Port Valve
CLEAN
^ Area around fuel pressure connection with GM X-3OA or equivalent.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery System / Service and Repair.
3. Fuel pressure connection valve assembly.
INSTALL OR CONNECT
1. Fuel pressure connection valve assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten
seconds. Again turn to "ON" position, and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air/Fuel Mixture > System
Information > Specifications
Air/Fuel Mixture: Specifications
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air/Fuel Mixture > System
Information > Specifications > Page 1530
Air/Fuel Mixture: Adjustments
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Idle Speed > System
Information > Specifications
Idle Speed: Specifications
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Idle Speed > System
Information > Specifications > Page 1534
Idle Speed: Adjustments
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air
Cleaner Fresh Air Duct/Hose > Component Information > Locations
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Customer Interest for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Customer Interest for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 1547
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 1553
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Page 1554
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Page 1555
Air Filter Element: Service and Repair
Air Ducting
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Page 1556
REMOVE OR DISCONNECT
1. Loosen wing nuts at front of air cleaner housing. 2. Lift air cleaner lid, Mass Air Flow (MAF)
sensor and resonator as a unit. 3. Remove air filter element.
INSTALL OR CONNECT
1. Install air filter element. 2. Move air cleaner lid, MAF sensor and resonator into place. 3. Tighten
wing nuts. 4. Check clamps at MAF sensor and tighten if necessary. 5. Check joints between duct,
resonators and throttle body for possible air leaks. Repair if necessary.
NOTICE: If the Mass Air Flow (MAF) sensor is installed backwards, the system will go rich. An
arrow cast into the plastic portion of the sensor indicates proper air flow direction. The arrow must
point toward the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Fuel Filter > Fuel Pressure
Release > System Information > Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Firing Order > Component
Information > Specifications > Ignition Firing Order
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Ignition Timing > Number One
Cylinder > Component Information > Locations > Number 1 Cylinder Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Ignition Timing > Timing Marks
and Indicators > System Information > Locations > Crankshaft Rotation
Timing Marks and Indicators: Locations Crankshaft Rotation
Crankshaft Rotation (Typical Crankshaft Pulley)
Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the
generic image.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Ignition Timing > Timing Marks
and Indicators > System Information > Locations > Crankshaft Rotation > Page 1574
Timing Marks and Indicators: Locations Timing Marks
The ignition timing is completely controlled by the Powertrain Control Module (PCM). No timing
reference marks are provided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications
Spark Plug Wire: Specifications
Wire Harness Support Bolt / Screw
............................................................................................................................................................
40 Nm (30 lb ft.)
Wire Harness Support Channel Bolt / Screw (Right)
................................................................................................................................ 12 Nm (106 lb in.)
Wire Harness Support Channel Bolt/Screw (Left)
..................................................................................................................................... 12 Nm (106 lb
ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1578
Spark Plug Wire: Locations
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1579
Spark Plug Harness Routing
The spark plug wires run down both sides of the engine block under the exhaust manifolds.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1580
Spark Plug Wire: Description and Operation
The spark plug wire hamess assemblies use carbon impregnated cord conductors, encased in 8
mm (5 / 16-inch) diameter silicone jackets. The silicone jackets withstand very high temperatures
and also provide excellent insulation for the high voltage of the system. Silicone spark plug boots
form a tight seal to the spark plugs.
The material used to construct spark plug wires is very soft. This wire will withstand more heat and
carry a higher voltage, but chaffing and cutting become easier. The spark plug wires must be
routed correctly to prevent chafing or cutting. When removing a spark plug wire from a spark plug,
twist the boot on the spark plug one-half turn while pulling on the boot.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1581
Spark Plug Wire: Testing and Inspection
Inspect spark plug wires visually first for any cuts, burns, or damage. While engine is running,
inspect for any arcing to ground or other components. Use a spray bottle to lightly coat the spark
plug wires with water while observing idle quality. If idle quality diminishes or engine stalls, spark
plug wires should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1582
Spark Plug Wire: Service and Repair
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1583
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1584
Spark Plug Harness Routing
NOTICE: The boots should be twisted one-half turn while removing. Do not pull on the wire
harnesses to remove them from the spark plugs. Pull on the boots, or use a tool designed for this
purpose.
REMOVE OR DISCONNECT
Numbers included in this procedure refer to caption numbers in the included images.
1. Left bank spark plug wire boots from spark plugs. 2. Left bank spark plug wire harness support
channel bolts / screws (19) and channel. Rear bolt / screw (19) is located behind exhaust manifold
takedown. Loosen this bolt / screw using a 10 mm wrench then slide channel upward to disengage
from bolt / screw (19).
3. Left bank spark plug wire harness from clip (17) located behind air injection reactor (AIR) pump.
4. Right bank spark plug wire boots from spark plugs. 5. Air intake resonator.
With mechanical cooling fan: A. Upper radiator fan shroud, B. Loosen fan pulley nuts. C. Fan belt.
D. Mechanical fan and pulley. E. Mechanical fan pulley bracket nuts and bracket. F. Radiator outlet
pipe nuts from A/C compressor mounting studs.
6. Serpentine drive belt. 7. Raise and suitably support vehicle. 8. Transmission oil cooler line
support bolt / screw from accessory drive bracket. 9. Serpentine drive belt tensioner bolts/screws
and tensioner.
10. A/C compressor attaching bolts/screws
Reposition A/C compressor to provide access to front wire harness support (27).
11. Right wire harness support bolt / screw (28). 12. Right wire harness from support (27). 13. Left
and right bank spark plug wire harnesses (6) from distributor. 14. Left wire harness from clips (17,
20, 21 and 23).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug Wire <--> [Ignition
Cable] > Component Information > Specifications > Page 1585
^ Insert screwdriver into tab on top of clip to disengage.
15. Right wire harness from clips (16, 17, and 21).
^ Insert screwdriver into tab on top of clip to disengage.
NOTICE: When replacing spark plug wire harnesses (secondary wiring), route the wire harnesses
correctly and through the proper retainers. Failure to
route the wire harnesses properly can lead to radio ignition noise and cross-firing of the spark
plugs, or shorting of the leads to ground.
INSTALL OR CONNECT
1. Right wire harness to clips (16, 17 and 21). 2. Left wire harness to clips (17, 20, 21 and 23). 3.
Right wire harness to support (27). 4. Right wire harness support bolt / screw (28).
Tighten ^
Bolt / screw (28) to 40 Nm (30 lb ft.).
5. A/C compressor to bracket. 6. A/C compressor attaching bolts / screws and rear bracket nut.
Tighten A. A/C compressor bolts / screws to 50 Nm (37 lb ft.). B. A/C compressor rear bracket nut
to 41 Nm (30 lb ft.).
7. Serpentine drive belt tensioner and tensioner bolts / screws.
Tighten ^
Tensioner bolts / screws to 25 Nm (18 lb ft.).
8. Transmission oil cooler line support bolt / screw.
Tighten ^
Oil cooler line support bolt / screw to 1.9 Nm (17 lb in.).
9. Lower vehicle.
10. Serpentine drive belt.
With mechanical cooling fan: A. Radiator outlet pipe nuts from A/C compressor mounting studs.
Tighten ^
Radiator outlet pipe nuts to 16 Nm (12 lb ft.).
B. Mechanical fan pulley bracket nuts and bracket.
Tighten ^
Mechanical fan pulley bracket nuts to 50 Nm (37 lb .ft).
C. Mechanical fan pulley, fan and nuts.
^ Finger tighten only.
D. Fan belt.
Tighten ^
Mechanical fan nuts to 26 Nm (19 lb ft.).
E. Upper radiator fan shroud.
11. Air intake resonator. 12. Right bank spark plug wire boots to spark plugs. 13. Left bank spark
plug wire harness to clip (17) located behind AIR pump. 14. Left bank spark plug wire harness
support channel and bolts/screws (19). Rear bolt / screw (19) is located behind exhaust manifold
takedown.
Slide channel onto bolt / screw (19) then tighten using a 10 mm wrench.
15. Left bank spark plug wire harness boots to spark plugs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Distributor, Ignition >
Distributor Cap > Component Information > Specifications
Distributor Cap: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Distributor, Ignition >
Distributor Cap > Component Information > Service and Repair > Replacement
Distributor Cap: Service and Repair Replacement
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Distributor cap (30). 2. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten ^
Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
3. Vacuum harness assembly to distributor assembly. 4. Connect four-terminal PCM connector to
distributor. 5. Spark plug wire harness assemblies to distributor assembly. 6. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Distributor, Ignition >
Distributor Cap > Component Information > Service and Repair > Replacement > Page 1592
Distributor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Distributor, Ignition > Ignition
Rotor > Component Information > Specifications
Ignition Rotor: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Distributor Rotor Bolt / Screw ..............................................................................................................
....................................................... 0.7 Nm (6 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Distributor, Ignition > Ignition
Rotor > Component Information > Specifications > Page 1596
Ignition Rotor: Service and Repair
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30). 7. Rotor bolts / screws (32) using J 39998 or
equivalent. 8. Rotor assembly (32). 9. Distributor cover (33) and shield (34).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Shield (34) and distributor cover (33). 2. Rotor (32). 3. Rotor bolts / screws (31) using J 39998 or
equivalent.
Tighten ^
Rotor bolts / screws (31) to 0.7 Nm (61 lb in.).
4. Distributor cap (30). 5. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Distributor, Ignition > Ignition
Rotor > Component Information > Specifications > Page 1597
^ Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
6. Vacuum harness assembly to distributor assembly. 7. Connect four-terminal PCM connector to
distributor. 8. Spark plug wire harness assemblies to distributor assembly. 9. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications
Spark Plug: Specifications
Spark Plug Install Torque ....................................................................................................................
........................................................ 27 Nm (20 lb ft.)
Spark Plug Gap ...................................................................................................................................
........................................................ 1.27 mm (0.050")
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications > Page 1601
Spark Plug Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications > Page 1602
Spark Plug: Service Precautions
It is important that technicians wash their hands after handling coated spark plugs and before
smoking. The coating itself is a nonhazardous material and incidental contact will not cause any
adverse affects. However, exposure to polymer vapors (the result of a cigarette being coated from
handling, then burned) may cause flu like symptoms and should be avoided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications > Page 1603
Spark Plug ID
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications > Page 1604
Spark Plug: Description and Operation
Platinum-tipped, resistor-type, tapered-seat spark plugs are used on the engine assembly. No
gasket is used on these tapered-seat spark plugs. When replacing spark plugs, use only the type
specified.
Normal service is assumed to be a mixture of idling, slow speed, and high speed driving.
Occasional or intermittent high-speed driving is needed for good spark plug performance. It gives
increased combustion heat, burning away carbon or oxides that have built up from frequent idling,
or continual stop-and-go driving.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications > Page 1605
Spark Plug: Testing and Inspection
WORN OR DIRTY
Worn or dirty spark plugs may give satisfactory operation at idling speed, but frequently fail at
higher rpm. Faulty spark plugs may cause poor fuel economy, power loss, loss of speed, hard
starting and generally poor engine performance. Follow the scheduled maintenance service
recommendations to assure satisfactory spark plug performance.
NORMAL
Normal spark plug operation will result in brown to grayish - tan deposits appearing on the portion
of the spark plug that projects into the cylinder area. A small amount of red - brown, yellow, and
white powdery material may also be present on the insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels and lubricating oils with additives.
MISFIRING
Engine assemblies which are not running properly are often referred to as "misfiring." This means
the ignition spark is not igniting the fuel/air mixture at the proper time, While other ignition and fuel
system causes must also be considered, possible causes include ignition system conditions which
allow the spark voltage to reach ground in some other manner than by jumping across the air gap
at the tip of the spark plug, leaving the fuel/air mixture unburned. Misfiring may also occur when the
tip of the spark plug becomes overheated and ignites the mixture before the spark jumps. This is
referred to as "pre-ignition."
CARBON FOULING
Carbon fouling of the spark plug is indicated by dry, black carbon (soot) deposits on the portion of
the spark plug in the cylinder. Excessive idling and slow speeds under light engine loads can keep
the spark plug temperatures so low that these deposits are not burned off. Over - rich fuel mixtures
or poor ignition system output may also be the cause.
OIL FOULING
Oil fouling of the spark plug is indicated by wet oily deposits on the portion of the spark plug in the
cylinder. This may be caused by oil getting past worn piston rings. This condition also may occur
during break-in of new or newly overhauled engine assemblies.
DEPOSITS
Deposit fouling of the spark plug occurs when the normal red - brown, yellow or white deposits of
combustion by - products become sufficient to cause misfiring. In some cases, these deposits may
melt and form a shiny glaze on the insulator around the center electrode. If the fouling is found in
only one or two cylinders, valve stem clearances or intake valve seals may be allowing excess
lubricating oil to enter the cylinder, particularly if the deposits are heavier on the side of the spark
plug that was facing the intake valve.
CRACKED OR BROKEN
Cracked or broken insulators may be the result of improper installation or heat shock to the
insulator material. Upper insulators can be broken when a poorly fitting tool is used during
installation or removal, or when the park plug is hit from the outside. Cracks in the upper insulator
may be inside the shell and not visible. Also, the breakage may not cause problems until oil or
moisture penetrates the crack later.
A broken or cracked lower insulator tip (around the center electrode) may result from "heat shock"
(spark plug suddenly operating too hot).
"Heat shock" breakage in the lower insulator tip generally occurs during severe engine operating
conditions (high speeds or heavy loading) and may be caused by over - advanced timing or low
grade fuels. Heat shock refers to a rapid increase in the tip temperature that causes the insulator
material to crack.
Damage during gapping can happen if the gapping tool is pushed against the center electrode or
the insulator around it, causing the insulator to crack. When gapping a spark plug, make the
adjustment by only bending the ground side terminal, keeping the tool clear of other parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Spark Plug > Component
Information > Specifications > Page 1606
Spark Plug: Service and Repair
Spark Plug Assembly
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Spark plug wire harness assemblies
from spark plugs. Refer to "Spark Plug Wire Harness Assembly Replacement" in this section.
^ Note positions of wires before removing.
NOTICE: Clean dirt and debris from spark plug recess areas.
3. Spark plugs from cylinder head assemblies.
NOTICE:
Be sure spark plugs thread smoothly into cylinder head assemblies and are fully seated. Cross threading or failing to fully seat spark plugs can cause overheating of spark plugs, exhaust blow-by,
or thread damage. Follow recommended torque specifications carefully. Over or under - tightening
can also cause severe damage to cylinder head assemblies or spark plug.
Check spark plug gap using a wire type gauge before installing. If spark plug gaps are not adjusted
correctly, engine idle quality may be seriously affected. A wire type gauge must be used (as
opposed to a flat feeler type gauge) to insure an accurate reading.
INSTALL OR CONNECT
1. Spark plugs to cylinder head assemblies.
Tighten ^
Spark plugs to 27 Nm (20 lb ft.).
2. Spark plug wire harness assemblies, routed properly as note during removal.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Compression Check > System
Information > Specifications
Compression Check: Specifications
The lowest reading cylinder should not be less than 70% of the highest and no cylinder reading
should be less than 689 kPa (100 psi). Perform compression test with engine at normal operating
temperature, spark plugs removed and throttle wide open.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Valve Clearance > System
Information > Specifications
Valve Clearance: Specifications
VALVE LASH
Turn rocker arm stud nut until all lash is eliminated (zero lash), then tighten nut additional turn in
1/4 turn increments.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Tune-up and Engine Performance Checks > Valve Clearance > System
Information > Specifications > Page 1613
Valve Clearance: Adjustments
Fig. 5 Valve Lash Adjustment
Adjust valves, Fig.5, with engine at normal operating temperature. Rotate engine until No. 1
cylinder is in position to fire. Adjust exhaust valves 1-3-4-8 and intake valves 1-2-5-7. Crank engine
one complete revolution, then adjust exhaust valves 2-5-6-7 and intake vales 3-4-6-8.
On all engines, the following procedure, performed with the engine running, should only be
performed if readjustment is required.
1. After engine has been warmed up to normal operating temperature, remove valve cover and
install a new valve cover gasket. 2. With engine running at idle speed, back off valve rocker arm
nut until rocker arm starts to clatter. 3. Turn rocker arm nut down slowly until clatter just stops. This
is the zero lash position. 4. Turn nut down 1/4 additional turn and pause 10 seconds until engine
runs smoothly. Repeat additional 1/4 turns, pausing 10 seconds each time,
until nut has been turned down the number of turns listed in "Valve Clearance Specifications chart
from the zero lash position. This preload adjustment must be done slowly to allow lifter to adjust
itself to prevent the possibility of interference between valve head and top of piston, which might
result in internal damage and/or bent push rods. Noisy lifters should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Technical Service Bulletins > Engine
- Drive Belt Misalignment Diagnostics
Drive Belt: Technical Service Bulletins Engine - Drive Belt Misalignment Diagnostics
INFORMATION
Bulletin No.: 08-06-01-008A
Date: July 27, 2009
Subject: Diagnosing Accessory Drive Belt / Serpentine Belt Noise and Availability and Use of
Kent-Moore EN-49228 Laser Alignment Tool - Drive Belt
Models:
2010 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2,
H3 Vehicles 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add a model year and update the Tool Information.
Please discard Corporate Bulletin Number 08-06-01-008 (Section 06 - Engine).
Background
Several aftermarket companies offer laser alignment tools for accessory drive systems that can be
very helpful in eliminating drive belt noise as a result of misaligned pulleys. Typically pricing ranges
from $160 - $200.
EN-49228 Laser Alignment Tool - Drive Belt
The GM Tool program has now made available a competitive, simple to use and time-saving laser
tool to assist in achieving precise alignment of the drive belt pulleys. This optional tool removes the
guesswork from proper pulley alignment and may serve to reduce comebacks from:
- Drive Belt Noise
- Accelerated Drive Belt Wear
- Drive Belt Slippage
Instructions
The instructions below are specific only to the truck Gen IV V-8 family of engines. These
instructions are only for illustrative purposes to show how the tool may be used. Universal
instructions are included in the box with the Laser Alignment Tool - Drive Belt.
Caution
- Do not look directly into the beam projected from the laser.
- Use caution when shining the laser on highly polished or reflective surfaces. Laser safety glasses
help reduce laser beam glare in many circumstances.
- Always use laser safety glasses when using the laser. Laser safety glasses are not designed to
protect eyes from direct laser exposure.
1. Observe and mark the serpentine belt orientation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Technical Service Bulletins > Engine
- Drive Belt Misalignment Diagnostics > Page 1618
2. Remove the serpentine belt from the accessory drive system.
3. Install the tool onto the power steering pulley. Position the legs of the tool into the outer grooves
of the pulley, farthest from the front of the
engine.
4. Install the retaining cord around the pulley and to the legs of the tool.
5. Put on the laser safety glasses provided with the tool. 6. Depress the switch on the rear of the
tool to activate the light beam. 7. Rotate the power steering pulley as required to project the light
beam onto the crankshaft balancer pulley grooves. 8. Inspect for proper power steering pulley
alignment.
- If the laser beam projects onto the second rib or raised area (1), the pulleys are aligned properly.
- If the laser beam projects more than one-quarter rib 0.9 mm (0.035 in) mis-alignment, adjust the
position of the power steering pulley as required.
- Refer to SI for Power Steering Pulley Removal and Installation procedures.
9. Install the serpentine belt to the accessory drive system in the original orientation.
10. Operate the vehicle and verify that the belt noise concern is no longer present.
Tool Information
Please visit the GM service tool website for pricing information or to place your order for this tool.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Technical Service Bulletins > Engine
- Drive Belt Misalignment Diagnostics > Page 1619
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Technical Service Bulletins > Engine
- Drive Belt Misalignment Diagnostics > Page 1620
Drive Belt: Technical Service Bulletins Engine - Serpentine Drive Belt Wear Information
Bulletin No.: 04-06-01-013
Date: April 29, 2004
INFORMATION
Subject: Information on Serpentine Belt Wear
Models: 2004 and Prior Passenger Cars and Trucks 2003-2004 and Prior HUMMER H2
All current GM vehicles designed and manufactured in North America were assembled with
serpentine belts that are made with an EPDM material and should last the life of the vehicle. It is
extremely rare to observe any cracks in EPDM belts and it is not expected that they will require
maintenance before 10 years or 240,000 km (150,000 mi) of use.
Older style belts, which were manufactured with a chloroprene compound, may exhibit cracks
depending on age. However, the onset of cracking typically signals that the belt is only about
halfway through its usable life.
A good rule of thumb for chloroprene-based belts is that if cracks are observed 3 mm (1/8 in) apart,
ALL AROUND THE BELT, the belt may be reaching the end of its serviceable life and should be
considered a candidate for changing. Small cracks spaced at greater intervals should not be
considered as indicative that the belt needs changing.
Any belt that exhibits chunking should be replaced.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Specifications > Serpentine Belt
Tension Specification
Drive Belt: Specifications Serpentine Belt Tension Specification
Engines equipped with serpentine belts have an automatic tensioner. No adjustment of this is
necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Specifications > Serpentine Belt
Tension Specification > Page 1623
Drive Belt: Specifications Air Conditioning Belt Tension Specification
New .....................................................................................................................................................
............................................................... 105-125 Lbs
Used ....................................................................................................................................................
............................................................... 105-125 Lbs
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Drive Belt > Component Information > Specifications > Page 1624
Drive Belt: Service and Repair
Fig. 16 Serpentine Drive Belt Routing
SERPENTINE DRIVE BELT BELT ROUTING
Refer to Fig.16. for serpentine belt routing diagrams.
BELT REPLACEMENT
1. Disconnect battery ground cable. 2. On models with mechanical cooling fan, proceed as follows:
a. Rotate mechanical cooling fan tensioner pulley clockwise using a suitable 13 mm wrench while
sliding belt from tensioner pulley. b. Remove fan belt from pulleys. c. Remove radiator outlet nuts at
air conditioning compressor.
3. On all models, rotate tensioner pulley clockwise using a suitable 9/16 offset wrench while sliding
belt from tensioner, then remove serpentine
drive belt.
4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Cleaner Fresh Air Duct/Hose >
Component Information > Locations
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > Customer Interest for Air Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T Shift/Driveability Concerns/MIL ON
Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > Customer Interest for Air Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T Shift/Driveability Concerns/MIL ON > Page 1638
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > All Technical Service Bulletins for Air Filter Element: > 04-07-30-013B > Feb > 07 > Engine,
A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > All Technical Service Bulletins for Air Filter Element: > 04-07-30-013B > Feb > 07 > Engine,
A/T - Shift/Driveability Concerns/MIL ON > Page 1644
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > Page 1645
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > Page 1646
Air Filter Element: Service and Repair
Air Ducting
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Air Cleaner Housing > Air Filter Element > Component Information
> Technical Service Bulletins > Page 1647
REMOVE OR DISCONNECT
1. Loosen wing nuts at front of air cleaner housing. 2. Lift air cleaner lid, Mass Air Flow (MAF)
sensor and resonator as a unit. 3. Remove air filter element.
INSTALL OR CONNECT
1. Install air filter element. 2. Move air cleaner lid, MAF sensor and resonator into place. 3. Tighten
wing nuts. 4. Check clamps at MAF sensor and tighten if necessary. 5. Check joints between duct,
resonators and throttle body for possible air leaks. Repair if necessary.
NOTICE: If the Mass Air Flow (MAF) sensor is installed backwards, the system will go rich. An
arrow cast into the plastic portion of the sensor indicates proper air flow direction. The arrow must
point toward the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Cabin Air Filter > Component Information > Locations
Cabin Air Filter: Locations
This vehicle does not contain a factory installed cabin air filter.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Fuel Filter > Fuel Pressure Release > System Information >
Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Filters > Oil Filter, Engine > Component Information > Technical Service
Bulletins > Engine - Noise/Damage Oil Filter Application Importance
Oil Filter: Technical Service Bulletins Engine - Noise/Damage Oil Filter Application Importance
INFORMATION
Bulletin No.: 07-06-01-016B
Date: July 27, 2009
Subject: Information on Internal Engine Noise or Damage After Oil Filter Replacement
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
Supercede: This bulletin is being updated to add model years. Please discard Corporate Bulletin
Number 07-06-01-016A (Section 06 - Engine/Propulsion System).
Important Engine damage that is the result of an incorrect or improperly installed engine oil filter is
not a warrantable claim. The best way to avoid oil filter quality concerns is to purchase ACDelco(R)
oil filters directly from GMSPO.
Oil filter misapplication may cause abnormal engine noise or internal damage. Always utilize the
most recent parts information to ensure the correct part number filter is installed when replacing oil
filters. Do not rely on physical dimensions alone. Counterfeit copies of name brand parts have been
discovered in some aftermarket parts systems. Always ensure the parts you install are from a
trusted source. Improper oil filter installation may result in catastrophic engine damage.
Refer to the appropriate Service Information (SI) installation instructions when replacing any oil
filter and pay particular attention to procedures for proper cartridge filter element alignment. If the
diagnostics in SI (Engine Mechanical) lead to the oil filter as the cause of the internal engine noise
or damage, dealers should submit a field product report. Refer to Corporate Bulletin Number
02-00-89-002I (Information for Dealers on How to Submit a Field Product Report).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Hoses > System Information > Service Precautions
Hoses: Service Precautions
SERVICE PRECAUTIONS
To prevent vehicle damage, always observe the following precautions: After servicing a hose, check for leaks before and after test driving the vehicle.
- Always use the correct size hose. Do not use standard sized hose in place of metric hose or vice
versa.
Always use the correct type of hose. Never use vacuum hose in place of fuel hose. Never use
heater hose in place of PCV hose.
- When replacing hoses which are attached to the engine on one end and the frame or body on the
other end, always leave sufficient length to compensate for engine movement (from torque).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Brake Fluid > Component Information > Technical Service Bulletins
> Brake Fluid - Level & Filling Recommendations
Brake Fluid: Technical Service Bulletins Brake Fluid - Level & Filling Recommendations
File In Section: 05 - Brakes
Bulletin No.: 00-05-22-004
Date: May, 2000
INFORMATION
Subject: Brake Fluid Level and Filling Recommendations
Models: 2001 and Prior Passenger Cars and Trucks
Many dealers and after-market repair shops advertise multi-point fluid "top-ups" in conjunction with
oil changes or regular maintenance packages. These offers often include adding brake fluid to the
master cylinder reservoir. There are only two reasons why the brake fluid level in the brake
reservoir might go down. The first is that the brake fluid level goes down an acceptable level during
normal brake lining wear. When the linings are replaced, the fluid will return to it's original level.
The second possible reason for a low fluid level is that fluid is leaking out of the brake system. If
fluid is leaking, the brake system requires repair and adding additional fluid will not correct the leak.
If the system was properly filled during delivery of the vehicle, no additional fluid should be required
under most circumstances between brake pad and/or shoe replacements. This information can be
reinforced with the customer by referring them to the Brake Fluid section of their vehicle's Owner's
Manual.
Guidelines
GM vehicles have incorporated a variety of brake fluid reservoir styles. The following guidelines are
restricted to the plastic bodied fluid reservoirs and do not affect the original service
recommendations for the older style metal bodied units.
You may encounter both black plastic and translucent style reservoirs. You may have reservoirs
with:
^ A MAX fill mark only
^ A MIN fill mark only
^ Both MAX and MIN marks
The translucent style reservoirs do not have to have the covers removed in order to view the fluid
level. It is a good practice not to remove the reservoir cover unless necessary to reduce the
possibility of contaminating the system. Use the following guidelines to assist in determining the
proper fluid level.
Important:
When adding brake fluid, use Delco Supreme II(R) Brake Fluid, GM P/N 12377967 or equivalent
brand bearing the DOT-3 rating only.
Important:
At no time should the fluid level be allowed to remain in an overfilled condition. Overfilling the brake
reservoir may put unnecessary stress on the seals and cover of the reservoir. Use the following
guidelines to properly maintain the fluid level. If the reservoir is overfilled, siphon out the additional
fluid to comply with the guidelines below.
Important:
If under any circumstance the brake fluid level is extremely low in the reservoir or the BRAKE
warning indicator is illuminated, the brake system should be checked for leaks and the system
repaired in addition to bringing the fluid level up to the recommended guidelines outlined below. A
leaking brake system will have reduced braking performance and will eventually not work at all.
Important:
Some vehicles have reservoirs that are very sensitive to brake fluid levels and may cause the
BRAKE indicator to flicker on turns as the fluid approaches the minimum required level. If you
encounter a vehicle with this concern, increase the fluid level staying within the guidelines outlined
below.
^ If the reservoir has a MAX level indicator, the reservoir should be returned to the MAX marking
only at the time new brake pads and/or shoes are installed. If the reservoir fluid level is at the
half-way point or above do not attempt to add additional brake fluid during routine fluid checks.
^ If the reservoir has both MAX and MIN indicators, the fluid level should be maintained above the
MIN indicator during routine fluid checks and returned to the MAX indication only after new brake
pads and/or shoes are installed.
^ For reservoirs with only a MIN indication, the fluid level should be maintained above the MIN
indicator during routine fluid checks. Return the
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Brake Fluid > Component Information > Technical Service Bulletins
> Brake Fluid - Level & Filling Recommendations > Page 1667
reservoir fluid level to full only after installing new brake pads and/or shoes. A full reservoir is
indicated on translucent, snap cover reservoirs by a fluid level even with the top level of the view
window imprinted into the side of the reservoir. On screw top models in black or translucent plastic,
the full level is just below the bottom of the filler neck.
Parts Information
Part Number Description
12377967 Brake Fluid
Parts are currently available from GMSPO.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Brake Fluid > Component Information > Technical Service Bulletins
> Page 1668
Brake Fluid: Specifications
Brake System DOT 3
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Clutch Fluid > Component Information > Specifications > Capacity
Specifications
Clutch Fluid: Capacity Specifications
Fill the clutch master cylinder to the "Full" or "MAX" mark on the reservoir. Do not overfill.
Caution: Should accidental spillage occur, rinse the area thoroughly with water. Pay special
attention to any electrical wires, parts, harnesses, rubber or painted surfaces.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Clutch Fluid > Component Information > Specifications > Capacity
Specifications > Page 1673
Clutch Fluid: Fluid Type Specifications
Hydraulic Clutch Fluid
........................................................................................................................................ GM P/N
12345347 or DOT 3 Brake Fluid
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Cooling System - Coolant Recycling Information
Coolant: Technical Service Bulletins Cooling System - Coolant Recycling Information
Bulletin No.: 00-06-02-006D
Date: August 15, 2006
INFORMATION
Subject: Engine Coolant Recycling and Warranty Information
Models: 2007 and Prior GM Passenger Cars and Trucks (Including Saturn) 2007 and Prior
HUMMER Vehicles 2005-2007 Saab 9-7X
Attention:
Please address this bulletin to the Warranty Claims Administrator and the Service Manager.
Supercede:
This bulletin is being revised to adjust the title and Include Warranty Information. Please discard
Corporate Bulletin Number 00-06-02-006C (Section 06 - Engine/Propulsion System).
Coolant Reimbursement Policy
General Motors supports the use of recycled engine coolant for warranty repairs/service, providing
a GM approved engine coolant recycling system is used. Recycled coolant will be reimbursed at
the GMSPO dealer price for new coolant plus the appropriate mark-up. When coolant replacement
is required during a warranty repair, it is crucial that only the relative amount of engine coolant
concentrate be charged, not the total diluted volume. In other words: if you are using two gallons of
pre-diluted (50:50) recycled engine coolant to service a vehicle, you may request reimbursement
for one gallon of GM Goodwrench engine coolant concentrate at the dealer price plus the
appropriate warranty parts handling allowance.
Licensed Approved DEX-COOL(R) Providers
Important:
USE OF NON-APPROVED VIRGIN OR RECYCLED DEX-COOL(R) OR DEVIATIONS IN THE
FORM OF ALTERNATE CHEMICALS OR ALTERATION OF EQUIPMENT, WILL VOID THE GM
ENDORSEMENT, MAY DEGRADE COOLANT SYSTEM INTEGRITY AND PLACE THE
COOLING SYSTEM WARRANTY UNDER JEOPARDY.
Shown in Table 1 are the only current licensed and approved providers of DEX-COOL(R). Products
that are advertised as "COMPATIBLE" or "RECOMMENDED" for use with DEX-COOL(R) have not
been tested or approved by General Motors. Non-approved coolants may degrade the
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Cooling System - Coolant Recycling Information > Page 1678
coolant system integrity and will no longer be considered a 5 yr/150,000 mile (240,000 km) coolant.
Coolant Removal Services/Recycling
The tables include all coolant recycling processes currently approved by GM. Also included is a
primary phone number and demographic information. Used DEX-COOL(R) can be combined with
used conventional coolant (green) for recycling. Depending on the recycling service and/or
equipment, it is then designated as a conventional 2 yr/30,000 mile (50,000 km) coolant or
DEX-COOL(R) 5 yr/150,000 mile (240,000 km) coolant. Recycled coolants as designated in this
bulletin may be used during the vehicle(s) warranty period.
DEX-COOL(R) Recycling
The DEX-COOL(R) recycling service listed in Table 2 has been approved for recycling waste
engine coolants (DEX-COOL) or conventional) to DEX-COOL(R) with 5 yr/150,000 mile (240,000
km) usability. Recycling Fluid Technologies is the only licensed provider of Recycled
DEX-COOL(R) meeting GM6277M specifications and utilizes GM approved inhibitor packages.
This is currently a limited program being monitored by GM Service Operations which will be
expanded as demand increases.
Conventional (Green) Recycling
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Cooling System - Coolant Recycling Information > Page 1679
Processes shown in the Table 3 are capable of recycling waste engine coolants (DEX-COOL(R) or
conventional) to a conventional (green) coolant. Recycling conventional coolant can be
accomplished at your facility by a technician using approved EQUIPMENT (listed by model number
in Table 3), or by an approved coolant recycling SERVICE which may recycle the coolant at your
facility or at an offsite operation. Refer to the table for GM approved coolant recyclers in either of
these two categories. Should you decide to recycle the coolant yourself, strict adherence to the
operating procedures is imperative. Use ONLY the inhibitor chemicals supplied by the respective
(GM approved) recycling equipment manufacturer.
Sealing Tablets
Cooling System Sealing Tablets (Seal Tabs) should not be used as a regular maintenance item
after servicing an engine cooling system. Discoloration of coolant can occur if too many seal tabs
have been inserted into the cooling system. This can occur if seal tabs are repeatedly used over
the service life of a vehicle. Where appropriate, seal tabs may be used if diagnostics fail to repair a
small leak in the cooling system. When a condition appears in which seal tabs may be
recommended, a specific bulletin will be released describing their proper usage.
Water Quality
The integrity of the coolant is dependent upon the quality of DEX-COOL(R) and water.
DEX-COOL(R) is a product that has enhanced protection capability as well as an extended service
interval. These enhanced properties may be jeopardized by combining DEX-COOL(R) with poor
quality water. If you suspect the water in your area of being poor quality, it is recommended you
use distilled or de-ionized water with DEX-COOL(R).
"Pink" DEX-COOL(R)
DEX-COOL(R) is orange in color to distinguish it from other coolants. Due to inconsistencies in the
mixing of the dyes used with DEX-COOL(R), some batches may appear pink after time. The color
shift from orange to pink does not affect the integrity of the coolant, and still maintains the 5
yr/150,000 mile (240,000 km) service interval.
Back Service
Only use DEX-COOL(R) if the vehicle was originally equipped with DEX-COOL(R).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Cooling System - Coolant Recycling Information > Page 1680
Contamination
Mixing conventional green coolant with DEX-COOL(R) will degrade the service interval from 5
yrs./150,000 miles (240,000 km) to 2 yrs./30,000 miles (50,000 km) if left in the contaminated
condition. If contamination occurs, the cooling system must be flushed twice immediately and
re-filled with a 50/50 mixture of DEX-COOL(R) and clean water in order to preserve the enhanced
properties and extended service interval of DEX-COOL(R).
After 5 years/150,000 miles (240,000 km)
After 5 yrs/150,000 miles (240,000 km), the coolant should be changed, preferably using a coolant
exchanger. If the vehicle was originally equipped with DEX-COOL(R) and has not had problems
with contamination from non-DEX-COOL(R) coolants, then the service interval remains the same,
and the coolant does not need to be changed for another 5 yrs/150,000 miles (240,000 km)
Equipment (Coolant Exchangers)
The preferred method of performing coolant replacement is to use a coolant exchanger. A coolant
exchanger can replace virtually all of the old coolant with new coolant. Coolant exchangers can be
used to perform coolant replacement without spillage, and facilitate easy waste collection. They
can also be used to lower the coolant level in a vehicle to allow for less messy servicing of cooling
system components. It is recommended that you use a coolant exchanger with a vacuum feature
facilitates removing trapped air from the cooling system. This is a substantial time savings over
repeatedly thermo cycling the vehicle and topping-off the radiator. The vacuum feature also allows
venting of a hot system to relieve system pressure. Approved coolant exchangers are available
through the GMDE (General Motors Dealer Equipment) program.
For refilling a cooling system that has been partially or fully drained for repairs other than coolant
replacement, the Vac-N-Fill Coolant Refill Tool (GE-47716) is recommended to facilitate removal of
trapped air from the cooling system during refill.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Cooling System - Coolant Recycling Information > Page 1681
Coolant: Technical Service Bulletins Engine Coolant - Information on Back Service
File In Section: 6 - Engine
Bulletin No: 53-62-02
Date: November, 1995
Subject: DEX-COOL(TM) Engine Coolant - Information on Back service
Models: 1994-95 Passenger Cars and Trucks
A new extended-life engine coolant called DEX-COOL(TM) is currently being used in all General
Motors' vehicles (excluding Chevrolet Geo and Saturn). Refer to bulletin 53-62-01 for general
service information.
Backservice
DEX-COOL(TM) may be used in General Motors vehicles originally built with conventional (green)
coolant with the following considerations:
^ Vehicles eligible for back service are 1994 and 1995 models (excluding 1994 J Body with 4
cylinder engines).
^ The service interval for DEX-COOL(TM) introduced into an older model vehicle originally built
with "green" coolant will be 2 years/30,000 miles (50,000 Km) (not 5 years/100,000 miles (160,000
Km)).
^ All the "green" coolant must be removed from the cooling system by means of a system flush.
This may be accomplished with a water flushing device or a GMDE waterless coolant changer (use
a unit dedicated to "green" coolant, not DEX-COOL TM).
Important:
When using a GMDE waterless coolant changer, conduct the procedure twice, once with water,
and once with DEX-COOL(TM)
Backservice with DEX-COOL(TM) is advocated because of enhanced water pump seal durability
experienced with this coolant.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Cooling System - Coolant Recycling Information > Page 1682
Coolant: Technical Service Bulletins Extended Life Engine Coolant - DEX-COOL(TM)
FILE IN SECTION: 6 - Engine
BULLETIN NO.: 53-62-01
DATE: June, 1995
SUBJECT: New Extended Life Engine Coolant Known as DEX-COOL(TM)
MODELS: 1995 Passenger Cars and Trucks
A new extended life engine coolant known as "DEX-COOL(TM)" will be used in all General Motors
vehicles. Some trucks will be filled with DEX-COOL TM beginning in late May; most vehicles will
convert in July, 1995 with the remaining vehicles to convert by January, 1996. Most of these
vehicles will be 1995 models. All production for 1996 models will utilize DEX-COOL(TM). It is
imperative to note the following about DEX-COOL(TM) engine coolant:
^ IT IS ORANGE IN COLOR TO DISTINGUISH IT FROM CONVENTIONAL COOLANT.
^ THE SERVICE CHANGE INTERVAL ON VEHICLES WHICH ARE BUILT WITH DEX-COOL(TM)
IS 5 YEARS/100,000 MILES, WHICHEVER OCCURS FIRST.
^ TO MAINTAIN FULL CORROSION PROTECTION DURABILITY, DEX-COOL (TM) MUST NOT
BE MIXED WITH CONVENTIONAL (CONTAINING SILICATE) ENGINE COOLANTS.
^ DEX-COOL(TM) IS AN ETHYLENE GYLCOL BASED PRODUCT, THEREFORE, BOIL AND
FREEZE PROTECTION ARE MEASURED IN THE SAME FASHION AS CONVENTIONAL
COOLANTS.
TO FULLY REALIZE ITS MANY ADVANTAGES, DEX-COOL(TM) MUST NEVER BE MIXED
WITH CONVENTIONAL COOLANTS.
It is particularly important to top-off new vehicles with DEX-COOL(TM) DEX-COOL(TM) forms a
protective film on aluminum surfaces, however, if a vehicle with less than 3,000 miles is topped-off
with conventional coolant, aluminum corrosion may occur. DEX-COOL(TM) CAN BECOME
CONTAMINATED BY INADVERTENTLY TOPPING-OFF WITH CONVENTIONAL COOLANT,
ADDING CONVENTIONAL COOLANT TO THE RADIATOR, OR EVEN IF FILL/DRAIN
CONTAINERS ARE SHARED BETWEEN COOLANTS.
If contamination occurs on a new vehicle (i.e. during vehicle prep), the cooling system must be
immediately drained and refilled with DEX-COOL(TM) If contamination with conventional coolant
occurs after the vehicle has been driven for at least 3,000 miles, no short-term problems will occur;
however, the service change interval will be reduced from 5 years/100,000 miles to 2 years/30,000
miles. More information on DEX-COOL(TM) engine coolant service procedures can be found in the
1996 Service Manuals and a video tape which will be issued by STG.
Vehicles which contain DEX-COOL(TM) can be identified by a special underhood label which
states "USE DEX-COOL(TM) COOLANT ONLY. .. meeting Spec. 6277M". They may also be
identified by the coolant's orange color and the information contained in the Owner's Manual.
REGARDING COOLANT RECYCLING
Engine coolant recycling is affected by DEX-COOL(TM) as follows. Used DEX-COOL(TM) can be
mixed into your "used" conventional coolant storage vessel and the mixture recycled in the same
manner as you are accustomed to. This recycled mixture of conventional and DEX-COOL(TM)
coolant must be used as a 2 year/30,000 mile conventional coolant and should not be used in
vehicles originally equipped with DEX-COOL(TM) When servicing vehicles originally equipped with
DEX-COOL(TM), use only Goodwrench-DEX-COOL(TM) Additional research will be conducted to
evaluate the feasibility of recycling DEX-COOL(TM) to DEX-COOL(TM) in the near future.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Coolant > Component Information > Technical Service Bulletins >
Page 1683
Coolant: Specifications
Mixture
..........................................................................................................................................................
50/50 of water and ethylene glycol antifreeze
Capacity
Without Heavy-Duty Radiator
..............................................................................................................................................................
13.5 liters (14.3 qt) With Heavy-Duty Radiator ....................................................................................
............................................................................... 13.8 liters (14.6 qt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> A/T - DEXRON(R)-VI Fluid Information
Fluid - A/T: Technical Service Bulletins A/T - DEXRON(R)-VI Fluid Information
INFORMATION
Bulletin No.: 04-07-30-037E
Date: April 07, 2011
Subject: Release of DEXRON(R)-VI Automatic Transmission Fluid (ATF)
Models:
2008 and Prior GM Passenger Cars and Light Duty Trucks 2003-2008 HUMMER H2 2006-2008
HUMMER H3 2005-2007 Saturn Relay 2005 and Prior Saturn L-Series 2005-2007 Saturn ION
2005-2008 Saturn VUE with 4T45-E 2005-2008 Saab 9-7X Except 2008 and Prior Chevrolet Aveo,
Equinox Except 2006 and Prior Chevrolet Epica Except 2007 and Prior Chevrolet Optra Except
2008 and Prior Pontiac Torrent, Vibe, Wave Except 2003-2005 Saturn ION with CVT or AF23 Only
Except 1991-2002 Saturn S-Series Except 2008 and Prior Saturn VUE with CVT, AF33 or 5AT
(MJ7/MJ8) Transmission Only Except 2008 Saturn Astra
Attention:
DEXRON(R)-VI Automatic Transmission Fluid (ATF) is the only approved fluid for warranty repairs
for General Motors transmissions/transaxles requiring DEXRON(R)-III and/or prior DEXRON(R)
transmission fluids.
Supercede: This bulletin is being revised to update information. Please discard Corporate Bulletin
Number 04-07-30-037D (Section 07 - Transmission/Transaxle).
MANUAL TRANSMISSIONS / TRANSFER CASES and POWER STEERING
The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle
that previously required DEXRON(R)-III for a manual transmission or transfer case should now use
P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Some manual
transmissions and transfer cases require a different fluid. Appropriate references should be
checked when servicing any of these components.
Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid.
Consult the Parts Catalog, Owner's Manual, or Service Information (SI) for fluid recommendations.
Some of our customers and/or General Motors dealerships/Saturn Retailers may have some
concerns with DEXRON(R)-VI and DEXRON(R)-III Automatic Transmission Fluid (ATF) and
transmission warranty claims. DEXRON(R)-VI is the only approved fluid for warranty repairs for
General Motors transmissions/transaxles requiring DEXRON(R)-III and/or prior DEXRON(R)
transmission fluids (except as noted above). Please remember that the clean oil reservoirs of the
J-45096 - Flushing and Flow Tester machine should be purged of DEXRON(R)-III and filled with
DEXRON(R)-VI for testing, flushing or filling General Motors transmissions/transaxles (except as
noted above).
DEXRON(R)-VI can be used in any proportion in past model vehicles equipped with an automatic
transmission/transaxle in place of DEXRON(R)-III (i.e. topping off the fluid in the event of a repair
or fluid change). DEXRON(R)-VI is also compatible with any former version of DEXRON(R) for use
in automatic transmissions/transaxles.
DEXRON(R)-VI ATF
General Motors Powertrain has upgraded to DEXRON(R)-VI ATF with the start of 2006 vehicle
production.
Current and prior automatic transmission models that had used DEXRON(R)-III must now only use
DEXRON(R)-VI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> A/T - DEXRON(R)-VI Fluid Information > Page 1688
All 2006 and future model transmissions that use DEXRON(R)-VI are to be serviced ONLY with
DEXRON(R)-VI fluid.
DEXRON(R)-VI is an improvement over DEXRON(R)-III in the following areas:
* These ATF change intervals remain the same as DEXRON(R)-III for the time being.
2006-2008 Transmission Fill and Cooler Flushing
Some new applications of the 6L80 six speed transmission will require the use of the J 45096 Flushing and Flow Tester to accomplish transmission fluid fill. The clean oil reservoir of the
machine should be purged of DEXRON(R)-III and filled with DEXRON(R)-VI.
Parts Information
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> A/T - DEXRON(R)-VI Fluid Information > Page 1689
Fluid - A/T: Technical Service Bulletins A/T - Water Or Coolant Contamination Information
INFORMATION
Bulletin No.: 08-07-30-035B
Date: November 01, 2010
Subject: Information on Water or Ethylene Glycol in Transmission Fluid
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks with Automatic Transmission
Supercede: This bulletin is being revised to update model years. Please discard Corporate Bulletin
Number 08-07-30-035A (Section 07 - Transmission/Transaxle).
Water or ethylene glycol in automatic transmission fluid (ATF) is harmful to internal transmission
components and will have a negative effect on reliability and durability of these parts. Water or
ethylene glycol in ATF will also change the friction of the clutches, frequently resulting in shudder
during engagement or gear changes, especially during torque converter clutch engagement.
Indications of water in the ATF may include:
- ATF blowing out of the transmission vent tube.
- ATF may appear cloudy or, in cases of extreme contamination, have the appearance of a
strawberry milkshake.
- Visible water in the oil pan.
- A milky white substance inside the pan area.
- Spacer plate gaskets that appear to be glued to the valve body face or case.
- Spacer plate gaskets that appear to be swollen or wrinkled in areas where they are not
compressed.
- Rust on internal transmission iron/steel components.
If water in the ATF has been found and the source of the water entry has not been identified, or if a
leaking in-radiator transmission oil cooler is suspected (with no evidence of cross-contamination in
the coolant recovery reservoir), a simple and quick test kit is available that detects the presence of
ethylene glycol in ATF. The "Gly-Tek" test kit, available from the Nelco Company, should be
obtained and the ATF tested to make an accurate decision on the need for radiator replacement.
This can help to prevent customer comebacks if the in-radiator transmission oil cooler is leaking
and reduce repair expenses by avoiding radiator replacement if the cooler is not leaking. These
test kits can be obtained from:
Nelco Company
Test kits can be ordered by phone or through the website listed above. Orders are shipped
standard delivery time but can be shipped on a next day delivery basis for an extra charge. One
test kit will complete 10 individual fluid sample tests. For vehicles repaired under warranty, the cost
of the complete test kit plus shipping charges should be divided by 10 and submitted on the
warranty claim as a net item.
The transmission should be repaired or replaced based on the normal cost comparison procedure.
Important If water or coolant is found in the transmission, the following components MUST be
replaced.
- Replace all of the rubber-type seals.
- Replace all of the composition-faced clutch plates and/or bands.
- Replace all of the nylon parts.
- Replace the torque converter.
- Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
Important The following steps must be completed when repairing or replacing.
Flush and flow check the transmission oil cooler using J 45096. Refer to Corporate Bulletin Number
02-07-30-052F- Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096
TransFlow.
- Thoroughly inspect the engine cooling system and hoses and clean/repair as necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> A/T - DEXRON(R)-VI Fluid Information > Page 1690
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> A/T - DEXRON(R)-VI Fluid Information > Page 1691
Fluid - A/T: Technical Service Bulletins A/T - DEXRON III Fluid Introduction
File In Section: 0 - General Information
Bulletin No.: 57-02-01
Date: March, 1995
SERVICE MANUAL UPDATE
Subject: Section 0 - General Information - DEXRON(R)-III Transmission Fluid Introduction
Models: 1995 and Prior Passenger Cars and Trucks
General Motors has phased in a new automatic transmission fluid, DEXRON(R)-III, that does not
need replacing under normal service. DEXRON(R)-III is designed to help the transmission deliver
the best possible performance under all conditions. Refer to Figure 1.
The improvements in DEXRON(R)-III include better friction stability, more high temperature
oxidation stability and better material compatibility. DEXRON(R)-III has the same low temperature
fluidity as DEXRON(R)-IIE, for better transmission performance in cold weather.
DEXRON(R)-IIE and DEXRON(R)-III are fully compatible.
DEXRON(R)-III is fully compatible with any General Motors passenger vehicle or light truck with
automatic transmission and built since 1949.
Dealers should require their supplier to include the DEXRON(R)-III license number on all automatic
transmission fluid invoices.
Starting February 1, 1994 DEXRON(R)-III was phased into all North American assembly plants.
DEXRON(R)-III fluid is available from GMSPO (see fluid numbers below):
U.S.
1 Quart 12346143
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> A/T - DEXRON(R)-VI Fluid Information > Page 1692
1 Gallon 12346144
55 Gallon 12346145
In Canada
1 Liter 10952622
4 Liter 10952623
200 Liter 10952624
The 1995 Automatic Transmission/Transaxle fluid change intervals are the following:
(1994 and prior should use the schedules as written in the Owner's Manual.)
If the vehicle is mainly driven under one or more of these conditions:
In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police car or delivery service.
Change the fluid and filter every 50,000 miles (63,000 km).
If the vehicle is not used mainly under any of these conditions, the fluid and filter do not require
periodic changing for vehicles under 8,600 GVWR.
Vehicles over 8,600 GVWR change the fluid and filter every 50,000 miles (83,000 km) regardless
of driving conditions.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> Page 1693
Fluid - A/T: Specifications
Fluid Type
........................................................................................................................................................
DEXRON-IIE or DEXRON-III auto. trans.
Capacity
Drain & Refill ........................................................................................................................................
.............................................. 4.7 liters (10.0 pt) Overhaul ..................................................................
.......................................................................................................................... 10.6 liters (22.4 pt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - A/T > Component Information > Technical Service Bulletins
> Page 1694
Fluid - A/T: Service and Repair
NOTE: The following procedure has been modified by a technical service bulletin.
1. Raise and support vehicle. 2. Proceed as follows:
a. Loosen transmission mount to support attaching nut. b. Loosen two bolts attaching right side of
transmission support to frame rail. c. Remove two bolts attaching left side transmission support to
frame rail. d. Using suitable transmission jack, support and slightly raise transmission. e. Slide
transmission support rearward enough to access rear oil pan attaching bolts.
3. Place drain pan under transmission oil pan, loosen pan bolts on front of pan, pry carefully with
screwdriver to loosen oil pan, and allow fluid to
drain.
4. Remove remaining oil pan bolts, oil pan, and gasket. 5. Drain fluid from pan, then clean pan and
dry thoroughly with compressed air. 6. Remove oil filter to valve body bolt, then the filter and
gasket. 7. Install new filter seal into case, then new filter and attaching bolt. 8. Install new gasket on
oil pan, then install oil pan and tighten bolts to specification. 9. Lower vehicle and add five quarts of
automatic transmission fluid through filler tube.
10. With selector lever in park and parking brake applied, start engine and let idle. Do not race
engine. 11. Move selector lever through each range, return to park position, check fluid, and add
additional fluid to bring level between dimples on dipstick.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - M/T > Component Information > Specifications
Fluid - M/T: Specifications
Fluid Type
........................................................................................................................................................
DEXRON-IIE or DEXRON-III auto. trans.
Capacity
Drain & Refill ........................................................................................................................................
.............................................. 4.7 liters (10.0 pt) Overhaul ..................................................................
.......................................................................................................................... 10.6 liters (22.4 pt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - Differential > Component Information > Technical Service
Bulletins > Drivetrain - Recommended Axle Lubricant
Fluid - Differential: Technical Service Bulletins Drivetrain - Recommended Axle Lubricant
File In Section: 0 - General Information
Bulletin No.: 76-02-02A
Date: October, 1998
INFORMATION
Subject: Recommended Axle Lubricant
Models: 1999 and Prior Rear Wheel Drive Passenger Cars, Light and Medium Duty Trucks, and
Four Wheel Drive Vehicles
This bulletin is being revised to add the 1998 and 1999 Model Years and add Vehicle Line and
Recommended Axle Lubricant Information. Please discard Corporate Bulletin Number 76-02-02
(Section 0 - General Information).
The following tables provide the latest information on recommended axle lubricant.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - Differential > Component Information > Technical Service
Bulletins > Drivetrain - Recommended Axle Lubricant > Page 1702
Parts Information
Parts are currently available from GMSPO.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Fluid - Differential > Component Information > Technical Service
Bulletins > Page 1703
Fluid - Differential: Specifications
Fluid Type
Standard Differential ^ SAE 80W-90 GL-5 gear lubricant Limited Slip Differential ^ Lubricant
additive (GM P/N 1052358) and ^ SAE 80W-90 GL-5 gear lubricant
Capacity
Drain and Refill ....................................................................................................................................
................................................. 1.7 liters (3.5 pt) Additive ...................................................................
.................................................................................................................... 118 milliliters (4 fl oz)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Engine Oil > Component Information > Technical Service Bulletins
> Engine - GM dexos 1 and dexos 2(R) Oil Specifications
Engine Oil: Technical Service Bulletins Engine - GM dexos 1 and dexos 2(R) Oil Specifications
INFORMATION
Bulletin No.: 11-00-90-001
Date: March 14, 2011
Subject: Global Information for GM dexos1(TM) and GM dexos2(TM) Engine Oil Specifications for
Spark Ignited and Diesel Engines, Available Licensed Brands, and Service Fill for Adding or
Complete Oil Change
Models:
2012 and Prior GM Passenger Cars and Trucks Excluding All Vehicles Equipped with
Duramax(TM) Diesel Engines
GM dexos 1(TM) Information Center Website
Refer to the following General Motors website for dexos 1(TM) information about the different
licensed brands that are currently available: http://www.gmdexos.com
GM dexos 1(TM) Engine Oil Trademark and Icons
The dexos(TM) specification and trademarks are exclusive to General Motors, LLC.
Only those oils displaying the dexos‹›(TM) trademark and icon on the front label meet the
demanding performance requirements and stringent quality standards set forth in the dexos‹›(TM)
specification.
Look on the front label for any of the logos shown above to identify an authorized, licensed dexos
1(TM) engine oil.
GM dexos 1(TM) Engine Oil Specification
Important General Motors dexos 1(TM) engine oil specification replaces the previous General
Motors specifications GM6094M, GM4718M and GM-LL-A-025 for most GM gasoline engines. The
oil specified for use in GM passenger cars and trucks, PRIOR to the 2011 model year remains
acceptable for those previous vehicles. However, dexos 1(TM) is backward compatible and can be
used in those older vehicles.
In North America, starting with the 2011 model year, GM introduced dexos 1(TM) certified engine
oil as a factory fill and service fill for gasoline engines. The reasons for the new engine oil
specification are as follows:
- To meet environmental goals such as increasing fuel efficiency and reducing engine emissions.
- To promote long engine life.
- To minimize the number of engine oil changes in order to help meet the goal of lessening the
industry's overall dependence on crude oil.
dexos 1(TM) is a GM-developed engine oil specification that has been designed to provide the
following benefits:
- Further improve fuel economy, to meet future corporate average fuel economy (CAFE)
requirements and fuel economy retention by allowing the oil to maintain its fuel economy benefits
throughout the life of the oil.
- More robust formulations for added engine protection and aeration performance.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Engine Oil > Component Information > Technical Service Bulletins
> Engine - GM dexos 1 and dexos 2(R) Oil Specifications > Page 1708
- Support the GM Oil Life System, thereby minimizing the replacement of engine oil, before its life
has been depleted.
- Reduce the duplication of requirements for a large number of internal GM engine oil
specifications.
International Lubricants Standardization and Approval Committee (ILSAC)
GF-5 Standard
In addition to GM dexos 1(TM), a new International Lubricants Standardization and Approval
Committee (ILSAC) standard called GF-5, was introduced in October 2010.
- There will be a corresponding API category, called: SN Resource Conserving. The current GF-4
standard was put in place in 2004 and will become obsolete in October 2011. Similar to dexos
1(TM), the GF-5 standard will use a new fuel economy test, Sequence VID, which demands a
statistically significant increase in fuel economy versus the Sequence VIB test that was used for
GF-4.
- It is expected that all dexos 1(TM) approved oils will be capable of meeting the GF-5 standard.
However, not all GF-5 engine oils will be capable of meeting the dexos 1(TM) specification.
- Like dexos(TM), the new ILSAC GF-5 standard will call for more sophisticated additives. The API
will begin licensing marketers during October 2010, to produce and distribute GF-5 certified
products, which are expected to include SAE 0W-20, 0W-30, 5W-20, 5W-30 and 10W-30 oils.
Corporate Average Fuel Economy (CAFE) Requirements Effect on Fuel Economy
Since CAFE standards were first introduced in 1974, the fuel economy of cars has more than
doubled, while the fuel economy of light trucks has increased by more than 50 percent. Proposed
CAFE standards call for a continuation of increased fuel economy in new cars and trucks. To meet
these future requirements, all aspects of vehicle operation are being looked at more critically than
ever before.
New technology being introduced in GM vehicles designed to increase vehicle efficiency and fuel
economy include direct injection, cam phasing, turbocharging and active fuel management (AFM).
The demands of these new technologies on engine oil also are taken into consideration when
determining new oil specifications. AFM for example can help to achieve improved fuel economy.
However alternately deactivating and activating the cylinders by not allowing the intake and
exhaust valves to open contributes to additional stress on the engine oil.
Another industry trend for meeting tough fuel economy mandates has been a shift toward lower
viscosity oils.
dexos 1(TM) will eventually be offered in several viscosity grades in accordance with engine needs:
SAE 0W-20, 5W-20, 0W-30 and 5W-30.
Using the right viscosity grade oil is critical for proper engine performance. Always refer to the
Maintenance section of a vehicle Owner Manual for the proper viscosity grade for the engine being
serviced.
GM Oil Life System in Conjunction With dexos (TM) Supports Extended Oil Change Intervals
To help conserve oil while maintaining engine protection, many GM vehicles are equipped with the
GM Oil Life System. This system can provide oil change intervals that exceed the traditional 3,000
mile (4,830 km) recommendation.
The dexos (TM) specification, with its requirements for improved oil robustness, compliments the
GM Oil Life System by supporting extended oil change intervals over the lifetime of a vehicle.
If all GM customers with GM Oil Life System equipped vehicles would use the system as intended,
GM estimates that more than 100 million gallons of oil could be saved annually.
GM dexos 2(TM) Information Center Website
Refer to the following General Motors website for dexos 2(TM) information about the different
licensed brands that are currently available: http://www.gmdexos.com
GM dexos 2(TM) Engine Oil Trademark and Icons
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Engine Oil > Component Information > Technical Service Bulletins
> Engine - GM dexos 1 and dexos 2(R) Oil Specifications > Page 1709
The dexos (TM) specification and trademarks are exclusive to General Motors, LLC.
Only those oils displaying the dexos (TM) trademark and icon on the front label meet the
demanding performance requirements and stringent quality standards set forth in the dexos
(TM)specification.
Look on the front label for any of the logos shown above to identify an authorized, licensed dexos
2(TM) engine oil.
GM dexos 2(TM) Engine Oil Specification
- dexos 2(TM) is approved and recommended by GM for use in Europe starting in model year 2010
vehicles, regardless of where the vehicle was manufactured.
- dexos 2(TM) is the recommended service fill oil for European gasoline engines.
Important The Duramax(TM) diesel engine is the exception and requires lubricants meeting
specification CJ-4.
- dexos 2(TM) is the recommended service fill oil for European light-duty diesel engines and
replaces GM-LL-B-025 and GM-LL-A-025.
- dexos 2(TM) protects diesel engines from harmful soot deposits and is designed with limits on
certain chemical components to prolong catalyst life and protect expensive emission reduction
systems. It is a robust oil, resisting degradation between oil changes and maintaining optimum
performance longer.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Engine Oil > Component Information > Specifications > Capacity
Specifications
Engine Oil: Capacity Specifications
Fluid Type ............................................................................................................................................
.................................................. API service SH/SG
Capacity
Without filter change ............................................................................................................................
................................................. 3.8 liters (4.0 qt) With filter change ....................................................
.............................................................................................................................. 4.7 liters (5.0 qt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment
Refrigerant: Technical Service Bulletins A/C - Refrigerant Recovery/Recycling/Equipment
Bulletin No.: 08-01-38-001
Date: January 25, 2008
INFORMATION
Subject: Information On New GE-48800 CoolTech Refrigerant Recovery/Recharge Equipment
Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2008 and
Prior HUMMER H2, H3 2005-2008 Saab 9-7X
Attention:
This bulletin is being issued to announce the release of GM approved Air Conditioning (A/C)
Refrigerant Recovery and Recharging Equipment that meets the new Society of Automotive
Engineers (SAE) J2788 Refrigerant Recovery Standards. The ACR2000 (J-43600) cannot be
manufactured in its current state after December 2007 and will be superseded by GE-48800.
The new J2788 standard does not require that GM Dealers replace their ACR2000 units.
ACR2000's currently in use are very capable of servicing today's refrigerant systems when used
correctly and can continue to be used. Details regarding the new SAE J2788 standard are outlined
in GM Bulletin 07-01-38-004.
Effective February 1 2008, new A/C Refrigerant Recovery/Recharging equipment (P/N GE-48800)
will be released as a required replacement for the previously essential ACR2000 (J-43600). This
equipment is SAE J2788 compliant and meets GM requirements for A/C Refrigerant System
Repairs on all General Motors vehicles, including Hybrid systems with Polyolester (POE)
refrigerant oil. This equipment will not be shipped as an essential tool to GM Dealerships.
In addition, this equipment is Hybrid compliant and designed to prevent oil cross contamination
when servicing Hybrid vehicles with Electric A/C Compressors that use POE refrigerant oil.
The ACR2000 (J-43600) will need to be retrofitted with a J-43600-50 (Hose - ACR2000 Oil Flush
Loop) to be able to perform Hybrid A/C service work. All Hybrid dealers will receive the J-43600-50,
with installation instructions, as a component of the Hybrid essential tool package. Dealerships that
do not sell Hybrids, but may need to service Hybrids, can obtain J-43600-50 from SPX Kent Moore.
Refer to GM Bulletin 08-01-39-001 for the ACR2000 Hose Flush procedure.
The High Voltage (HV) electric A/C compressor used on Two Mode Hybrid vehicles uses a
Polyolester (POE) refrigerant oil instead of a Polyalkylene Glycol (PAG) synthetic refrigerant oil.
This is due to the better electrical resistance of the POE oil and its ability to provide HV isolation.
Failure to flush the hoses before adding refrigerant to a Hybrid vehicle with an electric A/C
compressor may result in an unacceptable amount of PAG oil entering the refrigerant system. It
may cause a Battery Energy Control Module Hybrid Battery Voltage System Isolation Lost
Diagnostic Trouble Code (DTC P1AE7) to be set. Additionally, the A/C system warranty will be
voided.
Warranty Submission Requirements
The Electronically Generated Repair Data (snapshot summary) and printer functions have been
eliminated from the GE-48800. The VGA display and temperature probes were eliminated to
reduce equipment costs. As a result, effective immediately the 18 digit "Snapshot/Charge
Summary" code is no longer required for Air Conditioning (A/C) refrigerant system repairs that are
submitted for warranty reimbursement. The charge summary data from before and after system
repairs will continue to required, but documented on the repair order only. Both high and low
pressures and the recovery and charge amounts should be noted during the repair and entered on
the repair order. If using ACR2000 (J-43600), the "Snapshot/Charge Summary" printouts should
continue to be attached to the shops copy of the repair order.
The labor codes that are affected by this requirement are D3000 through D4500.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1716
Refrigerant: Technical Service Bulletins A/C - Contaminated R134A Refrigerant
Bulletin No.: 06-01-39-007
Date: July 25, 2006
INFORMATION
Subject: Contaminated R134a Refrigerant Found on Market for Automotive Air-Conditioning
Systems
Models: 2007 and Prior GM Passenger Cars and Trucks (including Saturn) 2007 and Prior
HUMMER H2, H3 2007 and Prior Saab 9-7X
Attention:
This bulletin should be directed to the Service Manager as well as the Parts Manager.
Commercially Available Contaminated R134a Refrigerant
Impurities have been found in new commercially available containers of R134a. High levels of
contaminates may cause decreased performance, and be detrimental to some air-conditioning
components. Accompanying these contaminates has been high levels of moisture.
Tip:
Excessive moisture may cause system concerns such as orifice tube freeze-up and reduced
performance.
Industry Reaction: New Industry Purity Standards
Due to the potential availability of these lower quality refrigerants, the Society of Automotive
Engineers (SAE), and the Air Conditioning and Refrigeration Industry (ARI) are in the process of
instituting reliable standards that will be carried on the labels of future R134a refrigerant containers.
This identifying symbol will be your assurance of a product that conforms to the minimum standard
for OEM Automotive Air-Conditioning use.
How Can You Protect Yourself Today?
It is recommended to use GM or ACDelco(R) sourced refrigerants for all A/C repair work. These
refrigerants meet General Motors own internal standards for quality and purity, insuring that your
completed repairs are as good as the way it left the factory.
Parts Information
The part numbers shown are available through GMSPO or ACDelco(R). The nearest ACDelco(R)
distributor in your area can be found by calling 1-800-223-3526 (U.S. Only).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1717
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1718
Refrigerant: Technical Service Bulletins A/C - Refrigerant Recovery/Recharge Equipment
File In Section: 01 - HVAC
Bulletin No.: 99-01-38-006A
Date: May, 2000
WARRANTY ADMINISTRATION
Subject: J-43600 ACR 2000 Essential Refrigerant Recovery/Recharge Equipment
Models: 1993-2000 Passenger Cars and Light Duty Trucks with R-134a Refrigerant
This bulletin is being revised to change the effective date and to update the text. Please discard
Corporate Bulletin Number 99-01-38-006 (Section 01 - HVAC).
Effective June 1, 2000, the use of J-43600 ACR 2000 will be required on all repairs that require A/C
system recovery and are reimbursable by GM. Additionally, GM highly recommends that J-43600
ACR 2000 be used on all GM cars and trucks for customer paid A/C repairs.
Important:
Also effective June 1, 2000, the "Add" time for all air conditioning recovery is revised to 0.5 hours
for front systems and 0.7 hours for front/rear dual systems (RPO C69 or C34). After June 1, 2000,
all air conditioning claims submitted with the 0.9 hours "Add" time will be rejected for "labor hours
excessive".
After the completion of repairs (charging), the ACR 2000 will prompt the user to perform a snapshot
of the air conditioning system operating data. The snapshot includes:
^ Maximum high side pressure.
^ Minimum low side pressure.
^ Duct outlet temperatures (2).
^ Refrigerant purity information.
This information is captured on a paper printout and in a warranty code.
For all GM paid repairs, the paper printout should be attached to the shop copy of the repair order.
The warranty code must be submitted in the warranty claim information in the comments field. The
code enables the reporting of valuable information about the repair to GM for product quality
improvement. Claims submitted without this information may be subject to review and subsequent
debit.
The required use of J-43600 ACR 2000 raises the question of the acceptable uses for any existing
recovery/recycle equipment that GM dealers are currently using. GM recognizes that many of the
previously essential ACR4's are reaching the end of their useful life. There are several alternatives
for existing equipment that may be considered:
^ Use the existing equipment as customer paid recovery only equipment. Example: Collision repair
area.
^ Use the existing equipment as a scavenger unit for contaminated A/C systems.
^ Sell the existing units to repair facilities outside the GM dealer network.
^ Discontinue the use of the existing units if the repair/maintenance costs exceed the value of the
equipment.
^ Donate the existing equipment to local technical schools.
^ Dedicate the ACR4 to A/C system flushing, using the J-42939 Flush Adapter.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1719
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1720
Technical Service Bulletin # 631209 Date: 960501
A/C - R12 or R134a Service Recommendations
File In Section: 1 - HVAC
Bulletin No.: 63-12-09
Date: May, 1996
INFORMATION
Subject: Service Issues for Vehicles with R12 or R134a Air Conditioning Systems
Models: 1988-96 Passenger Cars and Trucks
R12 Service Recommendations
As you know, production of R12 refrigerant ceased on December 31, 1995. Although R12 will no
longer be manufactured, there is a reserve supply of R12 available. This reserve, along with strict
A/C repair service adherence to proper refrigerant recycling procedures, should assure continued
availability to meet consumers' needs.
R12 can and should continue to be used to service vehicles built with R12 A/C systems as long as
it is available. If R12 is no longer available or affordable, a system retrofit utilizing R134a is
recommended. R134a IS THE ONLY SUBSTITUTE REFRIGERANT RECOMMENDED BY GM
FOR USE IN GM VEHICLE A/C SYSTEMS, AND THEN ONLY AFTER FOLLOWING THE
PROPER RETROFIT PROCEDURES FOR THE SPECIFIC MODEL. All new vehicle
manufacturers have chosen R134a for retrofit. One of the key reasons is to protect both the service
industry and consumers from the high costs that would result from purchasing equipment
necessary to service multiple refrigerants. This position also reduces the threat of recycled
refrigerant contamination.
GM currently offers a simple, low cost R12 to R134a retrofit on many of its late model, front wheel
drive passenger cars. Dealers should discuss this capability with owners of these specific models,
listed in Retrofit Corporate Bulletin # 43-12-07D, whenever a repair to the A/C refrigerant system is
required. Early retrofit of these specific models will aid in prolonging availability of the R12 supply
and provide dealer service technicians the opportunity to become more familiar with the proper
procedures for performing a retrofit.
Remember - R12 and R134a refrigerant are not interchangeable! They cannot be mixed together.
In fact, despite the claims of some refrigerant manufacturers, no proposed R12 refrigerant
substitute can be added to, mixed with or used to "top off" an R12 system. Under provisions of law
covering the service of refrigerants, mixing dissimilar refrigerant products during service is
prohibited.
To Summarize GM R12 Service Policy
1. Service R12 vehicles with good quality new or recycled R12 as long as it is available.
2. Purchase R12 from a reliable supplier. GMSPO has a supply of high quality R12 available.
Dealers are requested to use only R12 supplied by GMSPO for warranty repairs. This high quality
refrigerant will insure system performance and avoid the possibility of introducing contaminated
material into the customer's A/C system.
3. Carefully test recovered R12 using the PureGuard monitor. On recovery equipment not
protected by the PureGuard, always test the recovery cylinder prior to recharging a vehicle A/C
system.
4. Discuss the R12 to R134a retrofit option with owners of GM vehicles listed in Retrofit Corporate
Bulletin # 43-12-07D. Provide owner with a copy of the pamphlet "Converting Your Auto Air
Conditioning System to Use the New Refrigerant".
5. Become familiar with retrofit procedures and exercise care in the handling of dissimilar
refrigerants to prevent contamination.
R134A Service Recommendations
When servicing a previously retrofitted vehicle, there is concern that if all of the R12 is not
completely removed prior to the retrofit procedure, it could contaminate your R134a equipment and
recovery tank when a subsequent A/C repair is performed. Although the number of retrofits being
performed today is minimal, the volume will increase as R12 prices rise.
GM Service Technology Group is in the process of field testing a new R134a refrigerant purity
tester similar to the PureGuard R12 refrigerant tester you now use. This new tool will mount to your
ACR4 R134a Recovery Recycle and Recharge cart and sample all R134a refrigerant prior to
recovery. It is expected that testing of this tool will be completed this year.
This new tool, the Pureguard 2, will also test vehicles and your recycle tank for air contamination,
which is threatening A/C system performance. High levels of air have been found in the recovery
tanks on a number of R12 and R134a recovery carts. Air contamination is caused by improper
recovery
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1721
procedures and short-cutting refrigerant recycling times. Use the following procedure for testing
and correcting air contamination in your A/C service equipment.
1. Make certain that the ACR4 equipment has not been used for at least 12 hours. It is
recommended that the equipment be left in an area where the temperature will remain constant
overnight to allow the temperature of the refrigerant in the tank to stabilize.
2. Record the surrounding air temperature next to the ACR4 refrigerant tank.
Important:
A major assumption is that the ambient air temperature next to the tank represents the refrigerant
temperature in the tank. Failure to take care in measuring the temperature could result in
unnecessary work.
3. Close both liquid (blue) and vapor (red) valves on the ACR4 tank.
4. Disconnect low side (blue) service hose from the back of the ACR4.
5. Slowly disconnect the tank vapor hose (red) from the back of the ACR4 and connect it to the low
side service port.
6. Open the vapor (red) valve on the tank and record the tank pressure on the low side gage.
7. Restore hoses to the original position.
8. Referring to the Table, find the ambient temperature measured in Step 2. Compare the pressure
reading from Step 6 to the "maximum allowable pressure". If the pressure reading from Step 6 is
less than the "maximum allowable pressure", no further action is necessary.
Important:
The closer the tank pressure is to the desired tank pressure, the better the A/C system will perform.
9. If the pressure reading from Step 6 exceeds the maximum allowable pressure from the Table,
open both tank valves and operate the ACR4 through 4 or 5 evacuation cycles. This will activate
the automatic air purge to lower the tank pressure.
Important:
Station should not be connected to vehicle.
10. Repeat the tank pressure checking procedure the next day to determine if the pressure has
been reduced to acceptable levels. If the tank pressure has been reduced but is not acceptable,
cycle with ACR4 through more evacuation cycles and recheck the next day. Continue process until
acceptable pressure is obtained. If the tank pressure is not reduced through the evacuation cycling,
then Kent-Moore should be contacted at 1-800-345-2233.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1722
Refrigerant: Technical Service Bulletins A/C - R134a Leak Detection With Tracer Dye
File In Section: 1 - HVAC
Bulletin No.: 43-12-15
Date: November, 1994
Subject: R134a Leak Detection with Tracer Dye
Models: All 1993-95 Vehicles with OEM R134a Systems All R12 Vehicles Retrofitted to R134a
Systems
R134a refrigerant is uniquely different from R12 refrigerant and requires some changes in the
repair methods, tools and materials used in A/C service. Two important differences between R134a
and R12 which affect the technicians ability to locate refrigerant leaks are:
1. The R134a molecule is smaller than the R12 molecule and therefore will leak through smaller
openings. For the same size opening the smaller R134a molecule will leak out faster than the R12.
2. R134a refrigerant does not contain chlorine which the older R12 electronic leak detectors found
very easy to identify. Many of today's electronic leak detectors have difficulty locating small R134a
refrigerant leaks.
In order to insure the highest quality in A/C system service, the J 39400 electronic leak detector
was released as an essential tool for all GM dealers. This is the only refrigerant leak detector
approved by GM for service on R134a vehicles. If maintained properly (Reference Bulletin No.
431218) and used in accordance with Service Manual procedures, the J 39400 will provide the
most accurate and efficient method of locating R134a refrigerant leaks under most conditions.
If the technician cannot find the leak with the J 39400 and the system is known to have lost charge,
a new fluorescent leak tracer dye Kent-Moore* P/N J 41447, has been released that mixes with the
R134a PAG oil. This dye is detectable through the use of an ultraviolet (black) light and glows
yellow/green at the leak location (similar to using dye in engine leak detection). J 41447 IS THE
ONLY APPROVED DYE BY GENERAL MOTORS. Not all R134a dyes are compatible with GM's
PAG oil. Some dyes decrease the oil viscosity or chemically react with the oil. Use of alternate
products may affect system reliability and cause premature compressor failure.
Note:
THIS DYE IS NOT TO BE USED IN R-12 SYSTEMS.
Unlike mineral oil, the R134a PAG oil has special properties the technician should keep in mind.
1. PAG oil is water soluble and traces of PAG oil found at leaking joints are subject to "washing
out". Condensation on refrigerant lines or the evaporator core may wash the PAG oil and leak dye
off the line or off the core and out the condensate drain. This can make some leaks harder to find
using the dye detector. Fluorescence at the drain opening would indicate a core leak.
2. Use of the R134a tracer dye requires time. Depending upon the leak rate, it may take between
15 minutes and 7 days for the leak to become visible.
3. The dye, mixed with the PAG oil, is retained in the system and is detectable for 2+ years. Do not
double or triple charge the system with dye as this may cause reliability concerns. Use only the 1/4
oz. charge.
The dye has a refrigerant leak detection notice sticker included with the package. Complete the
sticker information and place near the charge label.
Dye Injection R-134a dye can be injected two ways:
1. With the A/C system charged, use the instructions provided with the new R134a leak dye
injection tool, J 41436.
2. With A/C system discharged, add dye into the newly replaced component assembly.
It is important to note that it is normal to find oil traces at the compressor shaft seal during
compressor operation, some oil will hydraulically seep past the shaft seal. This does not mean that
the shaft seal is defective or that the refrigerant has leaked. Refrigerant leaks at the shaft seal
should be verified with the electronic leak detector (J 39400) following the procedure detailed in the
Service Manual. If, however, the amount of oil is excessive, the shaft seal is suspect and should be
replaced. (For example, refrigerant oil has coated the clutch plate edge at gap between clutch and
pulley, or oil slinging has occurred-oil line shows on underside of hood, etc.).
Also, after working on A/C components with dye, it is important to wipe the joint and/or access
ports clean of any residual dye with GM solvent (GM
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> A/C - Refrigerant Recovery/Recycling/Equipment > Page 1723
P/N 1050436) to prevent false diagnosis at a later point.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Parts Information GM solvent, P/N 1050436, is currently available from GMSPO.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Technical Service Bulletins
> Page 1724
Refrigerant: Specifications
Refrigerant Capacity, Lbs. ...................................................................................................................
................................................ 0.79 kg. (1 lb. 12 oz.)
Refrigerant Type ..................................................................................................................................
...................................................................... R-134a
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Description and Operation
> Refrigerant R-12
Refrigerant: Description and Operation Refrigerant R-12
DESCRIPTION
It is colorless and odorless both as a gas and a liquid. Since it boils (vaporizes) at -21.7° F, it will
usually be in a vapor state when being handled in a repair shop. But if a portion of the liquid coolant
should come in contact with the hands or face, note that its temperature momentarily will be at
least -22° F.
WARNING: Protective goggles should be worn when opening any refrigerant lines. If liquid coolant
does touch the eyes, bathe the eyes quickly in cold water, then apply a bland disinfectant oil to the
eyes. See an eye doctor.
WARNING: When checking a system for leaks with a torch type leak detector, do not breathe the
vapors coming from the flame. Do not discharge refrigerant in the area of a live flame. A poisonous
phosgene gas is produced when R-12 is burned. While the small amount of gas produced by a leak
detector is not harmful unless inhaled directly at the flame, the quantity of refrigerant released into
the air when a system is purged can be extremely dangerous if allowed to come into contact with
an open flame.
WARNING: Never allow the temperature of refrigerant drums to exceed 125° F. The excessive
increase in temperature will cause a corresponding increase in pressure which may cause the
safety plug to release or the drum to burst.
If it is necessary to heat a drum of refrigerant when charging a system, the drum should be placed
in water no hotter than 125° F. Never use a blow torch or other open flame. If possible, a pressure
release mechanism should be attached before the drum is heated.
When connecting and disconnecting service gauges on an A/C system, ensure gauge hand valves
are fully closed and that compressor service valves, if equipped, are in the back-seated (fully
counterclockwise) position. Do not disconnect gauge hoses from service port adapters, if used,
while gauges are connected to A/C system. To disconnect hoses, always remove adapter from
service port. Do not disconnect hoses from gauge manifold while connected to A/C system, as
refrigerant will be rapidly discharged.
After disconnecting gauge lines, check the valve areas to be sure service valves are correctly
seated and Schrader valves, if used, are not leaking.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant > Component Information > Description and Operation
> Refrigerant R-12 > Page 1727
Refrigerant: Description and Operation Refrigerant-134a
R-134a refrigerant is a non toxic, nonflammable, clear and odorless liquefied gas.
CAUTION: R-134a refrigerant is not compatible with R-12 refrigerant. Even small amounts of R-12
in a R-134a system will cause lubricant contamination, compressor failure or improper A/C
performance. Never add R-12 to a R-134a system.
WARNING: Avoid breathing R-134a refrigerant and lubricant vapor or mist. Exposure may irritate
eyes, nose and throat. Use only approved service equipment to discharge R-134a systems.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant Oil > Component Information > Technical Service
Bulletins > A/C - New PAG Oil
Refrigerant Oil: Technical Service Bulletins A/C - New PAG Oil
Bulletin No.: 02-01-39-004B
Date: November 16, 2005
INFORMATION
Subject: New PAG Oil Released
Models: 2006 and Prior GM Passenger Cars and Trucks (Including Saturn) 2003-2006 HUMMER
H2 2006 HUMMER H3 2005-2006 Saab 9-7X
Built With R-134a Refrigeration System
All Air Conditioning Compressor Types (Excluding R4 and A6 Type Compressors)
Supercede:
This bulletin is being revised to change the PAG oil part number used for R4 and A6 compressors
with R-134a refrigerant systems. Please discard Corporate Bulletin Number 02-01-39-004A
(Section 01 - HVAC).
All General Motors vehicles built with R-134a refrigerant systems shall now be serviced with GM
Universal PAG Oil (excluding vehicles equipped with an R4 or A6 compressor).
R4 and A6 compressors with R-134a refrigerant systems shall use PAG OIL, GM P/N 12356151
(A/C Delco part number 15-118) (in Canada, use P/N 10953486).
Important:
The PAG oil referenced in this bulletin is formulated with specific additive packages that meet
General Motors specifications and use of another oil may void the A/C systems warranty.
Use this new PAG oil when servicing the A/C system on the vehicles listed above. Oil packaged in
an 8 oz tube should be installed using A/C Oil Injector, J 45037. Refer to the HVAC Section of
Service Information for detailed information on Oil Balancing and Capacities.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant Oil > Component Information > Specifications >
Capacity Specifications
Refrigerant Oil: Capacity Specifications
Compressor Model [02] .......................................................................................................................
........................................................... HD6/HR6-HE Oil Charge (FL. Oz.) When Replacing
Component
Compressor .........................................................................................................................................
............................................................................. [03]
Evaporator ...........................................................................................................................................
................................................................................. 3 Condenser ......................................................
..............................................................................................................................................................
........ 1 Accumulator .............................................................................................................................
......................................................................................... 3.5
[02] Fixed displacement compressor. [03] Drain oil from old compressor and measure, then drain
new compressor. If more than one ounce is drained from old compressor, add same amount
to new compressor. If less than one ounce is drained from compressor, add two ounces.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fluids > Refrigerant Oil > Component Information > Specifications >
Capacity Specifications > Page 1734
Refrigerant Oil: Fluid Type Specifications
REFRIGERANT OIL TYPE
^ R-134a PAG (Polyalkaline Glycol) synthetic refrigerant oil (GM Part No. 12345923) or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Brake Bleeding > System Information > Service and Repair > With ABS
System
Brake Bleeding: Service and Repair With ABS System
Manual Bleeding
Fig. 210 Brake System Manual Bleed.
NOTE: Pressure bleeding is recommended for all hydraulic systems. However, if a pressure
bleeder is unavailable, use the following procedure.
CAUTION: Brake fluid damages painted surfaces. Immediately clean any spilled fluid.
1. Remove vacuum reserve by pumping brakes several times with engine off. 2. Fill master cylinder
reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let
reservoir fall below half full. 3. If necessary, bleed master cylinder as follows:
a. Disconnect master cylinder forward brake line connection until fluid flows from reservoir.
Reconnect and tighten brake line. b. Instruct an assistant to slowly depress brake pedal one time
and hold. c. Crack open front brake line connection again, purging air from cylinder. d. Retighten
connection and slowly release brake pedal. e. Wait 15 seconds, then repeat until all air is purged. f.
Bleed the rearward (nearest the cowl) brake line connection by repeating preceding steps.
4. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 5. Proceed to appropriate wheel first and follow set sequence according
to Wheel Bleed Sequence. See: Wheel Bleed Sequence 6. Place transparent tube over bleeder
valve, then allow tube to hang down into transparent container, Fig. 210. Ensure end of tube is
submerged in
clean brake fluid.
7. Instruct an assistant to slowly depress brake pedal one time and hold. 8. Crack open bleeder
valve, purging air from cylinder. Retighten bleeder screw and slowly release pedal. 9. Wait 15
seconds, then repeat preceding bleed steps. Repeat these steps until all air is bled from system.
Pressure Bleeding
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Brake Bleeding > System Information > Service and Repair > With ABS
System > Page 1739
Fig. 210 Brake System Manual Bleed.
Fig. 21 Installing Pressure Bleeder Adapter
1. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 2. Using a diaphragm type pressure bleeder, install suitable bleeder
adapter to master cylinder, Fig. 211. 3. Charge bleeder ball to 20-25 psi. 4. Connect pressure
bleeder line to adapter. 5. Open line valve on pressure bleeder, then depress bleed-off valve on
adapter until a small amount of brake fluid is released. 6. Raise and support vehicle. 7. Proceed to
appropriate wheel first and follow set sequence according to Wheel Bleeding Sequence. See:
Wheel Bleed Sequence 8. Place transparent tube over bleeder valve, then allow tube to hang down
into transparent container, Fig. 210. Ensure end of tube is submerged in
clean brake fluid.
9. Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from
line.
Wheel Bleed Sequence
If manual bleeding, RR-LR-RF-LF; if pressure bleeding, bleed front brakes together and rear
brakes together.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Brake Bleeding > System Information > Service and Repair > With ABS
System > Page 1740
Brake Bleeding: Service and Repair Without ABS System
Manual
Fig. 210 Brake System Manual Bleed.
NOTE: Pressure bleeding is recommended for all hydraulic systems. However, if a pressure
bleeder is unavailable, use the following procedure. Brake fluid damages painted surfaces.
Immediately clean any spilled fluid.
1. Remove vacuum reserve by pumping brakes several times with engine off. 2. Fill master cylinder
reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let
reservoir fall below half full. 3. If necessary, bleed master cylinder as follows:
a. Disconnect master cylinder forward brake line connection until fluid flows from reservoir.
Reconnect and tighten brake line. b. Instruct an assistant to slowly depress brake pedal one time
and hold. c. Crack open front brake line connection again, purging air from cylinder. d. Retighten
connection and slowly release brake pedal. e. Wait 15 seconds, then repeat until all air is purged. f.
Bleed the rearward (nearest the cowl) brake line connection by repeating steps a through e.
4. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 5. Proceed to appropriate wheel first and follow set sequence according
to Wheel Bleeding Sequence. 6. Place transparent tube over bleeder valve, then allow tube to
hang down into transparent container, Fig. 16. Ensure end of tube is submerged in
clean brake fluid.
7. Instruct an assistant to slowly depress brake pedal one time and hold. 8. Crack open bleeder
valve, purging air from cylinder. Retighten bleeder screw and slowly release pedal. 9. Wait 15
seconds, then repeat steps 7 and 8. Repeat these steps until all air is bled from system.
Pressure
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Brake Bleeding > System Information > Service and Repair > With ABS
System > Page 1741
Fig. 21 Installing Pressure Bleeder Adapter
Fig. 210 Brake System Manual Bleed.
1. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 2. Using a diaphragm type pressure bleeder, install suitable bleeder
adapter to master cylinder, Fig. 17. 3. Charge bleeder ball to 20-25 psi. 4. Connect pressure
bleeder line to adapter. 5. Open line valve on pressure bleeder, then depress bleed-off valve on
adapter until a small amount of brake fluid is released. 6. Raise and support vehicle. 7. Proceed to
appropriate wheel first and follow set sequence according to Wheel Bleeding Sequence. 8. Place
transparent tube over bleeder valve, then allow tube to hang down into transparent container, Fig.
16. Ensure end of tube is submerged in
clean brake fluid.
9. Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from
line.
Front Disc Brakes
NOTE: Pressure bleeding is recommended for all hydraulic disc brake systems.
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. On
vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid
level in master cylinder during bleeding operation.
Never use brake fluid that has been drained from hydraulic system when bleeding the brakes. Be
sure the disc brake pistons are returned to their normal positions and that the shoe and lining
assemblies are properly seated. Before driving the vehicle, check brake operation to be sure that a
firm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Brake Bleeding > System Information > Service and Repair > With ABS
System > Page 1742
pedal has been obtained.
Rear Disc Brakes
NOTE: Pressure bleeding is recommended for all hydraulic disc brake systems.
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. On
vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid
level in master cylinder during bleeding operation.
Never use brake fluid that has been drained from hydraulic system when bleeding the brakes. Be
sure the disc brake pistons are returned to their normal positions and that the shoe and lining
assemblies are properly seated. Before driving the vehicle, check brake operation to be sure that a
firm pedal has been obtained.
Wheel Bleeding Sequence
Rear wheel drive models: if manual bleeding, RR-LR-RF-LF; if pressure bleeding, bleed front
brakes together and rear brakes together. Front wheel drive models: RR-LF-LR-RF
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Air Bag(s) Arming and Disarming > System Information > Service and
Repair > Air Bag Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Air Bag(s) Arming and Disarming > System Information > Service and
Repair > Air Bag Disarming and Arming > Page 1747
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Circuit Breaker > Component Information >
Locations
Fuse Block Details: Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Circuit Breaker > Component Information >
Locations > Page 1752
Fuse Block Details: Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Technical
Service Bulletins > Electrical - Aftermarket Fuse Warning
Fuse: Technical Service Bulletins Electrical - Aftermarket Fuse Warning
Bulletin No.: 07-08-45-002
Date: September 05, 2007
ADVANCED SERVICE INFORMATION
Subject: Service Alert: Concerns With Aftermarket Fuses in GM Vehicles
Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2008 and
Prior HUMMER H2, H3 2008 and Prior Saab 9-7X
Concerns with Harbor Freight Tools "Storehouse" Branded Blade Type Fuses
General Motors has become aware of a fuse recall by Harbor Freight Tools/Storehouse for a
variety of aftermarket fuses. In two cases, these fuses have not provided protection for the wiring
system of the vehicles they were customer installed in.
Upon testing the 15 amp version, it was found that the fuse still would not "open" when shorted
directly across the battery terminals.
How to Identify These Fuses
Packed in a 120 piece set, the fuse has a translucent, hard plastic, blue body with the amperage
stamped into the top. There are no white painted numbers on the fuse to indicate amperage. There
are no identifying marks on the fuse to tell who is making it. The fuses are known to be distributed
by Harbor Freight Tools but there may be other marketers, and packaging of this style of fuse. It
would be prudent to replace these fuses if found in a customers vehicle. Likewise, if wiring
overheating is found you should check the fuse panel for the presence of this style of fuse.
All GM dealers should use genuine GM fuses on the vehicles they service. You should also
encourage the use of GM fuses to your customers to assure they are getting the required electrical
system protection. GM has no knowledge of any concerns with other aftermarket fuses. If
additional information becomes available, this bulletin will be updated.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Locations >
I/P Fuse Block
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Locations >
I/P Fuse Block > Page 1759
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Application
and ID > Instrument Panel (I/P) Fuse Block Label
Fuse: Application and ID Instrument Panel (I/P) Fuse Block Label
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Application
and ID > Instrument Panel (I/P) Fuse Block Label > Page 1762
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Application
and ID > Instrument Panel (I/P) Fuse Block Label > Page 1763
Fuse: Application and ID Under Hood Electrical Center
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Application
and ID > Instrument Panel (I/P) Fuse Block Label > Page 1764
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse > Component Information > Application
and ID > Page 1765
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Locations > Auxiliary Fuse Block, Special Equipment Option (Seo)
Fuse Block: Locations Auxiliary Fuse Block, Special Equipment Option (Seo)
Under I/P
Behind LH I/P, Left Of Brake Pedal Bracket
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Locations > Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 1770
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Locations > Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 1771
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Locations > Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 1772
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label
Fuse Block: Application and ID Instrument Panel (I/P) Fuse Block Label
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 1775
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Fuse Block > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 1776
Fuse Block: Application and ID Under Hood Electrical Center
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Convenience Center <--> [Relay Box] >
Component Information > Locations > Convenience Center
Convenience Center: Locations Convenience Center
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Convenience Center <--> [Relay Box] >
Component Information > Locations > Convenience Center > Page 1781
Behind LH I/P, Left Of Brake Pedal Bracket
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Convenience Center <--> [Relay Box] >
Component Information > Locations > Convenience Center > Page 1782
Under I/P
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Convenience Center <--> [Relay Box] >
Component Information > Locations > Convenience Center > Page 1783
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Fuses and Circuit Breakers > Convenience Center <--> [Relay Box] >
Component Information > Locations > Page 1784
Convenience Center: Application and ID
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Coolant Level Indicator Lamp > Component
Information > Description and Operation
Coolant Level Indicator Lamp: Description and Operation
DESCRIPTION
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
OPERATION
Some vehicles use a buzzer or indicator lamp to convey a low coolant level condition. The buzzer
or lamp is activated by a sensor, located in the radiator, when the coolant level becomes one quart
low, or more.
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Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Coolant Level Indicator Lamp > Component
Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant Level Low
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator Off W/Coolant Level
Low
Fig. 97 Chart 6: Low Coolant Level Indicator Inoperative W/Coolant Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Coolant Level Indicator Lamp > Component
Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant Level Low > Page 1791
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator On w/Coolant Level
OK
Fig. 96 Chart 5: Low Coolant Level Indicator On W/Coolant Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Coolant Level Indicator Lamp > Component
Information > Testing and Inspection > Page 1792
Coolant Level Indicator Lamp: Service and Repair
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Malfunction Indicator Lamp > Component
Information > Diagrams > Diagram Information and Instructions
Malfunction Indicator Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information > Diagrams > Diagram Information and Instructions > Page 1799
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 1802
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 1803
Malfunction Indicator Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Information > Diagrams > Diagram Information and Instructions > Page 1804
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Oil Change Reminder Lamp > Component
Information > Service and Repair > Change Oil or Change Oil Now Message
Oil Change Reminder Lamp: Service and Repair Change Oil or Change Oil Now Message
1. Turn ignition switch to On position, without starting engine. 2. Press accelerator pedal to wide
open throttle (WOT) position and release three times within five seconds. 3. If Change Oil warning
indicator goes out, system has been reset. 4. If Change Oil warning indicator does not reset, turn
ignition switch Off and repeat procedure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Oil Change Reminder Lamp > Component
Information > Service and Repair > Change Oil or Change Oil Now Message > Page 1832
Oil Change Reminder Lamp: Service and Repair Engine Oil Life Monitor
ENGINE OIL LIFE MONITOR
The "CHANGE OIL" monitor light on the instrument cluster is a reminder to change oil. When
changing oil, reset the oil life monitor whether the "CHANGE OIL" light came on or not.
NOTE: Disconnecting the negative battery cable will not reset the oil life monitor.
Reset monitor as follows:
1. Turn ignition switch to "ON" position, but don't start engine. 2. Fully depress accelerator pedal to
Wide Open Throttle (WOT) position and release it three times within five seconds.
^ The light is controlled by the Powertrain Control Module (PCM). The PCM is monitoring the TPS
signal for 3 consecutive signals above
96%. The PCM will acknowledge, if the reset was successful, by flashing the "Change Oil" light
twice, then turning off the light.
3. If "CHANGE OIL" warning/indicator lamp flashes then goes out, the system has been reset. 4. If
"CHANGE OIL" warning/indicator lamp doesn't reset, turn ignition switch "OFF" and repeat
procedure.
^ If "CHANGE OIL" light is inoperative or remains "ON," refer to Powertrain Management /
Computerized Engine Controls / Testing
Procedures section. (DTC 95)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Oil Level Warning Indicator > Component
Information > Description and Operation
Oil Level Warning Indicator: Description and Operation
DESCRIPTION
This lamp illuminates to warn the driver that the engine oil level is low. When the ignition switch is
first moved to Run, the oil level indicator lights for about 1 1/2 seconds as a bulb check. The oil
level detection circuit has two internal timers. The first timer records the amount of time the ignition
has been Off. The second timer records the amount of time the ignition has been On before the
ignition was shut Off. The instrument cluster uses this information to determine if the engine has
been sitting long enough for the oil to have returned to the oil pan.
OPERATION
The oil level monitoring circuits will check the oil level switch under the following conditions:
1. Ignition has been turned Off for more than 30 minutes. 2. Ignition has been Off for at least three
minutes after ignition has been On for at least 12 minutes.
If the oil level is low (oil level switch open), the "Check Oil" indicator will be turned On for the
remainder of the ignition cycle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Oil Level Warning Indicator > Component
Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator Inoperative W/Oil Level Low
Fig. 99 Chart 8: Low Oil Level Indicator Inoperative W/Oil Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Service Reminder Indicators > Oil Level Warning Indicator > Component
Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low > Page 1838
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator On w/Oil Level OK
Fig. 98 Chart 7: Low Oil Level Indicator On W/Oil Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Vehicle Lifting > Component Information > Service and
Repair
Vehicle Lifting: Service and Repair
Vehicle Lift Points
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires
Tires: Technical Service Bulletins Wheels/Tires - Use of Nitrogen Gas in Tires
INFORMATION
Bulletin No.: 05-03-10-020C
Date: April 27, 2010
Subject: Use of Nitrogen Gas in Tires
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 05-03-10-020B (Section 03 - Suspension).
GM's Position on the Use of Nitrogen Gas in Tires
General Motors does not oppose the use of purified nitrogen as an inflation gas for tires. We expect
the theoretical benefits to be reduced in practical use due to the lack of an existing infrastructure to
continuously facilitate inflating tires with nearly pure nitrogen. Even occasional inflation with
compressed atmospheric air will negate many of the theoretical benefits. Given those theoretical
benefits, practical limitations, and the robust design of GM original equipment TPC tires, the
realized benefits to our customer of inflating their tires with purified nitrogen are expected to be
minimal.
The Promise of Nitrogen: Under Controlled Conditions
Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer
through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile
racing. The following benefits under controlled conditions are attributed to nitrogen gas and its
unique properties:
- A reduction in the expected loss of Tire Pressure over time.
- A reduction in the variance of Tire Pressures with temperature changes due to reduction of water
vapor concentration.
- A reduction of long term rubber degradation due to a decrease in oxygen concentrations.
Important These are obtainable performance improvements when relatively pure nitrogen gas is
used to inflate tires under controlled conditions.
The Promise of Nitrogen: Real World Use
Nitrogen inflation can provide some benefit by reducing gas migration (pressure loss) at the
molecular level through the tire structure. NHTSA (National Highway Traffic Safety Administration)
has stated that the inflation pressure loss of tires can be up to 5% a month. Nitrogen molecules are
larger than oxygen molecules and, therefore, are less prone to "seeping" through the tire casing.
The actual obtainable benefits of nitrogen vary, based on the physical construction and the
materials used in the manufacturing of the tire being inflated.
Another potential benefit of nitrogen is the reduced oxidation of tire components. Research has
demonstrated that oxygen consumed in the oxidation process of the tire primarily comes from the
inflation media. Therefore, it is reasonable to assume that oxidation of tire components can be
reduced if the tire is inflated with pure nitrogen. However, only very small amounts of oxygen are
required to begin the normal oxidation process. Even slight contamination of the tire inflation gas
with compressed atmospheric air during normal inflation pressure maintenance, may negate the
benefits of using nitrogen.
GM Tire Quality, Technology and Focus of Importance
Since 1972, General Motors has designed tires under the TPC (Tire Performance Criteria)
specification system, which includes specific requirements that ensure robust tire performance
under normal usage. General Motors works with tire suppliers to design and manufacture original
equipment tires for GM vehicles. The GM TPC addresses required performance with respect to
both inflation pressure retention, and endurance properties for original equipment tires. The
inflation pressure retention requirements address availability of oxygen and oxidation concerns,
while endurance requirements ensure the mechanical structure of the tire has sufficient strength.
This combination has provided our customers with tires that maintain their structural integrity
throughout their useful treadlife under normal operating conditions.
Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure
maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Maintaining the
correct inflation pressure allows the tire to perform as intended by the vehicle manufacturer in
many areas, including comfort, fuel economy, stopping distance, cornering, traction, treadwear,
and noise. Since the load carrying capability of a tire is related to inflation pressure, proper inflation
pressure maintenance is necessary for the tire to support the load imposed by the vehicle without
excessive structural
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1847
degradation.
Important Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure
maintenance of tires is critical for overall tire, and ultimately, vehicle performance.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1848
Tires: Technical Service Bulletins Tires/Wheels - Tire Puncture Repair Procedures
INFORMATION
Bulletin No.: 04-03-10-001F
Date: April 27, 2010
Subject: Tire Puncture Repair Procedures For All Cars and Light Duty Trucks
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2010 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 04-03-10-001E (Section 03 - Suspension).
This bulletin covers puncture repair procedures for passenger car and light duty truck radial tires in
the tread area only. The tire manufacturer must be contacted for its individual repair policy and
whether or not the speed rating is retained after repair.
Caution
- Tire changing can be dangerous and should be done by trained professionals using proper tools
and procedures. Always read and understand any manufacturer's warnings contained in their
customers literature or molded into the tire sidewall.
- Serious eye and ear injury may result from not wearing adequate eye and ear protection while
repairing tires.
- NEVER inflate beyond 275 kPa (40 pounds) pressure to seat beads.
Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may
require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be
used. Consult the tire manufacturer for its individual repair policy.
- NEVER stand, lean or reach over the assembly during inflation.
Repairable area on a radial tire.
Important
- NEVER repair tires worn to the tread indicators 1.59 mm (2/32") remaining depth).
- NEVER repair tires with a tread puncture larger than 6.35 mm (1/4").
- NEVER substitute an inner tube for a permissible or non-permissible repair.
- NEVER perform an outside-in tire repair (plug only, on the wheel).
- Every tire must be removed from the wheel for proper inspection and repair.
- Regardless of the type of repair used, the repair must seal the inner liner and fill the injury.
- Consult with repair material supplier/manufacturer for repair unit application procedures and
repair tools/repair material recommendations.
Three basic steps for tire puncture repair:
1. Remove the tire from the wheel for inspection and repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1849
2. Fill the injury (puncture) to keep moisture out. 3. Seal the inner liner with a repair unit to prevent
air loss.
External Inspection
1. Prior to demounting, inspect the tire surface, the valve and the wheel for the source of the leak
by using a water and soap solution. Mark the
injured area and totally deflate the tire by removing the valve core.
2. Demount the tire from the wheel and place the tire on a well-lighted spreader.
Internal Inspection
1. Spread the beads and mark the puncture with a tire crayon. 2. Inspect the inner tire for any signs
of internal damage. 3. Remove the puncturing object, noting the direction of the penetration. 4.
Probe the injury with a blunt awl in order to determine the extent and direction of the injury. 5.
Remove any loose foreign material from the injury. 6. Punctures exceeding 6.35 mm (1/4") should
not be repaired.
Cleaning
1. Clean the area around the puncture thoroughly with a proper liner cleaner, clean cloth and a
scraper. This step serves to remove dirt and mold
lubricants to insure proper adhesion and non-contamination of the buffing tool.
2. Refer to information on the product or manufacturer's Material Safety Data Sheet and follow
guidelines for handling and disposal.
Clean the Injury Channel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1850
1. Use a proper hand reamer, carbide cutter or drill bit to ream the puncture channel from the inside
of the tire in order to clean the injury. 2. Remove steel wires protruding above the liner surface to
prevent damage to the repair unit. 3. Consult your repair material supplier for recommended
reaming tool(s).
Fill the Injury
1. It is necessary to fill the injury channel to provide back up for the repair unit and to prevent
moisture from entering the tire fabric and steel wires. 2. (For combination repair/plug units skip this
step.) Cement the injured channel and fill the injury from the inside of the tire with the repair plug
per
repair material manufacturer's recommendations. Without stretching the plug, cut the plug off just
above the inside tire surface.
3. Consult your repair material supplier for proper repair material selection.
Repair Unit Selection
Important Do not install the repair unit in this step.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1851
1. Center the repair unit over the injury as a reference and outline an area larger than the unit so
that buffing will not remove the crayon marks. 2. Remove the repair unit. 3. DO NOT overlap
previous or multiple repair units. 4. Consult your repair material supplier for proper repair unit
selection.
Buffing
1. To prevent contamination and preserve the outline, buff within the marked area thoroughly and
evenly with a low speed buffing tool using a fine
wire brush or gritted rasp.
2. Buff to a smooth velvet surface (RMA #1 or #2 buffed texture). 3. Use caution not to gouge the
inner liner or expose casing fabric. 4. Remove any buffing dust with a vacuum cleaner. 5. Consult
your repair material supplier for a proper buffing tool.
Cementing
Apply chemical cement according to the repair material manufacturer's procedures.
Repair Unit Application
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1852
1. The tire must be in the relaxed position when the repair unit is installed (Do not spread the beads
excessively).
Two-Piece Plug and Repair Units
1. If applicable, install the repair unit so that the alignment is correct. 2. Center the repair unit over
the injury and stitch down thoroughly with the stitching tool, working from the center out.
3. Being careful not to stretch the plug material, cut the plug flush with the outer tread.
Combination Repair/Plug Units
1. Pull the plug through the injury until the repair just reaches the liner. Stitch down thoroughly. 2.
Follow the repair material manufacturer's recommendations for further installation instructions.
2. Consult your repair material supplier for the proper stitching tool.
Safety Cage
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1853
Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may
require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be
used. Consult the tire manufacturer for its individual repair policy.
Final Inspection
1. After remounting and inflating the tire, check both beads, the repair and the valve with a water
and soap solution in order to detect leaks. 2. If the tire continues to lose air, the tire must be
demounted and reinspected. 3. Balance the tire and wheel assembly. Refer to Tire and Wheel
Assembly Balancing - OFF Vehicle.
For additional tire puncture repair information, contact:
Rubber Manufacturers Association (RMA)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1854
Tires: Technical Service Bulletins Tires - Correct Inflation Pressure Information
INFORMATION
Bulletin No.: 00-00-90-002J
Date: January 28, 2009
Subject: Information on Proper Tire Pressure
Models: 2010 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2009 and
Prior HUMMER H2, H3, H3T 2005-2009 Saab 9-7X
Supercede:
This bulletin is being revised to add model years and clarify additional information. Please discard
Corporate Bulletin Number 00-00-90-002I (Section 00 - General Information).
Important:
^ Adjustment of tire pressure for a customer with a Low Tire Pressure Monitor (TPM) light on and
no codes in the TPM system is NOT a warrantable repair. Claims to simply adjust the tire pressure
will be rejected.
^ ALL tires (including the spare tire) MUST be set to the recommended inflation pressure stated on
the vehicle's tire placard (on driver's door) during the PRE-DELIVERY INSPECTION (PDI).
Recommended inflation pressure is not the pressure printed on tire sidewall.
^ Tires may be over-inflated from the assembly plant due to the mounting process.
^ Generally a 5.6°C (10°F) temperature change will result in (is equivalent to) a 6.9 kPa (1 psi) tire
pressure change.
^ 2008-2009 HUMMER H2 Only - The H2 comes standard with Light Truck "D" Load Range tires
with a recommended cold inflation pressure of 289 kPa (42 psi). These tires will alert the driver to a
low pressure situation at roughly 262 kPa (38 psi) due to a requirement in FMVSS 138 which
specifies a Minimum Activation Pressure for each tire type. This creates a relatively narrow window
of "usable" pressure values and the warning will be more sensitive to outside temperature changes
during the colder months. As with other cold temperature/tire pressure issues, there is nothing
wrong with the system itself. If a vehicle is brought in with this concern, check for tire damage and
set all tires to the Recommended Cold Inflation Pressure shown on the vehicle placard.
Accurate tire pressures ensure the safe handling and appropriate ride characteristics of GM cars
and trucks. It is critical that the tire pressure be adjusted to the specifications on the vehicle¡C■s
tire placard during PDI.
Ride, handling and road noise concerns may be caused by improperly adjusted tire pressure.
The first step in the diagnosis of these concerns is to verify that the tires are inflated to the correct
pressures. The recommended tire inflation pressure is listed on the vehicle¡C■s tire placard. The
tire placard is located on the driver¡C■s side front or rear door edge, center pillar, or the rear
compartment lid.
Tip
^ Generally a 5.6°C (10°F) temperature increase will result in (is equivalent to) a 6.9 kPa (1 psi) tire
pressure increase.
^ The definition of a "cold" tire is one that has been sitting for at least 3 hours, or driven no more
than 1.6 km (1 mi).
^ On extremely cold days, if the vehicle has been indoors, it may be necessary to compensate for
the low external temperature by adding additional air to the tire during PDI.
^ During cold weather, the Tire Pressure Monitor (TPM) indicator light (a yellow horseshoe with an
exclamation point) may illuminate. If this indicator turns off after the tires warm up (reach operating
temperature), the tire pressure should be reset to placard pressure at the cold temperature.
^ The TPM system will work correctly with nitrogen in tires.
^ The TPM system is compatible with the GM Vehicle Care Tire Sealant but may not be with other
commercially available sealants.
Important:
^ Do not use the tire pressure indicated on the tire itself as a guide.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 1855
^ Always inspect and adjust the pressure when the tires are cold.
^ Vehicles that have different pressures for the front and the rear need to be adjusted after tire
rotation.
Improper tire inflation may result in any or all of the following conditions:
^ Premature tire wear
^ Harsh ride
^ Excessive road noise
^ Poor handling
^ Reduced fuel economy
^ Low Tire Pressure Monitor (TPM) Light ON
^ Low Tire Pressure Message on the Drivers Information Center (DIC)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Tires > Component Information > Technical Service
Bulletins > Page 1856
Tires: Specifications
Front ....................................................................................................................................................
......................................................... 210 kPa (30 psi) Rear ................................................................
.............................................................................................................................................. 210 kPa
(30 psi) Full-Size Spare .......................................................................................................................
...................................................................... 240 kPa (35 psi)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation (RFV)
Wheels: Customer Interest Wheels/Tires - Tire Radial Force Variation (RFV)
INFORMATION
Bulletin No.: 00-03-10-006F
Date: May 04, 2010
Subject: Information on Tire Radial Force Variation (RFV)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3 2009
and Prior Saab 9-7X 2000-2005 Saturn L Series 2003-2007 Saturn ION
Supercede: This bulletin is being revised to considerably expand the available information on
Radial Force Variation (RFV) and should be reviewed in whole. Please discard Corporate Bulletin
Number 00-03-10-006E (Section 03 - Suspension).
Important
- Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven
a minimum of 16 km (10 mi) to ensure removal of any flat-spotting. Refer to Corporate Bulletin
Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original Equipment Tires.
- Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel
assemblies for each vehicle.
The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation
measurement equipment, such as the Hunter GSP9700. This type of equipment can be a valuable
tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force
variation is highway speed shake on smooth roads.
Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out
of round and tire force variation. These three conditions are not necessarily related. All three
conditions must be addressed.
Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle,
two plane dynamic wheel balancers are readily available and can accurately correct any
imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer,
and proper balance weights, are all factors required for a quality balance. However, a perfectly
balanced tire/wheel assembly can still be "oval shaped" and cause a vibration.
Before balancing, perform the following procedures.
Tire and Wheel Diagnosis
1. Set the tire pressure to the placard values. 2. With the vehicle raised, ensure the wheels are
centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while
shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick.
3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and
correct as necessary:
- Missing balance weights
- Bent rim flange
- Irregular tire wear
- Incomplete bead seating
- Tire irregularities (including pressure settings)
- Mud/ice build-up in wheel
- Stones in the tire tread
- Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to
diagnosing a smooth road shake condition.
4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a
sufficient distance on a known, smooth road
surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes
are applied lightly and the pulsation felt in the steering wheel increases, refer to the Brakes section
of the service manual that deals with brake-induced pulsation. If you can start to hear the vibration
as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order
(one pulse per propshaft revolution) driveline vibration. Driveline first order vibrations are high
enough in frequency that most humans can start to hear them at highway speeds, but are too high
to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment.
If the vehicle exhibits this low boom and the booming pulses in-and-out on a regular basis (like a
throbbing), chances are good that the vehicle could have driveline vibration. This type
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation (RFV) > Page 1865
of vibration is normally felt more in the "seat of the pants" than the steering wheel.
5. Next, record the Hertz (Hz) reading as displayed by the EVA onto the tire data worksheet found
at the end of this bulletin. This should be done
after a tire break-in period of at least 16 km (10 mi) at 72 km/h (45 mph) or greater, in order to
eliminate any possible tire flat-spotting. This reading confirms what the vehicle vibration frequency
is prior to vehicle service and documents the amount of improvement occurring as the result of the
various steps taken to repair. Completing the Steering Wheel Shake Worksheet below is required.
A copy of the completed worksheet must be saved with the R.O. and a copy included with any
parts returned to the Warranty Parts Center for analysis. A reading of 35 to 50 Hz typically
indicates a first order propshaft vibration. If this is the situation, refer to Corporate Bulletin Number
08-07-30-044D. Generally, a reading between 10 and 20 Hz indicates a tire/wheel vibration and if
this is the reading obtained, continue using this bulletin. If the tire 1st order vibration goes away
and stays away during this evaluation, the cause is likely tire flat-spotting. Tire flat-spotting vibration
may come and go at any speed over 72 km/h (45 mph) during the first 10 minutes of operation, if
vibration continues after 10 minutes of driving at speeds greater than 72 km/h (45 mph), tire
flat-spotting can be ruled out as the cause for vibration.
6. If flat-spotting is the cause, provide the explanation that this has occurred due to the vehicle
being parked for long periods of time and that the
nature of the tire is to take a set. Refer to Corporate Bulletin Number 03-03-10-007E: Information
on Tire/Wheel Characteristics (Vibration, Balance, Shake, Flat Spotting) of GM Original Equipment
Tires.
7. If the road test indicates a shake/vibration exists, check the imbalance of each tire/wheel
assembly on a known, calibrated, off-car dynamic
balancer.Make sure the mounting surface of the wheel and the surface of the balancer are
absolutely clean and free of debris. Be sure to chose the proper cone/collet for the wheel, and
always use the pilot bore for centering. Never center the wheel using the hub-cap bore since it is
not a precision machined surface. If any assembly calls for more than 1/4 ounce on either rim
flange, remove all balance weights and rebalance to as close to zero as possible. If you can see
the vibration (along with feeling it) in the steering wheel (driving straight without your hands on the
wheel), it is very likely to be a tire/wheel first order (one pulse per revolution) disturbance. First
order disturbances can be caused by imbalance as well as non-uniformities in tires, wheels or
hubs. This first order frequency is too low for a human to hear, but if the amplitude is high enough,
it can be seen.
If a vibration or shake still exists after balancing, any out of round conditions, of the wheel, and
force variation conditions of the tire, must be addressed. Equipment such as the Hunter GSP9700
can address both (it is also a wheel balancer).
Tire radial force vibration (RFV) can be defined as the amount of stiffness variation the tire will
produce in one revolution under a constant load. Radial force variation is what the vehicle feels
because the load (weight) of the vehicle is always on the tires. Although free runout of tires (not
under load) is not always a good indicator of a smooth ride, it is critical that total tire/wheel
assembly runout be within specification.
Equipment such as the Hunter GSP9700 loads the tire, similar to on the vehicle, and measures
radial force variation of the tire/wheel assembly. Note that the wheel is affecting the tire's RFV
measurement at this point. To isolate the wheel, its runout must be measured. This can be easily
done on the Hunter, without the need to set up dial indicators. If the wheel meets the runout
specification, the tire's RFV can then be addressed.
After measuring the tire/wheel assembly under load, and the wheel alone, the machine then
calculates (predicts) the radial force variation of the tire. However, because this is a prediction that
can include mounting inaccuracies, and the load wheel is much smaller in diameter than used in
tire production, this type of service equipment should NOT be used to audit new tires. Rather, it
should be used as a service diagnostic tool to minimize radial force variation of the tire/wheel
assembly.
Equipment such as the Hunter GSP9700 does an excellent job of measuring wheel runout, and of
finding the low point of the wheel (for runout) and the high point of the tire (for radial force
variation). This allows the tire to be matched mounted to the wheel for lowest tire/wheel assembly
force variation.
The machine will simplify this process into easy steps. The following assembly radial force variation
numbers should be used as a guide:
When measuring RFV and match mounting tires perform the following steps.
Measuring Wheel Runout and Assembly Radial Force Variation
Important The completed worksheet at the end of this bulletin must be attached to the hard copy of
the repair order.
- Measure radial force variation and radial runout.
- If a road force/balancing machine is used, record the radial force variation (RFV) on the
worksheet at the end of this bulletin. It may be of benefit to have the lowest RFV assembly to the
front left corner. If the machine is not available and the EVA data suggests there is an issue, swap
the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem
still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those
tires onto the subject vehicle.
- If a runout/balancing machine is used, record the radial runout of the tire/wheel assemblies on the
worksheet at the end of this bulletin. If one or more of the tire/wheel assemblies are more than.040
in (1.02 mm), match mount the tire to the wheel to get below.040 in (1.02 mm). For sensitive
customers, readings of 0.030 inch (0.76 mm) or less are preferable, it may also be of benefit to
have the lowest runout assembly to the front left corner. If the machine is not available and the
EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the
back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do
not exhibit the same frequency and swap those tires
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation (RFV) > Page 1866
onto the subject vehicle.
- After match mounting, the tire/wheel assembly must be rebalanced.
If match mounting tires to in-spec wheels produces assembly values higher than these, tire
replacement may be necessary. Replacing tires at lower values will probably mean good tires are
being condemned. Because tires can sometimes become temporarily flat-spotted, which will affect
force variation, it is important that the vehicle be driven at least 16 km (10 mi) prior to measuring.
Tire pressure must also be adjusted to the usage pressure on the vehicle's tire placard prior to
measuring.
Most GM vehicles will tolerate radial force variation up to these levels. However, some vehicles are
more sensitive, and may require lower levels. Also, there are other tire parameters that equipment
such as the Hunter GSP9700 cannot measure that may be a factor. In such cases, TAC should be
contacted for further instructions.
Important
- When mounting a GM wheel to a wheel balancer/force variation machine, always use the wheel's
center pilot hole. This is the primary centering mechanism on all GM wheels; the bolt holes are
secondary. Usually a back cone method to the machine should be used. For added accuracy and
repeatability, a flange plate should be used to clamp the wheel onto the cone and machine. This
system is offered by all balancer manufacturers in GM's dealer program.
- Any type of service equipment that removes tread rubber by grinding, buffing or truing is NOT
recommended, and may void the tire warranty. However, tires may have been ground by the tire
company as part of their tire manufacturing process. This is a legitimate procedure.
Steering Wheel Shake Worksheet
When diagnosing vibration concerns, use the following worksheet in conjunction with the
appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation (RFV) > Page 1867
Refer to the appropriate section of SI for specifications and repair procedures that are related to the
vibration concern.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > Customer Interest: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels
Wheels: Customer Interest Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels
TECHNICAL
Bulletin No.: 05-03-10-003F
Date: April 27, 2010
Subject: Low Tire Pressure, Leaking Cast Aluminum Wheels (Repair with Adhesive Sealant)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2010 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X with Cast Aluminum Wheels
Supercede: This bulletin is being revised to update the model years and the bulletin reference
information. Please discard Corporate Bulletin Number 05-03-10-003E (Section 03 - Suspension).
Condition
Some customers may comment on a low tire pressure condition.
Diagnosis of the low tire pressure condition indicates an air leak through the cast aluminum wheel.
Cause
Porosity in the cast aluminum wheel may be the cause.
Notice
This bulletin specifically addresses issues related to the wheel casting that may result in an air
leak. For issues related to corrosion of the wheel in service, please refer to Corporate Bulletin
Number 08-03-10-006C - Tire Slowly Goes Flat, Tire Air Loss, Low Tire Pressure Warning Light
Illuminated, Aluminum Wheel Bead Seat Corrosion (Clean and Resurface Wheel Bead Seat).
Correction
1. Remove the tire and wheel assembly from the vehicle. Refer to the appropriate service
procedure in SI. 2. Locate the leaking area by inflating the tire to 276 kPa (40 psi) and dipping the
tire/wheel assembly in a water bath, or use a spray bottle with soap
and water to locate the specific leak location.
Important
- If the porosity leak is located in the bead area of the aluminum rim (where the tire meets the rim),
the wheel should be replaced.
- If two or more leaks are located on one wheel, the wheel should be replaced.
3. If air bubbles are observed, mark the location.
- If the leak location is on the tire/rubber area, refer to Corporate Bulletin Number 04-03-10-001F Tire Puncture Repair Procedures for All Cars and Light Duty Trucks.
- If the leak is located on the aluminum wheel area, continue with the next step.
4. Inscribe a mark on the tire at the valve stem in order to indicate the orientation of the tire to the
wheel. 5. Dismount the tire from the wheel. Refer to Tire Mounting and Dismounting. 6. Remove
the tire pressure sensor. Refer to Tire Pressure Sensor removal procedure in SI. 7. Scuff the
INSIDE rim surface at the leak area with #80 grit paper and clean the area with general purpose
cleaner, such as 3M(R) General Purpose
Adhesive Cleaner, P/N 08984, or equivalent.
8. Apply a 3 mm (0.12 in) thick layer of Silicone - Adhesive/Sealant, P/N 12378478 (in Canada, use
88900041), or equivalent, to the leak area. 9. Allow for the adhesive/sealant to dry.
Notice Caution must be used when mounting the tire so as not to damage the sealer. Damaging
the repair area may result in an air leak.
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > Customer Interest: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels >
Page 1872
10. Align the inscribed mark on the tire with the valve stem on the wheel. 11. Reinstall the Tire
Pressure Sensor. Refer to Tire Pressure Sensor installation procedure in SI. 12. Mount the tire on
the wheel. Refer to Tire Mounting and Dismounting. 13. Pressurize the tire to 276 kPa (40 psi) and
inspect for leaks. 14. Adjust tire pressure to meet the placard specification. 15. Balance the
tire/wheel assembly. Refer to Tire and Wheel Assembly Balancing - Off-Vehicle. 16. Install the tire
and wheel assembly onto the vehicle. Refer to the appropriate service procedure in SI.
Parts Information
Warranty Information (excluding Saab U.S. Models)
Important The Silicone - Adhesive/Sealant comes in a case quantity of six. ONLY charge warranty
one tube of adhesive/sealant per wheel repair.
For vehicles repaired under warranty, use:
One leak repair per wheel.
Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use the table above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Staining/Pitting/Corrosion
INFORMATION
Bulletin No.: 00-03-10-002F
Date: April 21, 2011
Subject: Chemical Staining, Pitting, Corrosion and/or Spotted Appearance of Chromed Aluminum
Wheels
Models:
2012 and Prior GM Cars and Trucks
Supercede: This bulletin is being revised to update model years, suggest additional restorative
products and add additional corrosion information. Please discard Corporate Bulletin Number
00-03-10-002E (Section 03 - Suspension). Important You may give a copy of this bulletin to the
customer.
What is Chemical Staining of Chrome Wheels? Figure 1
Chemical staining in most cases results from acid based cleaners (refer to Figure 1 for an
example). These stains are frequently milky, black, or greenish in appearance. They result from
using cleaning solutions that contain acids on chrome wheels. Soap and water is usually sufficient
to clean wheels.
If the customer insists on using a wheel cleaner they should only use one that specifically states
that it is safe for chromed wheels and does not contain anything in the following list. (Dealers
should also survey any products they use during prep or normal cleaning of stock units for these
chemicals.)
- Ammonium Bifluoride (fluoride source for dissolution of chrome)
- Hydrofluoric Acid (directly dissolves chrome)
- Hydrochloric Acid (directly dissolves chrome)
- Sodium Dodecylbenzenesulfonic Acid
- Sulfamic Acid
- Phosphoric Acid
- Hydroxyacetic Acid
Notice
Many wheel cleaner instructions advise to take care to avoid contact with painted surfaces. Most
customers think of painted surfaces as the fenders, quarter panels and other exterior sheet metal.
Many vehicles have painted brake calipers. Acidic wheel cleaners may craze, crack, or discolor the
paint on the brake calipers. Damage from wheel cleaners is not covered under the vehicle new car
warranty. Soap and water applied with a soft brush is usually all that is required to clean the
calipers.
Whenever any wheel cleaner is used, it must be THOROUGHLY rinsed off of the wheel with clean,
clear water. Special care must be taken to rinse under the hub cap, balance weights, wheel nuts,
lug nut caps, between the wheel cladding and off the back side of the wheel. Wheels returned to
the Warranty Parts Center (WPC) that exhibit damage from wheel cleaners most often have the
damage around and under the wheel weight where the cleaner was incompletely flushed away.
Notice
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 1878
Do not use cleaning solutions that contain hydrofluoric, oxalic and most other acids on chrome
wheels (or any wheels).
If the customer is unsure of the chemical make-up of a particular wheel cleaner, it should be
avoided.
For wheels showing signs of milky staining from acidic cleaners, refer to Customer Assistance and
Instructions below.
Warranty of Stained Chrome Wheels
Stained wheels are not warrantable. Most acid based cleaners will permanently stain chrome
wheels. Follow-up with dealers has confirmed that such cleaners were used on wheels that were
returned to the Warranty Parts Center (WPC). Any stained wheels received by the WPC will be
charged back to the dealership. To assist the customer, refer to Customer Assistance and
Instructions below.
Pitting or Spotted Appearance of Chrome Wheels Figure 2
A second type or staining or finish disturbance may result from road chemicals, such as calcium
chloride used for dust control of unpaved roads. The staining will look like small pitting (refer to
Figure 2). This staining will usually be on the leading edges of each wheel spoke, but may be
uniformly distributed. If a vehicle must be operated under such conditions, the chrome wheels
should be washed with mild soap and water and thoroughly rinsed as soon as conveniently
possible.
Important Road chemicals, such as calcium chloride used for dust control of unpaved roads, can
also stain chrome wheels. The staining will look like small pitting. This staining will usually be on
the leading edges of each wheel spoke. This is explained by the vehicle traveling in the forward
direction while being splashed by the road chemical. If a vehicle must be operated under such
conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed
as soon as conveniently possible.
Warranty of Pitted or Spotted Chrome Wheels
Wheels returned with pitting or spotting as a result of road chemicals may be replaced one time.
Damage resulting from contact with these applied road chemicals is corrosive to the wheels finish
and may cause damage if the wheels are not kept clean.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean if they are operating the vehicle in an area that
applies calcium chloride or other dust controlling chemicals! "GM of Canada" dealers require prior
approval by the District Manager - Customer Care and Service Process (DM-CCSP).
"Stardust" Corrosion of Chrome Wheels Figure 3
A third type of finish disturbance results from prolonged exposure to brake dust and resultant
penetration of brake dust through the chrome. As brakes are applied hot particles of brake material
are thrown off and tend to be forced through the leading edge of the wheel spoke windows by
airflow. These
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 1879
hot particles embed themselves in the chrome layer and create a small pit. If the material is allowed
to sit on the wheel while it is exposed to moisture or salt, it will corrode the wheel beneath the
chrome leaving a pit or small blister in the chrome.
Heavy brake dust build-up should be removed from wheels by using GM Chrome Cleaner and
Polish, P/N 1050173 (in Canada use 10953013). For moderate cleaning, light brake dust build-up
or water spots use GM Swirl Remover Polish, P/N 12377965 (in Canada, use Meguiars
Plast-X(TM) Clear Plastic Cleaner and Polish #G12310C**). After cleaning, the wheel should be
waxed using GM Cleaner Wax, P/N 12377966 (in Canada, use Meguiars Cleaner Wax
#M0616C**), which will help protect the wheel from brake dust and reduce adhesion of any brake
dust that gets on the wheel surface. For general maintenance cleaning, PEEK Metal Polish† may
be used. It will clean and shine the chrome and leave behind a wax coating that may help protect
the finish.
Warranty of Stardust Corroded Chrome Wheels
Wheels returned with pitting or spotting as a result of neglect and brake dust build-up may be
replaced one time.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean and free of prolonged exposure to brake dust
build-up. "GM of Canada" dealers require prior approval by the District Manager - Customer Care
and Service Process (DM-CCSP).
Customer Assistance and Instructions
GM has looked for ways customers may improve the appearance of wheels damaged by acidic
cleaners. The following product and procedure has been found to dramatically improve the
appearance of stained wheels. For wheels that have milky stains caused by acidic cleaners try the
following:
Notice
THE 3M CHROME AND METAL POLISH REQUIRED FOR THIS PROCEDURE IS AN
EXTREMELY AGGRESSIVE POLISH/CLEANER. THE WHEELS MUST BE CLEANED BEFORE
APPLICATION TO AVOID SCRATCHING THE WHEEL SURFACE. THIS PRODUCT WILL
REDUCE THE THICKNESS OF THE CHROME PLATING ON THE WHEEL AND IF USED
INCORRECTLY OR EXCESSIVELY MAY REMOVE THE CHROME PLATING ALL TOGETHER,
EXPOSING A LESS BRIGHT AND BRASSY COLORED SUB-LAYER. FOLLOW INSTRUCTIONS
EXACTLY.
1. Wash the wheels with vigorously with soap and water. This step will clean and may reduce
wheel staining. Flood all areas of the wheel with water
to rinse.
2. Dry the wheels completely.
Notice Begin with a small section of the wheel and with light pressure buff off polish and examine
results. ONLY apply and rub with sufficient force and time to remove enough staining that you are
satisfied with the results. Some wheels may be stained to the extent that you may only achieve a
50% improvement while others may be able to be restored to the original lustre. IN ALL CASES,
only apply until the results are satisfactory.
3. Apply 3M Chrome and Metal Polish #39527* with a clean terry cloth towel. As you apply the
polish, the staining will be diminished. 4. When dry, buff off the polish with a clean portion of the
towel. 5. Repeat application of the 3M Chrome and Metal Polish until satisfied with the results. If
continued applications fail to improve the appearance
further discontinue use.
This procedure will improve the appearance of the wheels and may, with repeated applications,
restore the finish dramatically. For wheels that exhibit spotting from road chemicals the above
procedure may marginally improve the condition but will not restore the finish or remove the pitting.
In this type of staining the wheel finish has actually been removed in spots and no manner of
cleaning will restore the finish.
†*We believe this source and their products to be reliable. There may be additional manufacturers
of such products/materials. General Motors does not endorse, indicate any preference for or
assume any responsibility for the products or material from this firm or for any such items that may
be available from other sources.
Parts Information
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 1880
*This product is currently available from 3M. To obtain information for your local retail location
please call 3M at 1-888-364-3577.
**This product is currently available from Meguiars (Canada). To obtain information for your local
retail location please call Meguiars at 1-800-347-5700 or at www.meguiarscanada.com.
^ This product is currently available from Tri-Peek International. To obtain information for your local
retail location please call Tri-Peek at
1-877-615-4272 or at www.tripeek.com.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires - Refinishing Aluminum
Wheels
Wheels: All Technical Service Bulletins Wheels/Tires - Refinishing Aluminum Wheels
INFORMATION
Bulletin No.: 99-08-51-007E
Date: March 17, 2011
Subject: Refinishing Aluminum Wheels
Models:
2012 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add additional model years. Please discard Corporate
Bulletin Number 99-08-51-007D (Section 08 - Body and Accessories).
This bulletin updates General Motor's position on refinishing aluminum wheels. GM does not
endorse any repairs that involve welding, bending, straightening or re-machining. Only cosmetic
refinishing of the wheel's coatings, using recommended procedures, is allowed.
Evaluating Damage
In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion,
scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be
sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the
wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been
refinished by an outside company must be returned to the same vehicle. The Dealer must record
the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to
Refinisher's Responsibility - Outside Company later in this bulletin.
Aluminum Wheel Refinishing Recommendations
- Chrome-plated aluminum wheels Re-plating these wheels is not recommended.
- Polished aluminum wheels These wheels have a polyester or acrylic clearcoat on them. If the
clearcoat is damaged, refinishing is possible. However, the required refinishing process cannot be
performed in the dealer environment. Refer to Refinisher's Responsibility - Outside Company later
in this bulletin.
- Painted aluminum wheels These wheels are painted using a primer, color coat, and clearcoat
procedure. If the paint is damaged, refinishing is possible. As with polished wheels, all original
coatings must be removed first. Media blasting is recommended. Refer to GM Aluminum
Refinishing Bulletin #53-17-03A for the re-painting of this type of wheel.
- Bright, machined aluminum wheels These wheels have a polyester or acrylic clearcoat on them.
In some cases, the recessed "pocket" areas of the wheel may be painted. Surface refinishing is
possible. The wheel must be totally stripped by media blasting or other suitable means. The wheel
should be resurfaced by using a sanding process rather than a machining process. This allows the
least amount of material to be removed.
Important Do not use any re-machining process that removes aluminum. This could affect the
dimensions and function of the wheel.
Painting is an option to re-clearcoating polished and bright machined aluminum wheels. Paint will
better mask any surface imperfections and is somewhat more durable than clearcoat alone. GM
recommends using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle
SILVER WA9967 for a very bright look. As an option, the body color may also be used. When using
any of the painting options, it is recommended that all four wheels be refinished in order to maintain
color uniformity. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for specific procedures
and product recommendations.
Refinisher's Responsibility - Outside Company
Important Some outside companies are offering wheel refinishing services. Such refinished wheels
will be permanently marked by the refinisher and are warranted by the refinisher. Any process that
re-machines or otherwise re-manufactures the wheel should not be used.
A refinisher's responsibility includes inspecting for cracks using the Zyglo system or the equivalent.
Any cracked wheels must not be refinished. No welding, hammering or reforming of any kind is
allowed. The wheel ID must be recorded and follow the wheel throughout the process in order to
assure that the same wheel is returned. A plastic media blast may be used for clean up of the
wheel. Hand and/or lathe sanding of the machined surface and the wheel window is allowed.
Material removal, though, must be kept to a minimum. Re-machining of the wheel is not allowed.
Paint and/or clear coat must not be present on the following surfaces: the nut chamfers, the wheel
mounting surfaces and the wheel pilot hole. The refinisher must permanently ID stamp the wheel
and warrant the painted/clearcoated surfaces for a minimum of one year or the remainder of the
new vehicle warranty, whichever is
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires - Refinishing Aluminum
Wheels > Page 1885
longer.
Important Whenever a wheel is refinished, the mounting surface and the wheel nut contact
surfaces must not be painted or clearcoated. Coating these surfaces could affect the wheel nut
torque.
When re-mounting a tire on an aluminum wheel, coated balance weights must be used in order to
reduce the chance of future cosmetic damage.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions
Wheels: All Technical Service Bulletins Wheels - Changing Procedures/Precautions
INFORMATION
Bulletin No.: 06-03-10-010A
Date: June 09, 2010
Subject: Information on Proper Wheel Changing Procedures and Cautions
Models:
2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER Models 2005-2009 Saab
9-7X 2005-2009 Saturn Vehicles
Attention:
Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel
Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and
reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel
installation. Always refer to SI for wheel lug nut torque specifications and complete jacking
instructions for safe wheel changing.
Supercede: This bulletin is being revised to include the 2011 model year and update the available
special tool list. Please discard Corporate Bulletin Number 06-03-10-010 (Section 03 Suspension).
Frequency of Wheel Changes - Marketplace Driven
Just a few years ago, the increasing longevity of tires along with greater resistance to punctures
had greatly reduced the number of times wheels were removed to basically required tire rotation
intervals. Today with the booming business in accessory wheels/special application tires (such as
winter tires), consumers are having tire/wheel assemblies removed - replaced - or installed more
than ever. With this increased activity, it opens up more of a chance for error on the part of the
technician. This bulletin will review a few of the common concerns and mistakes to make yourself
aware of.
Proper Servicing Starts With the Right Tools
The following tools have been made available to assist in proper wheel and tire removal and
installation.
- J 41013 Rotor Resurfacing Kit (or equivalent)
- J 42450-A Wheel Hub Resurfacing Kit (or equivalent)
Corroded Surfaces
One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle.
Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened
wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed
away from water splash. This action may result in clearance at the mating surface of the wheel and
an under-torqued condition.
Caution
Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or
brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting
surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is
moving, possibly resulting in a loss of control or personal injury.
Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If
corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding
pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating
surface.
The J 41013 (or equivalent) can be used to clean the following surfaces:
- The hub mounting surface
- The brake rotor mounting surface
- The wheel mounting surface
Use the J 42450-A (or equivalent) to clean around the base of the studs and the hub.
Lubricants, Grease and Fluids
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 1890
Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in
removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to
installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper
readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY.
Notice
Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or
drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to
clean, dry wheel studs and surfaces ONLY. Beginning with 2011 model year vehicles, put a light
coating of grease, GM P/N 1051344 (in Canada, P/N 9930370), on the inner surface of the wheel
pilot hole to prevent wheel seizure to the axle or bearing hub.
Wheel Stud and Lug Nut Damage
Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse.
You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not
retain properly, yet give the impression of fully tightening. Always inspect and replace any
component suspected of damage.
Tip
Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged
BEFORE tightening the nut.
Important If the vehicle has directional tread tires, verify the directional arrow on the outboard side
of the tire is pointing in the direction of forward rotation.
Wheel Nut Tightening and Torque
Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid
additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown
for each vehicle in SI. Always observe the proper wheel nut tightening sequence as shown below in
order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off
center resulting in vibration.
The Most Important Service You Provide
While the above information is well known, and wheel removal so common, technicians run the risk
of becoming complacent on this very important
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 1891
service operation. A simple distraction or time constraint that rushes the job may result in personal
injury if the greatest of care is not exercised. Make it a habit to double check your work and to
always side with caution when installing wheels.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force
Variation (RFV)
Wheels: All Technical Service Bulletins Wheels/Tires - Tire Radial Force Variation (RFV)
INFORMATION
Bulletin No.: 00-03-10-006F
Date: May 04, 2010
Subject: Information on Tire Radial Force Variation (RFV)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3 2009
and Prior Saab 9-7X 2000-2005 Saturn L Series 2003-2007 Saturn ION
Supercede: This bulletin is being revised to considerably expand the available information on
Radial Force Variation (RFV) and should be reviewed in whole. Please discard Corporate Bulletin
Number 00-03-10-006E (Section 03 - Suspension).
Important
- Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven
a minimum of 16 km (10 mi) to ensure removal of any flat-spotting. Refer to Corporate Bulletin
Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original Equipment Tires.
- Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel
assemblies for each vehicle.
The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation
measurement equipment, such as the Hunter GSP9700. This type of equipment can be a valuable
tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force
variation is highway speed shake on smooth roads.
Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out
of round and tire force variation. These three conditions are not necessarily related. All three
conditions must be addressed.
Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle,
two plane dynamic wheel balancers are readily available and can accurately correct any
imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer,
and proper balance weights, are all factors required for a quality balance. However, a perfectly
balanced tire/wheel assembly can still be "oval shaped" and cause a vibration.
Before balancing, perform the following procedures.
Tire and Wheel Diagnosis
1. Set the tire pressure to the placard values. 2. With the vehicle raised, ensure the wheels are
centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while
shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick.
3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and
correct as necessary:
- Missing balance weights
- Bent rim flange
- Irregular tire wear
- Incomplete bead seating
- Tire irregularities (including pressure settings)
- Mud/ice build-up in wheel
- Stones in the tire tread
- Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to
diagnosing a smooth road shake condition.
4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a
sufficient distance on a known, smooth road
surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes
are applied lightly and the pulsation felt in the steering wheel increases, refer to the Brakes section
of the service manual that deals with brake-induced pulsation. If you can start to hear the vibration
as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order
(one pulse per propshaft revolution) driveline vibration. Driveline first order vibrations are high
enough in frequency that most humans can start to hear them at highway speeds, but are too high
to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment.
If the vehicle exhibits this low boom and the booming pulses in-and-out on a regular basis (like a
throbbing), chances are good that the vehicle could have driveline vibration. This type
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force
Variation (RFV) > Page 1896
of vibration is normally felt more in the "seat of the pants" than the steering wheel.
5. Next, record the Hertz (Hz) reading as displayed by the EVA onto the tire data worksheet found
at the end of this bulletin. This should be done
after a tire break-in period of at least 16 km (10 mi) at 72 km/h (45 mph) or greater, in order to
eliminate any possible tire flat-spotting. This reading confirms what the vehicle vibration frequency
is prior to vehicle service and documents the amount of improvement occurring as the result of the
various steps taken to repair. Completing the Steering Wheel Shake Worksheet below is required.
A copy of the completed worksheet must be saved with the R.O. and a copy included with any
parts returned to the Warranty Parts Center for analysis. A reading of 35 to 50 Hz typically
indicates a first order propshaft vibration. If this is the situation, refer to Corporate Bulletin Number
08-07-30-044D. Generally, a reading between 10 and 20 Hz indicates a tire/wheel vibration and if
this is the reading obtained, continue using this bulletin. If the tire 1st order vibration goes away
and stays away during this evaluation, the cause is likely tire flat-spotting. Tire flat-spotting vibration
may come and go at any speed over 72 km/h (45 mph) during the first 10 minutes of operation, if
vibration continues after 10 minutes of driving at speeds greater than 72 km/h (45 mph), tire
flat-spotting can be ruled out as the cause for vibration.
6. If flat-spotting is the cause, provide the explanation that this has occurred due to the vehicle
being parked for long periods of time and that the
nature of the tire is to take a set. Refer to Corporate Bulletin Number 03-03-10-007E: Information
on Tire/Wheel Characteristics (Vibration, Balance, Shake, Flat Spotting) of GM Original Equipment
Tires.
7. If the road test indicates a shake/vibration exists, check the imbalance of each tire/wheel
assembly on a known, calibrated, off-car dynamic
balancer.Make sure the mounting surface of the wheel and the surface of the balancer are
absolutely clean and free of debris. Be sure to chose the proper cone/collet for the wheel, and
always use the pilot bore for centering. Never center the wheel using the hub-cap bore since it is
not a precision machined surface. If any assembly calls for more than 1/4 ounce on either rim
flange, remove all balance weights and rebalance to as close to zero as possible. If you can see
the vibration (along with feeling it) in the steering wheel (driving straight without your hands on the
wheel), it is very likely to be a tire/wheel first order (one pulse per revolution) disturbance. First
order disturbances can be caused by imbalance as well as non-uniformities in tires, wheels or
hubs. This first order frequency is too low for a human to hear, but if the amplitude is high enough,
it can be seen.
If a vibration or shake still exists after balancing, any out of round conditions, of the wheel, and
force variation conditions of the tire, must be addressed. Equipment such as the Hunter GSP9700
can address both (it is also a wheel balancer).
Tire radial force vibration (RFV) can be defined as the amount of stiffness variation the tire will
produce in one revolution under a constant load. Radial force variation is what the vehicle feels
because the load (weight) of the vehicle is always on the tires. Although free runout of tires (not
under load) is not always a good indicator of a smooth ride, it is critical that total tire/wheel
assembly runout be within specification.
Equipment such as the Hunter GSP9700 loads the tire, similar to on the vehicle, and measures
radial force variation of the tire/wheel assembly. Note that the wheel is affecting the tire's RFV
measurement at this point. To isolate the wheel, its runout must be measured. This can be easily
done on the Hunter, without the need to set up dial indicators. If the wheel meets the runout
specification, the tire's RFV can then be addressed.
After measuring the tire/wheel assembly under load, and the wheel alone, the machine then
calculates (predicts) the radial force variation of the tire. However, because this is a prediction that
can include mounting inaccuracies, and the load wheel is much smaller in diameter than used in
tire production, this type of service equipment should NOT be used to audit new tires. Rather, it
should be used as a service diagnostic tool to minimize radial force variation of the tire/wheel
assembly.
Equipment such as the Hunter GSP9700 does an excellent job of measuring wheel runout, and of
finding the low point of the wheel (for runout) and the high point of the tire (for radial force
variation). This allows the tire to be matched mounted to the wheel for lowest tire/wheel assembly
force variation.
The machine will simplify this process into easy steps. The following assembly radial force variation
numbers should be used as a guide:
When measuring RFV and match mounting tires perform the following steps.
Measuring Wheel Runout and Assembly Radial Force Variation
Important The completed worksheet at the end of this bulletin must be attached to the hard copy of
the repair order.
- Measure radial force variation and radial runout.
- If a road force/balancing machine is used, record the radial force variation (RFV) on the
worksheet at the end of this bulletin. It may be of benefit to have the lowest RFV assembly to the
front left corner. If the machine is not available and the EVA data suggests there is an issue, swap
the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem
still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those
tires onto the subject vehicle.
- If a runout/balancing machine is used, record the radial runout of the tire/wheel assemblies on the
worksheet at the end of this bulletin. If one or more of the tire/wheel assemblies are more than.040
in (1.02 mm), match mount the tire to the wheel to get below.040 in (1.02 mm). For sensitive
customers, readings of 0.030 inch (0.76 mm) or less are preferable, it may also be of benefit to
have the lowest runout assembly to the front left corner. If the machine is not available and the
EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the
back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do
not exhibit the same frequency and swap those tires
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Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force
Variation (RFV) > Page 1897
onto the subject vehicle.
- After match mounting, the tire/wheel assembly must be rebalanced.
If match mounting tires to in-spec wheels produces assembly values higher than these, tire
replacement may be necessary. Replacing tires at lower values will probably mean good tires are
being condemned. Because tires can sometimes become temporarily flat-spotted, which will affect
force variation, it is important that the vehicle be driven at least 16 km (10 mi) prior to measuring.
Tire pressure must also be adjusted to the usage pressure on the vehicle's tire placard prior to
measuring.
Most GM vehicles will tolerate radial force variation up to these levels. However, some vehicles are
more sensitive, and may require lower levels. Also, there are other tire parameters that equipment
such as the Hunter GSP9700 cannot measure that may be a factor. In such cases, TAC should be
contacted for further instructions.
Important
- When mounting a GM wheel to a wheel balancer/force variation machine, always use the wheel's
center pilot hole. This is the primary centering mechanism on all GM wheels; the bolt holes are
secondary. Usually a back cone method to the machine should be used. For added accuracy and
repeatability, a flange plate should be used to clamp the wheel onto the cone and machine. This
system is offered by all balancer manufacturers in GM's dealer program.
- Any type of service equipment that removes tread rubber by grinding, buffing or truing is NOT
recommended, and may void the tire warranty. However, tires may have been ground by the tire
company as part of their tire manufacturing process. This is a legitimate procedure.
Steering Wheel Shake Worksheet
When diagnosing vibration concerns, use the following worksheet in conjunction with the
appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI.
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force
Variation (RFV) > Page 1898
Refer to the appropriate section of SI for specifications and repair procedures that are related to the
vibration concern.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low Tire/Leaking Cast
Aluminum Wheels
Wheels: All Technical Service Bulletins Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels
TECHNICAL
Bulletin No.: 05-03-10-003F
Date: April 27, 2010
Subject: Low Tire Pressure, Leaking Cast Aluminum Wheels (Repair with Adhesive Sealant)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2010 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X with Cast Aluminum Wheels
Supercede: This bulletin is being revised to update the model years and the bulletin reference
information. Please discard Corporate Bulletin Number 05-03-10-003E (Section 03 - Suspension).
Condition
Some customers may comment on a low tire pressure condition.
Diagnosis of the low tire pressure condition indicates an air leak through the cast aluminum wheel.
Cause
Porosity in the cast aluminum wheel may be the cause.
Notice
This bulletin specifically addresses issues related to the wheel casting that may result in an air
leak. For issues related to corrosion of the wheel in service, please refer to Corporate Bulletin
Number 08-03-10-006C - Tire Slowly Goes Flat, Tire Air Loss, Low Tire Pressure Warning Light
Illuminated, Aluminum Wheel Bead Seat Corrosion (Clean and Resurface Wheel Bead Seat).
Correction
1. Remove the tire and wheel assembly from the vehicle. Refer to the appropriate service
procedure in SI. 2. Locate the leaking area by inflating the tire to 276 kPa (40 psi) and dipping the
tire/wheel assembly in a water bath, or use a spray bottle with soap
and water to locate the specific leak location.
Important
- If the porosity leak is located in the bead area of the aluminum rim (where the tire meets the rim),
the wheel should be replaced.
- If two or more leaks are located on one wheel, the wheel should be replaced.
3. If air bubbles are observed, mark the location.
- If the leak location is on the tire/rubber area, refer to Corporate Bulletin Number 04-03-10-001F Tire Puncture Repair Procedures for All Cars and Light Duty Trucks.
- If the leak is located on the aluminum wheel area, continue with the next step.
4. Inscribe a mark on the tire at the valve stem in order to indicate the orientation of the tire to the
wheel. 5. Dismount the tire from the wheel. Refer to Tire Mounting and Dismounting. 6. Remove
the tire pressure sensor. Refer to Tire Pressure Sensor removal procedure in SI. 7. Scuff the
INSIDE rim surface at the leak area with #80 grit paper and clean the area with general purpose
cleaner, such as 3M(R) General Purpose
Adhesive Cleaner, P/N 08984, or equivalent.
8. Apply a 3 mm (0.12 in) thick layer of Silicone - Adhesive/Sealant, P/N 12378478 (in Canada, use
88900041), or equivalent, to the leak area. 9. Allow for the adhesive/sealant to dry.
Notice Caution must be used when mounting the tire so as not to damage the sealer. Damaging
the repair area may result in an air leak.
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Bulletins > All Technical Service Bulletins for Wheels: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low Tire/Leaking Cast
Aluminum Wheels > Page 1903
10. Align the inscribed mark on the tire with the valve stem on the wheel. 11. Reinstall the Tire
Pressure Sensor. Refer to Tire Pressure Sensor installation procedure in SI. 12. Mount the tire on
the wheel. Refer to Tire Mounting and Dismounting. 13. Pressurize the tire to 276 kPa (40 psi) and
inspect for leaks. 14. Adjust tire pressure to meet the placard specification. 15. Balance the
tire/wheel assembly. Refer to Tire and Wheel Assembly Balancing - Off-Vehicle. 16. Install the tire
and wheel assembly onto the vehicle. Refer to the appropriate service procedure in SI.
Parts Information
Warranty Information (excluding Saab U.S. Models)
Important The Silicone - Adhesive/Sealant comes in a case quantity of six. ONLY charge warranty
one tube of adhesive/sealant per wheel repair.
For vehicles repaired under warranty, use:
One leak repair per wheel.
Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use the table above.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 04-03-10-012B > Feb > 08 > Wheels - Chrome Wheel Brake Dust
Accumulation/Pitting
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Brake Dust Accumulation/Pitting
Bulletin No.: 04-03-10-012B
Date: February 01, 2008
INFORMATION
Subject: Pitting and Brake Dust on Chrome wheels
Models: 2008 and Prior GM Passenger Cars and Trucks (including Saturn) 2008 and Prior
HUMMER H2, H3 2005-2008 Saab 9-7X
Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number
04-03-10-012A (Section 03 - Suspension).
Analysis of Returned Wheels
Chrome wheels returned under the New Vehicle Limited Warranty for pitting concerns have
recently been evaluated. This condition is usually most severe in the vent (or window) area of the
front wheels. This "pitting" may actually be brake dust that has been allowed to accumulate on the
wheel. The longer this accumulation builds up, the more difficult it is to remove.
Cleaning the Wheels
In all cases, the returned wheels could be cleaned to their original condition using GM Vehicle Care
Cleaner Wax, P/N 12377966 (in Canada, P/N 10952905). When using this product, you should
confine your treatment to the areas of the wheel that show evidence of the brake dust build-up.
This product is only for use on chromed steel or chromed aluminum wheels.
Parts Information
Warranty Information
Wheel replacement for this condition is NOT applicable under the terms of the New Vehicle Limited
Warranty.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 99-03-10-102 > Jun > 99 > Warranty - OE Chrome Plated
Aluminum Wheel ID
Wheels: All Technical Service Bulletins Warranty - OE Chrome Plated Aluminum Wheel ID
File In Section: 03 - Suspension
Bulletin No.: 99-03-10-102
Date: June, 1999
INFORMATION
Subject: Original Equipment Chrome Plated Aluminum Wheel Identification
Models: 1999 and Prior Passenger Cars and Light Duty Trucks
Chrome plated aluminum wheels have been returned to the Warranty Parts Center that are not the
original equipment (OE) components.
Original equipment chrome plated aluminum wheels can be identified by either a balance weight
clip retention groove (1) or a step (2) that is machined around both of the wheel's rim flanges. The
rim flanges (3) of painted original equipment aluminum wheels do not have a groove or a step.
Chrome plated aluminum wheels that do not have the wheel rim flange groove or step are
aftermarket chrome plated components and are NOT warrantable. Any aftermarket chrome wheels
received by the Warranty Parts Center will be charged back to the dealership.
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Bulletins > All Technical Service Bulletins for Wheels: > 72-05-05 > Aug > 97 > Warranty - Guidelines for Using E0420
Wheel Replace
Wheels: All Technical Service Bulletins Warranty - Guidelines for Using E0420 Wheel Replace
File In Section: Warranty Administration
Bulletin No.: 72-05-05
Date: August, 1997
WARRANTY ADMINISTRATION
Subject: Guidelines for Using EO42O Wheel Replace
Models: 1989-98 Passenger Cars and Light Duty Trucks
The purpose of this bulletin is to provide service personnel with guidelines for using the above
subject labor operation.
Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the
following:
^ Aluminum Wheels (including chrome plated) with Porosity - Wheels that exhibit porosity should
be repaired as described in the vehicle service manual. Wheels should not be replaced without
wholesale approval.
^ Aluminum Wheels (except chrome plated) with a "Finish Defect" - Wheels that exhibit a defect in
the finish, (i.e., discoloration or surface degradation) should be refinished as described in the
Corporate Service Bulletin Number 53-17-03A released in May, 1996.
^ Chrome Wheels - Wheels that are chromed and found to have a finish defect can only be
replaced.
^ Aluminum and chrome wheels replaced under warranty will be subject to random part review and
inspection. Those wheels inspected and found not to be defective and/or should have been
repaired, will be subject to charge back.
Wheels damaged by normal wear, road hazards, car wash brushes, or other physical or chemical
damage are not eligible for warranty coverage.
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing
Technical Service Bulletin # 531703A Date: 960501
Aluminum Wheels - Refinishing
File In Section: 10 - Body
Bulletin No.: 53-17-03A
Date: May, 1996
INFORMATION
Subject: Aluminum Wheel Refinishing
Models: 1991-96 Passenger Cars and Trucks
This bulletin is being revised to delete the 1990 model year and add the 1996 model year. Please
discard Corporate Bulletin Number 53-17-03 (Section 10 - Body).
This bulletin supersedes and cancels all previous service bulletins concerning the refinishing of
aluminum wheels. The purpose of this service bulletin is to assist dealerships in repairing the
discoloration or surface degradation that has occurred on styled aluminum wheels.
This bulletin provides NEW PROCEDURES AND SPECIFIC MATERIALS for the refinishing of
painted aluminum wheels or aluminum wheels with discoloration or surface degradation.
Important:
THE RE-MACHINING OF ALUMINUM WHEELS IS NOT RECOMMENDED. THE RE-CLEAR
COATING OF ALUMINUM WHEELS IS NO LONGER RECOMMENDED DUE TO CONCERNS OF
REPAIR DURABILITY
The new procedure requires the wheel surface be plastic media blasted to remove old paint or
clear coat. CHEMICAL STRIPPERS ARE NOT RECOMMENDED.
Material Required
System 1: DuPont Products
3939-S Cleaning Solvent 615/616 Etching Primer URO 5000 Primer Surfacer IMRON 6000
Basecoat 3440-S IMRON Clear
System 2: PPG Products
DX533 Aluminum Cleaner DX503 Aluminum Conditioner DP Epoxy Primer Deltron Basecoat
(DBC) Concept 2001 Clear Acrylic Urethane
System 3: Spies Hecker
Permahyd Silicone Remover 7090 Permahyd 1:1 Primer 4070 Permahyd 2:1 Surfacer 5080
Permahyd Base Coat Series 280/285 Permahyd H.S. Clearcoat 8060
Color Selection
If the wheels being painted were previously clearcoated aluminum, we would recommend using
Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a
very bright look. As an option to the customer, you may also use body color. For color
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Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing > Page
1920
selection and verification, refer to your paint manufacturer's color book. On wheels that were
previous clearcoated aluminum it is recommended that all four wheels and their center caps be
refinished to maintain color uniformity.
Important:
THE PRODUCTS LISTED MUST BE USED AS A SYSTEM. DO NOT MIX OTHER
MANUFACTURERS' PRODUCT LINES WITH THE REQUIRED MATERIALS. PRODUCTS
LISTED IN THIS BULLETIN HAVE SHOWN THE REQUIRED REPAIR DURABILITY, AND
CURRENTLY ARE THE ONLY PAINT SYSTEMS THAT MEET GM SPECIFICATION
4350M-A336.
Procedures
1. Remove wheels from vehicle. Tires may remain mounted on wheels.
2. Remove balance weights and mark their location on tire.
3. Wipe excess grease, etc. from wheels with wax and grease remover.
4. Have wheels plastic media blasted to remove clearcoat. FOR FURTHER INFORMATION ON
MEDIA BLASTING IN YOUR AREA, CALL US TECHNOLOGIES INC., CONTACT DAVE
ROSENBURG AT 1-800-634-9185.
Caution:
IT IS MANDATORY THAT ADEQUATE RESPIRATORY PROTECTION BE WORN. EXAMPLES
OF SUCH PROTECTION ARE: AIR LINE RESPIRATORS WITH FULL HOOD OR HALF MASK. IF
NOT AVAILABLE, USE A VAPOR/PARTICULATE RESPIRATOR THAT RESPIRATOR
MANUFACTURER RECOMMENDS AS EFFECTIVE FOR ISOCYANATE VAPOR AND MISTS
(UNLESS LOCAL REGULATIONS PREVAIL).
5. Painting Process
a. Refer to Attachments 1-3 for each System's individual formula and process.
b. After following the specific System's individual formula and process, follow these steps:
6. Unmask wheels.
7. Clean all wheel mounting surface of any corrosion, overspray, or dirt.
8. Install new coated balance weights, at marked locations.
9. Replace wheels on vehicle.
10. USE A TORQUE STICK ON AN IMPACT WRENCH, OR A TORQUE WRENCH TO
CONSISTENTLY AND UNIFORMLY FASTEN THE WHEEL TO THE SPECIFIED TORQUE FOR
THE VEHICLE. THE STAR PATTERN MUST BE FOLLOWED.
Important:
TORQUE STICKS MUST BE USED ANY TIME AN IMPACT WRENCH IS USED TO TIGHTEN
WHEEL NUTS.
Warranty Information
For vehicles repaired under warranty, use as shown.
Attachment 1 - DuPont Products
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Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing > Page
1921
Painting Process
System: Dupont Products
Paint Color Information: Corsican Silver WA EQ9283 Dupont # C9143, Sparkle Silver WA9967
Dupont # C9339
1. Wipe wheel with cleaning solvent: 3939-S, 3949-S or 3900-S.
2. Mask off tires.
Important:
3. Mask off all wheel mounting surfaces and wheel mount surfaces.
4. Apply two coats of 615/616-S etching primer to wheel allowing 10 minutes flash between coats.
Allow to dry for 30 minutes before applying primer coat.
5. Apply URO 5000 primer 1220/193-S + accelerator 389-S using two coats at 65-70 PSI at the
gun. Allow 12-15 minutes between coats. Force bake 30 minutes at 140°F (60°C).
6. Scuff sand using green Scotch-Brite pad.
7. Solvent wipe before top coating.
8. Apply IMRON 6000 base coat to wheel. 2-3 coats to hiding at 60-70 PSI allowing to flash
between coats. Base coat needs to dry 20-30 minutes before clearcoat is applied.
9. Apply 3440-S clearcoat to wheel using two coats at 60-70 PSI. Flash 10-15 minutes between
coats. 389-S can be used in basecoat and clearcoat to give faster set up times.
10. Allow overnight dry before reassemble. Can be baked for 30 minutes at 140°F (60°C).
Attachment 2 - PPG Products
Painting Process: PPG System
Paint Color Information: Corsican Silver WAEQ9283; PPG # DBC-3531, Sparkle Silver WA9967;
PPG # 35367
1. Wash entire wheel with aluminum cleaner DX533, mix 1:3 with water. Allow to react 2-3 minutes
and rinse thoroughly.
2. Wash entire wheel with aluminum conditioner DX5O3 straight from the container. Allow to react
2-3 minutes until pale gold or tan color develops. Rinse thoroughly and dry.
3. Mask off tires.
Important:
4. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
5. Apply 1-2 coats of DP Primer and allow to flash for 15-20 minutes.
6. Apply 2-3 coats of Deltron Basecoat (DBC) and allow to flash 20 minutes after the final coat.
7. Apply two (2) wet coats of Concept 2001 Acrylic urethane.
8. Flash 20 minutes and bake 140°F (60°C) for 30 minutes.
For more information contact your PPG Jobber.
Attachment 3 - Spies Hecker
Painting Process: Spies Hecker System
Paint Color Information: Corsican Silver AWEQ9283; SH-72913, Sparkle Silver WA9967;
SH-71912
1. Clean with Permahyd Silicone Remover 7090.
2. Mask off tires.
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Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing > Page
1922
Important:
3. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
4. Apply 1-1/2 coats of Permahyd 1:1 Primer 4070. Mix 1:1 with Permahyd Hardener 3070 as per
TDS.
5. Allow to flash for 30 minutes.
6. Apply two (2) coats of Permahyd 2:1 Surfacer 5080. Mix 2:1 with Permahyd Hardener 3071 as
per TDS.
7. Bake for 60 minutes at 140°F (60°C) or allow to flash for 3 hours at 68°F (20°C).
8. Apply Permahyd Base Coat Series 280/285 as per TDS.
9. Allow to flash 10 to 15 minutes.
10. Apply 1 to 2 coats of Permacron High Solid Clear Coat 8060 as per TDS.
11. Allow to flash 10 minutes. Then bake at 140°F (60°C) for 40 minutes.
For more information, contact your SPIES HECKER Jobber.
We believe these sources and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Staining/Pitting/Corrosion
INFORMATION
Bulletin No.: 00-03-10-002F
Date: April 21, 2011
Subject: Chemical Staining, Pitting, Corrosion and/or Spotted Appearance of Chromed Aluminum
Wheels
Models:
2012 and Prior GM Cars and Trucks
Supercede: This bulletin is being revised to update model years, suggest additional restorative
products and add additional corrosion information. Please discard Corporate Bulletin Number
00-03-10-002E (Section 03 - Suspension). Important You may give a copy of this bulletin to the
customer.
What is Chemical Staining of Chrome Wheels? Figure 1
Chemical staining in most cases results from acid based cleaners (refer to Figure 1 for an
example). These stains are frequently milky, black, or greenish in appearance. They result from
using cleaning solutions that contain acids on chrome wheels. Soap and water is usually sufficient
to clean wheels.
If the customer insists on using a wheel cleaner they should only use one that specifically states
that it is safe for chromed wheels and does not contain anything in the following list. (Dealers
should also survey any products they use during prep or normal cleaning of stock units for these
chemicals.)
- Ammonium Bifluoride (fluoride source for dissolution of chrome)
- Hydrofluoric Acid (directly dissolves chrome)
- Hydrochloric Acid (directly dissolves chrome)
- Sodium Dodecylbenzenesulfonic Acid
- Sulfamic Acid
- Phosphoric Acid
- Hydroxyacetic Acid
Notice
Many wheel cleaner instructions advise to take care to avoid contact with painted surfaces. Most
customers think of painted surfaces as the fenders, quarter panels and other exterior sheet metal.
Many vehicles have painted brake calipers. Acidic wheel cleaners may craze, crack, or discolor the
paint on the brake calipers. Damage from wheel cleaners is not covered under the vehicle new car
warranty. Soap and water applied with a soft brush is usually all that is required to clean the
calipers.
Whenever any wheel cleaner is used, it must be THOROUGHLY rinsed off of the wheel with clean,
clear water. Special care must be taken to rinse under the hub cap, balance weights, wheel nuts,
lug nut caps, between the wheel cladding and off the back side of the wheel. Wheels returned to
the Warranty Parts Center (WPC) that exhibit damage from wheel cleaners most often have the
damage around and under the wheel weight where the cleaner was incompletely flushed away.
Notice
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Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 1928
Do not use cleaning solutions that contain hydrofluoric, oxalic and most other acids on chrome
wheels (or any wheels).
If the customer is unsure of the chemical make-up of a particular wheel cleaner, it should be
avoided.
For wheels showing signs of milky staining from acidic cleaners, refer to Customer Assistance and
Instructions below.
Warranty of Stained Chrome Wheels
Stained wheels are not warrantable. Most acid based cleaners will permanently stain chrome
wheels. Follow-up with dealers has confirmed that such cleaners were used on wheels that were
returned to the Warranty Parts Center (WPC). Any stained wheels received by the WPC will be
charged back to the dealership. To assist the customer, refer to Customer Assistance and
Instructions below.
Pitting or Spotted Appearance of Chrome Wheels Figure 2
A second type or staining or finish disturbance may result from road chemicals, such as calcium
chloride used for dust control of unpaved roads. The staining will look like small pitting (refer to
Figure 2). This staining will usually be on the leading edges of each wheel spoke, but may be
uniformly distributed. If a vehicle must be operated under such conditions, the chrome wheels
should be washed with mild soap and water and thoroughly rinsed as soon as conveniently
possible.
Important Road chemicals, such as calcium chloride used for dust control of unpaved roads, can
also stain chrome wheels. The staining will look like small pitting. This staining will usually be on
the leading edges of each wheel spoke. This is explained by the vehicle traveling in the forward
direction while being splashed by the road chemical. If a vehicle must be operated under such
conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed
as soon as conveniently possible.
Warranty of Pitted or Spotted Chrome Wheels
Wheels returned with pitting or spotting as a result of road chemicals may be replaced one time.
Damage resulting from contact with these applied road chemicals is corrosive to the wheels finish
and may cause damage if the wheels are not kept clean.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean if they are operating the vehicle in an area that
applies calcium chloride or other dust controlling chemicals! "GM of Canada" dealers require prior
approval by the District Manager - Customer Care and Service Process (DM-CCSP).
"Stardust" Corrosion of Chrome Wheels Figure 3
A third type of finish disturbance results from prolonged exposure to brake dust and resultant
penetration of brake dust through the chrome. As brakes are applied hot particles of brake material
are thrown off and tend to be forced through the leading edge of the wheel spoke windows by
airflow. These
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 1929
hot particles embed themselves in the chrome layer and create a small pit. If the material is allowed
to sit on the wheel while it is exposed to moisture or salt, it will corrode the wheel beneath the
chrome leaving a pit or small blister in the chrome.
Heavy brake dust build-up should be removed from wheels by using GM Chrome Cleaner and
Polish, P/N 1050173 (in Canada use 10953013). For moderate cleaning, light brake dust build-up
or water spots use GM Swirl Remover Polish, P/N 12377965 (in Canada, use Meguiars
Plast-X(TM) Clear Plastic Cleaner and Polish #G12310C**). After cleaning, the wheel should be
waxed using GM Cleaner Wax, P/N 12377966 (in Canada, use Meguiars Cleaner Wax
#M0616C**), which will help protect the wheel from brake dust and reduce adhesion of any brake
dust that gets on the wheel surface. For general maintenance cleaning, PEEK Metal Polish† may
be used. It will clean and shine the chrome and leave behind a wax coating that may help protect
the finish.
Warranty of Stardust Corroded Chrome Wheels
Wheels returned with pitting or spotting as a result of neglect and brake dust build-up may be
replaced one time.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean and free of prolonged exposure to brake dust
build-up. "GM of Canada" dealers require prior approval by the District Manager - Customer Care
and Service Process (DM-CCSP).
Customer Assistance and Instructions
GM has looked for ways customers may improve the appearance of wheels damaged by acidic
cleaners. The following product and procedure has been found to dramatically improve the
appearance of stained wheels. For wheels that have milky stains caused by acidic cleaners try the
following:
Notice
THE 3M CHROME AND METAL POLISH REQUIRED FOR THIS PROCEDURE IS AN
EXTREMELY AGGRESSIVE POLISH/CLEANER. THE WHEELS MUST BE CLEANED BEFORE
APPLICATION TO AVOID SCRATCHING THE WHEEL SURFACE. THIS PRODUCT WILL
REDUCE THE THICKNESS OF THE CHROME PLATING ON THE WHEEL AND IF USED
INCORRECTLY OR EXCESSIVELY MAY REMOVE THE CHROME PLATING ALL TOGETHER,
EXPOSING A LESS BRIGHT AND BRASSY COLORED SUB-LAYER. FOLLOW INSTRUCTIONS
EXACTLY.
1. Wash the wheels with vigorously with soap and water. This step will clean and may reduce
wheel staining. Flood all areas of the wheel with water
to rinse.
2. Dry the wheels completely.
Notice Begin with a small section of the wheel and with light pressure buff off polish and examine
results. ONLY apply and rub with sufficient force and time to remove enough staining that you are
satisfied with the results. Some wheels may be stained to the extent that you may only achieve a
50% improvement while others may be able to be restored to the original lustre. IN ALL CASES,
only apply until the results are satisfactory.
3. Apply 3M Chrome and Metal Polish #39527* with a clean terry cloth towel. As you apply the
polish, the staining will be diminished. 4. When dry, buff off the polish with a clean portion of the
towel. 5. Repeat application of the 3M Chrome and Metal Polish until satisfied with the results. If
continued applications fail to improve the appearance
further discontinue use.
This procedure will improve the appearance of the wheels and may, with repeated applications,
restore the finish dramatically. For wheels that exhibit spotting from road chemicals the above
procedure may marginally improve the condition but will not restore the finish or remove the pitting.
In this type of staining the wheel finish has actually been removed in spots and no manner of
cleaning will restore the finish.
†*We believe this source and their products to be reliable. There may be additional manufacturers
of such products/materials. General Motors does not endorse, indicate any preference for or
assume any responsibility for the products or material from this firm or for any such items that may
be available from other sources.
Parts Information
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Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 1930
*This product is currently available from 3M. To obtain information for your local retail location
please call 3M at 1-888-364-3577.
**This product is currently available from Meguiars (Canada). To obtain information for your local
retail location please call Meguiars at 1-800-347-5700 or at www.meguiarscanada.com.
^ This product is currently available from Tri-Peek International. To obtain information for your local
retail location please call Tri-Peek at
1-877-615-4272 or at www.tripeek.com.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires - Refinishing Aluminum
Wheels
Wheels: All Technical Service Bulletins Wheels/Tires - Refinishing Aluminum Wheels
INFORMATION
Bulletin No.: 99-08-51-007E
Date: March 17, 2011
Subject: Refinishing Aluminum Wheels
Models:
2012 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add additional model years. Please discard Corporate
Bulletin Number 99-08-51-007D (Section 08 - Body and Accessories).
This bulletin updates General Motor's position on refinishing aluminum wheels. GM does not
endorse any repairs that involve welding, bending, straightening or re-machining. Only cosmetic
refinishing of the wheel's coatings, using recommended procedures, is allowed.
Evaluating Damage
In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion,
scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be
sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the
wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been
refinished by an outside company must be returned to the same vehicle. The Dealer must record
the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to
Refinisher's Responsibility - Outside Company later in this bulletin.
Aluminum Wheel Refinishing Recommendations
- Chrome-plated aluminum wheels Re-plating these wheels is not recommended.
- Polished aluminum wheels These wheels have a polyester or acrylic clearcoat on them. If the
clearcoat is damaged, refinishing is possible. However, the required refinishing process cannot be
performed in the dealer environment. Refer to Refinisher's Responsibility - Outside Company later
in this bulletin.
- Painted aluminum wheels These wheels are painted using a primer, color coat, and clearcoat
procedure. If the paint is damaged, refinishing is possible. As with polished wheels, all original
coatings must be removed first. Media blasting is recommended. Refer to GM Aluminum
Refinishing Bulletin #53-17-03A for the re-painting of this type of wheel.
- Bright, machined aluminum wheels These wheels have a polyester or acrylic clearcoat on them.
In some cases, the recessed "pocket" areas of the wheel may be painted. Surface refinishing is
possible. The wheel must be totally stripped by media blasting or other suitable means. The wheel
should be resurfaced by using a sanding process rather than a machining process. This allows the
least amount of material to be removed.
Important Do not use any re-machining process that removes aluminum. This could affect the
dimensions and function of the wheel.
Painting is an option to re-clearcoating polished and bright machined aluminum wheels. Paint will
better mask any surface imperfections and is somewhat more durable than clearcoat alone. GM
recommends using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle
SILVER WA9967 for a very bright look. As an option, the body color may also be used. When using
any of the painting options, it is recommended that all four wheels be refinished in order to maintain
color uniformity. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for specific procedures
and product recommendations.
Refinisher's Responsibility - Outside Company
Important Some outside companies are offering wheel refinishing services. Such refinished wheels
will be permanently marked by the refinisher and are warranted by the refinisher. Any process that
re-machines or otherwise re-manufactures the wheel should not be used.
A refinisher's responsibility includes inspecting for cracks using the Zyglo system or the equivalent.
Any cracked wheels must not be refinished. No welding, hammering or reforming of any kind is
allowed. The wheel ID must be recorded and follow the wheel throughout the process in order to
assure that the same wheel is returned. A plastic media blast may be used for clean up of the
wheel. Hand and/or lathe sanding of the machined surface and the wheel window is allowed.
Material removal, though, must be kept to a minimum. Re-machining of the wheel is not allowed.
Paint and/or clear coat must not be present on the following surfaces: the nut chamfers, the wheel
mounting surfaces and the wheel pilot hole. The refinisher must permanently ID stamp the wheel
and warrant the painted/clearcoated surfaces for a minimum of one year or the remainder of the
new vehicle warranty, whichever is
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires - Refinishing Aluminum
Wheels > Page 1935
longer.
Important Whenever a wheel is refinished, the mounting surface and the wheel nut contact
surfaces must not be painted or clearcoated. Coating these surfaces could affect the wheel nut
torque.
When re-mounting a tire on an aluminum wheel, coated balance weights must be used in order to
reduce the chance of future cosmetic damage.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions
Wheels: All Technical Service Bulletins Wheels - Changing Procedures/Precautions
INFORMATION
Bulletin No.: 06-03-10-010A
Date: June 09, 2010
Subject: Information on Proper Wheel Changing Procedures and Cautions
Models:
2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER Models 2005-2009 Saab
9-7X 2005-2009 Saturn Vehicles
Attention:
Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel
Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and
reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel
installation. Always refer to SI for wheel lug nut torque specifications and complete jacking
instructions for safe wheel changing.
Supercede: This bulletin is being revised to include the 2011 model year and update the available
special tool list. Please discard Corporate Bulletin Number 06-03-10-010 (Section 03 Suspension).
Frequency of Wheel Changes - Marketplace Driven
Just a few years ago, the increasing longevity of tires along with greater resistance to punctures
had greatly reduced the number of times wheels were removed to basically required tire rotation
intervals. Today with the booming business in accessory wheels/special application tires (such as
winter tires), consumers are having tire/wheel assemblies removed - replaced - or installed more
than ever. With this increased activity, it opens up more of a chance for error on the part of the
technician. This bulletin will review a few of the common concerns and mistakes to make yourself
aware of.
Proper Servicing Starts With the Right Tools
The following tools have been made available to assist in proper wheel and tire removal and
installation.
- J 41013 Rotor Resurfacing Kit (or equivalent)
- J 42450-A Wheel Hub Resurfacing Kit (or equivalent)
Corroded Surfaces
One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle.
Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened
wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed
away from water splash. This action may result in clearance at the mating surface of the wheel and
an under-torqued condition.
Caution
Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or
brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting
surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is
moving, possibly resulting in a loss of control or personal injury.
Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If
corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding
pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating
surface.
The J 41013 (or equivalent) can be used to clean the following surfaces:
- The hub mounting surface
- The brake rotor mounting surface
- The wheel mounting surface
Use the J 42450-A (or equivalent) to clean around the base of the studs and the hub.
Lubricants, Grease and Fluids
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Bulletins > All Other Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 1940
Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in
removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to
installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper
readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY.
Notice
Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or
drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to
clean, dry wheel studs and surfaces ONLY. Beginning with 2011 model year vehicles, put a light
coating of grease, GM P/N 1051344 (in Canada, P/N 9930370), on the inner surface of the wheel
pilot hole to prevent wheel seizure to the axle or bearing hub.
Wheel Stud and Lug Nut Damage
Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse.
You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not
retain properly, yet give the impression of fully tightening. Always inspect and replace any
component suspected of damage.
Tip
Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged
BEFORE tightening the nut.
Important If the vehicle has directional tread tires, verify the directional arrow on the outboard side
of the tire is pointing in the direction of forward rotation.
Wheel Nut Tightening and Torque
Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid
additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown
for each vehicle in SI. Always observe the proper wheel nut tightening sequence as shown below in
order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off
center resulting in vibration.
The Most Important Service You Provide
While the above information is well known, and wheel removal so common, technicians run the risk
of becoming complacent on this very important
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 1941
service operation. A simple distraction or time constraint that rushes the job may result in personal
injury if the greatest of care is not exercised. Make it a habit to double check your work and to
always side with caution when installing wheels.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 04-03-10-012B > Feb > 08 > Wheels - Chrome Wheel Brake Dust
Accumulation/Pitting
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Brake Dust Accumulation/Pitting
Bulletin No.: 04-03-10-012B
Date: February 01, 2008
INFORMATION
Subject: Pitting and Brake Dust on Chrome wheels
Models: 2008 and Prior GM Passenger Cars and Trucks (including Saturn) 2008 and Prior
HUMMER H2, H3 2005-2008 Saab 9-7X
Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number
04-03-10-012A (Section 03 - Suspension).
Analysis of Returned Wheels
Chrome wheels returned under the New Vehicle Limited Warranty for pitting concerns have
recently been evaluated. This condition is usually most severe in the vent (or window) area of the
front wheels. This "pitting" may actually be brake dust that has been allowed to accumulate on the
wheel. The longer this accumulation builds up, the more difficult it is to remove.
Cleaning the Wheels
In all cases, the returned wheels could be cleaned to their original condition using GM Vehicle Care
Cleaner Wax, P/N 12377966 (in Canada, P/N 10952905). When using this product, you should
confine your treatment to the areas of the wheel that show evidence of the brake dust build-up.
This product is only for use on chromed steel or chromed aluminum wheels.
Parts Information
Warranty Information
Wheel replacement for this condition is NOT applicable under the terms of the New Vehicle Limited
Warranty.
Disclaimer
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 99-03-10-102 > Jun > 99 > Warranty - OE Chrome Plated Aluminum
Wheel ID
Wheels: All Technical Service Bulletins Warranty - OE Chrome Plated Aluminum Wheel ID
File In Section: 03 - Suspension
Bulletin No.: 99-03-10-102
Date: June, 1999
INFORMATION
Subject: Original Equipment Chrome Plated Aluminum Wheel Identification
Models: 1999 and Prior Passenger Cars and Light Duty Trucks
Chrome plated aluminum wheels have been returned to the Warranty Parts Center that are not the
original equipment (OE) components.
Original equipment chrome plated aluminum wheels can be identified by either a balance weight
clip retention groove (1) or a step (2) that is machined around both of the wheel's rim flanges. The
rim flanges (3) of painted original equipment aluminum wheels do not have a groove or a step.
Chrome plated aluminum wheels that do not have the wheel rim flange groove or step are
aftermarket chrome plated components and are NOT warrantable. Any aftermarket chrome wheels
received by the Warranty Parts Center will be charged back to the dealership.
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Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 72-05-05 > Aug > 97 > Warranty - Guidelines for Using E0420 Wheel
Replace
Wheels: All Technical Service Bulletins Warranty - Guidelines for Using E0420 Wheel Replace
File In Section: Warranty Administration
Bulletin No.: 72-05-05
Date: August, 1997
WARRANTY ADMINISTRATION
Subject: Guidelines for Using EO42O Wheel Replace
Models: 1989-98 Passenger Cars and Light Duty Trucks
The purpose of this bulletin is to provide service personnel with guidelines for using the above
subject labor operation.
Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the
following:
^ Aluminum Wheels (including chrome plated) with Porosity - Wheels that exhibit porosity should
be repaired as described in the vehicle service manual. Wheels should not be replaced without
wholesale approval.
^ Aluminum Wheels (except chrome plated) with a "Finish Defect" - Wheels that exhibit a defect in
the finish, (i.e., discoloration or surface degradation) should be refinished as described in the
Corporate Service Bulletin Number 53-17-03A released in May, 1996.
^ Chrome Wheels - Wheels that are chromed and found to have a finish defect can only be
replaced.
^ Aluminum and chrome wheels replaced under warranty will be subject to random part review and
inspection. Those wheels inspected and found not to be defective and/or should have been
repaired, will be subject to charge back.
Wheels damaged by normal wear, road hazards, car wash brushes, or other physical or chemical
damage are not eligible for warranty coverage.
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Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing
Technical Service Bulletin # 531703A Date: 960501
Aluminum Wheels - Refinishing
File In Section: 10 - Body
Bulletin No.: 53-17-03A
Date: May, 1996
INFORMATION
Subject: Aluminum Wheel Refinishing
Models: 1991-96 Passenger Cars and Trucks
This bulletin is being revised to delete the 1990 model year and add the 1996 model year. Please
discard Corporate Bulletin Number 53-17-03 (Section 10 - Body).
This bulletin supersedes and cancels all previous service bulletins concerning the refinishing of
aluminum wheels. The purpose of this service bulletin is to assist dealerships in repairing the
discoloration or surface degradation that has occurred on styled aluminum wheels.
This bulletin provides NEW PROCEDURES AND SPECIFIC MATERIALS for the refinishing of
painted aluminum wheels or aluminum wheels with discoloration or surface degradation.
Important:
THE RE-MACHINING OF ALUMINUM WHEELS IS NOT RECOMMENDED. THE RE-CLEAR
COATING OF ALUMINUM WHEELS IS NO LONGER RECOMMENDED DUE TO CONCERNS OF
REPAIR DURABILITY
The new procedure requires the wheel surface be plastic media blasted to remove old paint or
clear coat. CHEMICAL STRIPPERS ARE NOT RECOMMENDED.
Material Required
System 1: DuPont Products
3939-S Cleaning Solvent 615/616 Etching Primer URO 5000 Primer Surfacer IMRON 6000
Basecoat 3440-S IMRON Clear
System 2: PPG Products
DX533 Aluminum Cleaner DX503 Aluminum Conditioner DP Epoxy Primer Deltron Basecoat
(DBC) Concept 2001 Clear Acrylic Urethane
System 3: Spies Hecker
Permahyd Silicone Remover 7090 Permahyd 1:1 Primer 4070 Permahyd 2:1 Surfacer 5080
Permahyd Base Coat Series 280/285 Permahyd H.S. Clearcoat 8060
Color Selection
If the wheels being painted were previously clearcoated aluminum, we would recommend using
Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a
very bright look. As an option to the customer, you may also use body color. For color
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing > Page 1958
selection and verification, refer to your paint manufacturer's color book. On wheels that were
previous clearcoated aluminum it is recommended that all four wheels and their center caps be
refinished to maintain color uniformity.
Important:
THE PRODUCTS LISTED MUST BE USED AS A SYSTEM. DO NOT MIX OTHER
MANUFACTURERS' PRODUCT LINES WITH THE REQUIRED MATERIALS. PRODUCTS
LISTED IN THIS BULLETIN HAVE SHOWN THE REQUIRED REPAIR DURABILITY, AND
CURRENTLY ARE THE ONLY PAINT SYSTEMS THAT MEET GM SPECIFICATION
4350M-A336.
Procedures
1. Remove wheels from vehicle. Tires may remain mounted on wheels.
2. Remove balance weights and mark their location on tire.
3. Wipe excess grease, etc. from wheels with wax and grease remover.
4. Have wheels plastic media blasted to remove clearcoat. FOR FURTHER INFORMATION ON
MEDIA BLASTING IN YOUR AREA, CALL US TECHNOLOGIES INC., CONTACT DAVE
ROSENBURG AT 1-800-634-9185.
Caution:
IT IS MANDATORY THAT ADEQUATE RESPIRATORY PROTECTION BE WORN. EXAMPLES
OF SUCH PROTECTION ARE: AIR LINE RESPIRATORS WITH FULL HOOD OR HALF MASK. IF
NOT AVAILABLE, USE A VAPOR/PARTICULATE RESPIRATOR THAT RESPIRATOR
MANUFACTURER RECOMMENDS AS EFFECTIVE FOR ISOCYANATE VAPOR AND MISTS
(UNLESS LOCAL REGULATIONS PREVAIL).
5. Painting Process
a. Refer to Attachments 1-3 for each System's individual formula and process.
b. After following the specific System's individual formula and process, follow these steps:
6. Unmask wheels.
7. Clean all wheel mounting surface of any corrosion, overspray, or dirt.
8. Install new coated balance weights, at marked locations.
9. Replace wheels on vehicle.
10. USE A TORQUE STICK ON AN IMPACT WRENCH, OR A TORQUE WRENCH TO
CONSISTENTLY AND UNIFORMLY FASTEN THE WHEEL TO THE SPECIFIED TORQUE FOR
THE VEHICLE. THE STAR PATTERN MUST BE FOLLOWED.
Important:
TORQUE STICKS MUST BE USED ANY TIME AN IMPACT WRENCH IS USED TO TIGHTEN
WHEEL NUTS.
Warranty Information
For vehicles repaired under warranty, use as shown.
Attachment 1 - DuPont Products
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing > Page 1959
Painting Process
System: Dupont Products
Paint Color Information: Corsican Silver WA EQ9283 Dupont # C9143, Sparkle Silver WA9967
Dupont # C9339
1. Wipe wheel with cleaning solvent: 3939-S, 3949-S or 3900-S.
2. Mask off tires.
Important:
3. Mask off all wheel mounting surfaces and wheel mount surfaces.
4. Apply two coats of 615/616-S etching primer to wheel allowing 10 minutes flash between coats.
Allow to dry for 30 minutes before applying primer coat.
5. Apply URO 5000 primer 1220/193-S + accelerator 389-S using two coats at 65-70 PSI at the
gun. Allow 12-15 minutes between coats. Force bake 30 minutes at 140°F (60°C).
6. Scuff sand using green Scotch-Brite pad.
7. Solvent wipe before top coating.
8. Apply IMRON 6000 base coat to wheel. 2-3 coats to hiding at 60-70 PSI allowing to flash
between coats. Base coat needs to dry 20-30 minutes before clearcoat is applied.
9. Apply 3440-S clearcoat to wheel using two coats at 60-70 PSI. Flash 10-15 minutes between
coats. 389-S can be used in basecoat and clearcoat to give faster set up times.
10. Allow overnight dry before reassemble. Can be baked for 30 minutes at 140°F (60°C).
Attachment 2 - PPG Products
Painting Process: PPG System
Paint Color Information: Corsican Silver WAEQ9283; PPG # DBC-3531, Sparkle Silver WA9967;
PPG # 35367
1. Wash entire wheel with aluminum cleaner DX533, mix 1:3 with water. Allow to react 2-3 minutes
and rinse thoroughly.
2. Wash entire wheel with aluminum conditioner DX5O3 straight from the container. Allow to react
2-3 minutes until pale gold or tan color develops. Rinse thoroughly and dry.
3. Mask off tires.
Important:
4. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
5. Apply 1-2 coats of DP Primer and allow to flash for 15-20 minutes.
6. Apply 2-3 coats of Deltron Basecoat (DBC) and allow to flash 20 minutes after the final coat.
7. Apply two (2) wet coats of Concept 2001 Acrylic urethane.
8. Flash 20 minutes and bake 140°F (60°C) for 30 minutes.
For more information contact your PPG Jobber.
Attachment 3 - Spies Hecker
Painting Process: Spies Hecker System
Paint Color Information: Corsican Silver AWEQ9283; SH-72913, Sparkle Silver WA9967;
SH-71912
1. Clean with Permahyd Silicone Remover 7090.
2. Mask off tires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheels > Component Information > Technical Service
Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels - Refinishing > Page 1960
Important:
3. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
4. Apply 1-1/2 coats of Permahyd 1:1 Primer 4070. Mix 1:1 with Permahyd Hardener 3070 as per
TDS.
5. Allow to flash for 30 minutes.
6. Apply two (2) coats of Permahyd 2:1 Surfacer 5080. Mix 2:1 with Permahyd Hardener 3071 as
per TDS.
7. Bake for 60 minutes at 140°F (60°C) or allow to flash for 3 hours at 68°F (20°C).
8. Apply Permahyd Base Coat Series 280/285 as per TDS.
9. Allow to flash 10 to 15 minutes.
10. Apply 1 to 2 coats of Permacron High Solid Clear Coat 8060 as per TDS.
11. Allow to flash 10 minutes. Then bake at 140°F (60°C) for 40 minutes.
For more information, contact your SPIES HECKER Jobber.
We believe these sources and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Bearing > Component Information > Adjustments
Wheel Bearing: Adjustments
FRONT WHEEL BEARINGS ADJUSTMENT
Fig. 2 Front Wheel Bearing Adjustment
1. While rotating wheel forward, torque spindle nut to 12 ft. lbs., Fig. 2. 2. Back off nut until just
loose then hand tighten nut and back it off again until either hole in spindle lines up with hole in nut.
Do not back off nut
more than 1/2 flat.
3. Install new cotter pin. With wheel bearing properly adjusted, there will be .001-.005 inch end
play.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Bearing > Component Information > Adjustments
> Page 1964
Wheel Bearing: Service and Repair
FRONT WHEEL BEARINGS
Fig. 3 Hub & Wheel Bearing Replacement
1. Raise car and remove front wheels. 2. On models equipped with anti-lock brake systems,
remove right and left wheel speed sensors as follows:
a. Under vehicle hood, disconnect speed sensor electrical harness. b. Raise and support vehicle,
then remove speed sensor harness bracket attaching bolt. c. Remove speed sensor to steering
knuckle attaching bolt, then remove speed sensor and bracket assembly and position aside. d.
Reverse procedure to install. Install wheel speed sensors by hand. Do not hammer sensors into
position, as damage may result.
3. On all models, remove bolts holding brake caliper to its mounting and insert a fabricated block
(11/16 x 1 1/16 x 2 inches in length) between
brake pads as caliper is being removed. Once removed, caliper can be wired or secured in some
manner away from disc.
4. Remove spindle nut and hub and disc assembly. Grease retainer and inner wheel bearing can
now be removed, Fig. 3. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Fastener > Component Information > Technical
Service Bulletins > Customer Interest for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels - Plastic Wheel Nut Covers
Loose/Missing
Wheel Fastener: Customer Interest Wheels - Plastic Wheel Nut Covers Loose/Missing
Bulletin No.: 01-03-10-009A
Date: July 27, 2004
TECHNICAL
Subject: Plastic Wheel Nut Covers Missing and/or Loose (Replace Missing Covers and Add
Sealant to All Covers)
Models: 2005 and All Prior Passenger Cars (Except All Cadillac Models and Pontiac GTO)
with Plastic Wheel Nut Covers
Supercede:
This bulletin is being revised to add additional models years. Please discard Corporate Bulletin
Number 01-03-10-009.
Condition
Some customers may comment that the plastic wheel nut covers are missing and/or loose.
Correction
Important:
^ DO NOT USE a silicone-based adhesive.
^ Do not apply the *permatex(R) around the threads in a circular pattern.
^ Apply a single bead across the threads approximately 10 mm (0.4 in) in length, 5 mm (0.2 in) in
height and 5 mm (0.2 in) in width.
Replace any missing plastic wheel nut covers with the appropriate covers and apply Permatex(R) #
2 Form A Gasket Sealant(R) to the threads of all the plastic wheel nut covers. Tighten finger tight
plus a 1/4 turn with a hand wrench.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products from this firm or for any other such items which may be available from other sources.
Permatex(R) # 2 Form A Gasket Sealant(R) part numbers (available at your local parts supplier)
^ P/N 80009 (2A/2AR) - 44 ml (1.5 oz) tube boxed
^ P/N 80015 (2AR) - 44 ml (1.5 oz) tube carded
^ P/N 80010 (2B/2BR) - 89 ml (3 oz) tube boxed
^ P/N 80016 (2BR) - 89 ml (3 oz) tube carded
^ P/N 80011 (2C) - 325 ml (11 oz) tube boxed
Warranty Information
For vehicles repaired under warranty, use the table.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Fastener > Component Information > Technical
Service Bulletins > Customer Interest for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels - Plastic Wheel Nut Covers
Loose/Missing > Page 1973
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Fastener > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels - Plastic Wheel
Nut Covers Loose/Missing
Wheel Fastener: All Technical Service Bulletins Wheels - Plastic Wheel Nut Covers Loose/Missing
Bulletin No.: 01-03-10-009A
Date: July 27, 2004
TECHNICAL
Subject: Plastic Wheel Nut Covers Missing and/or Loose (Replace Missing Covers and Add
Sealant to All Covers)
Models: 2005 and All Prior Passenger Cars (Except All Cadillac Models and Pontiac GTO)
with Plastic Wheel Nut Covers
Supercede:
This bulletin is being revised to add additional models years. Please discard Corporate Bulletin
Number 01-03-10-009.
Condition
Some customers may comment that the plastic wheel nut covers are missing and/or loose.
Correction
Important:
^ DO NOT USE a silicone-based adhesive.
^ Do not apply the *permatex(R) around the threads in a circular pattern.
^ Apply a single bead across the threads approximately 10 mm (0.4 in) in length, 5 mm (0.2 in) in
height and 5 mm (0.2 in) in width.
Replace any missing plastic wheel nut covers with the appropriate covers and apply Permatex(R) #
2 Form A Gasket Sealant(R) to the threads of all the plastic wheel nut covers. Tighten finger tight
plus a 1/4 turn with a hand wrench.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products from this firm or for any other such items which may be available from other sources.
Permatex(R) # 2 Form A Gasket Sealant(R) part numbers (available at your local parts supplier)
^ P/N 80009 (2A/2AR) - 44 ml (1.5 oz) tube boxed
^ P/N 80015 (2AR) - 44 ml (1.5 oz) tube carded
^ P/N 80010 (2B/2BR) - 89 ml (3 oz) tube boxed
^ P/N 80016 (2BR) - 89 ml (3 oz) tube carded
^ P/N 80011 (2C) - 325 ml (11 oz) tube boxed
Warranty Information
For vehicles repaired under warranty, use the table.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Fastener > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels - Plastic Wheel
Nut Covers Loose/Missing > Page 1979
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Wheels and Tires > Wheel Fastener > Component Information > Technical
Service Bulletins > Page 1980
Wheel Fastener: Specifications
Wheel Nuts ..........................................................................................................................................
................................................ 140 Nm (100 ft lb)
CAUTION: If penetrating oil gets on the vertical surfaces between the wheel and the rotor or brake
drum. it could cause the wheel to work loose as the vehicle is driven, resulting in a loss of control
and an injury accident. Never use heat to loosen a tight wheel. It can shorten the life of the wheel,
bolts or spindle and bearings. Wheel nuts must be tightened in sequence and to the proper torque
to avoid bending the wheel or rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Maintenance > Vehicle Lifting > Component Information > Service and Repair
Vehicle Lifting: Service and Repair
Vehicle Lift Points
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Compression Check > System Information >
Specifications
Compression Check: Specifications
The lowest reading cylinder should not be less than 70% of the highest and no cylinder reading
should be less than 689 kPa (100 psi). Perform compression test with engine at normal operating
temperature, spark plugs removed and throttle wide open.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Camshaft,
Engine > Component Information > Specifications > Camshaft Journal & Lifter Specs
Camshaft: Specifications Camshaft Journal & Lifter Specs
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Camshaft Journal Diameter .................................................................................................................
............................................................ 1.8677-1.8697 Camshaft Endplay ..........................................
.................................................................................................................................................
0.0040-0.0120
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Camshaft,
Engine > Component Information > Specifications > Camshaft Journal & Lifter Specs > Page 1994
Camshaft: Specifications Camshaft Lift Specs
Int. ........................................................................................................................................................
.......................................................................... .279 Exh. ..................................................................
..............................................................................................................................................................
. .286
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Camshaft,
Engine > Component Information > Specifications > Page 1995
Camshaft: Service and Repair
Fig. 10 Camshaft Removal
1. Remove intake manifold as described under "Intake Manifold Service and Repair." 2. Remove oil
pump drive and driveshaft. 3. Remove valve covers, rocker arms and push rods. Keep rocker arms
and push rods in order so they can be installed in same locations. 4. Remove accessory drive
belt(s), then remove upper fan shroud. 5. Remove radiator. 6. On models equipped with A/C,
discharge refrigerant system and remove condenser. 7. On all models remove timing chain as
described under "Timing Chain, Service and Repair. 8. Remove grille. 9. Remove valve lifters.
Keep valve lifters in order so they can be installed in same locations.
10. Install three 5/16-18 x 4 inch bolts in camshaft bolt holes, then carefully remove camshaft,
Fig.10. 11. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Lifter / Lash
Adjuster, Valve > Component Information > Service and Repair
Lifter / Lash Adjuster: Service and Repair
Fig. 8 Exploded View Of Hydraulic Valve Lifter
Valve lifters can be lifted from their bores after removing rocker arms and push rods and intake
manifold. Adjustable pliers with protected jaws may be used to remove lifters which are stuck due
to carbon or varnish deposits. Fig.8. illustrates the type of valve lifter used.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Push Rod >
Component Information > Service and Repair
Push Rod: Service and Repair
On engines that use push rods with a hardened insert at one end, the hardened end is identified by
a color stripe and should always be installed toward the rocker arm during assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Rocker Arm
Assembly > Component Information > Adjustments
Rocker Arm Assembly: Adjustments
Fig. 5 Valve Lash Adjustment
Adjust valves, Fig.5, with engine at normal operating temperature. Rotate engine until No. 1
cylinder is in position to fire. Adjust exhaust valves 1-3-4-8 and intake valves 1-2-5-7. Crank engine
one complete revolution, then adjust exhaust valves 2-5-6-7 and intake vales 3-4-6-8.
On all engines, the following procedure, performed with the engine running, should only be
performed if readjustment is required.
1. After engine has been warmed up to normal operating temperature, remove valve cover and
install a new valve cover gasket. 2. With engine running at idle speed, back off valve rocker arm
nut until rocker arm starts to clatter. 3. Turn rocker arm nut down slowly until clatter just stops. This
is the zero lash position. 4. Turn nut down 1/4 additional turn and pause 10 seconds until engine
runs smoothly. Repeat additional 1/4 turns, pausing 10 seconds each time,
until nut has been turned down the number of turns listed in "Valve Clearance Specifications chart
from the zero lash position. This preload adjustment must be done slowly to allow lifter to adjust
itself to prevent the possibility of interference between valve head and top of piston, which might
result in internal damage and/or bent push rods. Noisy lifters should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Rocker Arm
Assembly > Component Information > Service and Repair > Rocker Arm
Rocker Arm Assembly: Service and Repair Rocker Arm
When replacing rocker arms or rocker arm balls, bearing surfaces of rocker arms and balls should
be coated with pre-lube part No. 3755008 or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Camshaft, Lifters and Push Rods > Rocker Arm
Assembly > Component Information > Service and Repair > Rocker Arm > Page 2007
Rocker Arm Assembly: Service and Repair Rocker Arm Studs Replace
Fig. 6 Rocker Arm Stud Removal
Fig. 7 Rocker Arm Stud Installation
If studs are loose in cylinder head, .003 inch or .013 inch oversize studs may be installed after
reaming holes with a proper size reamer.
1. Remove old stud by placing a suitable spacer, Fig.6. over stud. Install nut and flat washer and
remove stud by turning nut. 2. Ream hole for oversize stud. 3. Coat press-fit area of stud with rear
axle lube. Then install new stud, Fig.7. If tool shown is used, it should bottom on the head.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Connecting Rod
Bearing > Component Information > Service and Repair
Connecting Rod Bearing: Service and Repair
Connecting rod bearings are available in standard and undersizes of .001, .002, .010 and .020
inch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Connecting Rod,
Engine > Component Information > Specifications
Connecting Rod: Specifications
Torque Specifications 1994 47 ft.lb
1995-1996 20 ft.lb
then tighten each nut an additional 55 degrees
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Crankshaft Main
Bearing > Component Information > Service and Repair
Crankshaft Main Bearing: Service and Repair
Main bearings are available in standard and undersizes of .001, .002, .009, .010 and .020 inch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Crankshaft, Engine >
Component Information > Specifications > Main Bearing Torque Specifications
Crankshaft: Specifications Main Bearing Caps
Main Bearing Caps
Torque Specifications 77 ft.lb
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Crankshaft, Engine >
Component Information > Specifications > Main Bearing Torque Specifications > Page 2022
Crankshaft: Specifications Crankshaft Dimensions
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Crankshaft
Standard Journal Diameter
Main Bearing .......................................................................................................................................
.................................................................. [05] Crank Pin ...................................................................
........................................................................................................................... 2.0978-2.0998
Out of Round All [01] ...........................................................................................................................
.................................................................. 0.001 Taper All [01] ..........................................................
................................................................................................................................................ 0.001
Bearing Clearance
Main Bearings ......................................................................................................................................
...................................................................... [07] Connecting Rod Bearings ......................................
................................................................................................................................... 0.0013-0.0035
Thrust Bearing Clearance ....................................................................................................................
........................................................ 0.001-0.007
Connecting Rod Side Clearance .........................................................................................................
................................................................ 0.006-0.014
[01] Maximum. [05] Diameter No. 1, 2.4484-2.4493 inches] diameter No. 2, 3 & 4, 2.4481-2.4490
inches] journal No. 5, 2.4479-2.4488 inches. [07] Journal No. 1, 0.0010-0.0015 inch] journal No. 2,
3 & 4, .0011-.0025 inch] journal No. 5, 0.0017-0.0035 inch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Harmonic Balancer Crankshaft Pulley > Component Information > Service and Repair
Harmonic Balancer - Crankshaft Pulley: Service and Repair
CRANKSHAFT BALANCER AND HUB
Tool Required, or equivalent: J39046 Crankshaft Hub Remover/Installer
5.7L Shown 4.3L Similar
REMOVAL
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Harmonic Balancer Crankshaft Pulley > Component Information > Service and Repair > Page 2026
1. Raise and suitably support the vehicle. 2. Remove the accessory drive belt. Remove the
crankshaft balancer bolts. 3. Remove the crankshaft balancer. 4. Match mark the crankshaft hub to
the engine front cover. 5. Do not crank the engine over after match marking the crankshaft hub and
the engine front cover. Rotating the crankshaft will cause misalignment
of the crankshaft balancer, to the crankshaft, possibly resulting in engine imbalance.
6. Remove the crankshaft hub bolt and the crankshaft washer. 7. Remove the crankshaft hub using
the Crankshaft Hub Remover/Installer.
INSTALLATION
1. Install the crankshaft hub using the Crankshaft Hub Remover/Installer. 2. If the engine should
accidentally be cranked over after match marking the hub and the engine front cover, install the
crankshaft hub as follows:
a. Set the number 1 piston to the top dead center. b. While viewing the crankshaft from the front.
Verify that the keyway of the reluctor ring is properly orientated with the key of the crankshaft.
Also verify that the ring is completely seated against the crankshaft sprocket.
c. Install the crankshaft hub with the cast arrow on the hub in the 12 o'clock position.
3. Install the crankshaft hub washer and the bolt. Tighten the crankshaft balancer hub bolt to 100
Nm (74 ft. lbs.).
CAUTION: If the balancer is replaced, a new balance weight of the same size must be installed on
the new balancer in the same hole locations as the old balancer.
4. Install the crankshaft balancer. 5. Install the crankshaft balancer bolts. Tighten the crankshaft
balancer bolt to 85 Nm (63 ft. lbs.). 6. Install the accessory drive belt. 7. Lower the vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston, Engine >
Component Information > Specifications
Piston: Specifications
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Piston Clearance .................................................................................................................................
............................................................ 0.0007-0.0027 Piston Pin Diameter [01] .................................
................................................................................................................................................
0.9270-0.9271 Piston Pin To Piston Clearance ...................................................................................
.................................................................................... 0.0004-0.0010 Piston Ring End Gap [02]
Comp. ..................................................................................................................................................
..................................................................... 0.035 Oil ........................................................................
.....................................................................................................................................................
0.065
Piston Ring Side Clearance
Comp. ..................................................................................................................................................
....................................................... 0.0012-0.0042 Oil ........................................................................
...........................................................................................................................................
0.002-0.008
[01] Pistons & pins are matched set & should be replaced as an assembly. [02] Maximum.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston, Engine >
Component Information > Service and Repair > Oversize Availability
Piston: Service and Repair Oversize Availability
Pistons are available in standard and oversizes of .010 and .030 inch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston, Engine >
Component Information > Service and Repair > Oversize Availability > Page 2032
Piston: Service and Repair Pistons & Rods Assemble
Fig. 11 Piston & Rod Assembly
Assemble pistons to connecting rods as shown in Fig. 11 Upon installation, measure the
connecting rod side clearance using a suitable feeler gauge. Refer to SPECIFICATIONS/ENGINE
REBUILDING
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston, Engine >
Component Information > Service and Repair > Oversize Availability > Page 2033
SPECIFICATIONS for connecting rod side clearance.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston Pin, Engine >
Component Information > Specifications
Piston Pin: Specifications
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Piston Clearance .................................................................................................................................
............................................................ 0.0007-0.0027 Piston Pin Diameter [01] .................................
................................................................................................................................................
0.9270-0.9271 Piston Pin To Piston Clearance ...................................................................................
.................................................................................... 0.0004-0.0010 Piston Ring End Gap [02]
Comp. ..................................................................................................................................................
..................................................................... 0.035 Oil ........................................................................
.....................................................................................................................................................
0.065
Piston Ring Side Clearance
Comp. ..................................................................................................................................................
....................................................... 0.0012-0.0042 Oil ........................................................................
...........................................................................................................................................
0.002-0.008
[01] Pistons & pins are matched set & should be replaced as an assembly. [02] Maximum.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston Ring, Engine >
Component Information > Specifications
Piston Ring: Specifications
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Piston Clearance .................................................................................................................................
............................................................ 0.0007-0.0027 Piston Pin Diameter [01] .................................
................................................................................................................................................
0.9270-0.9271 Piston Pin To Piston Clearance ...................................................................................
.................................................................................... 0.0004-0.0010 Piston Ring End Gap [02]
Comp. ..................................................................................................................................................
..................................................................... 0.035 Oil ........................................................................
.....................................................................................................................................................
0.065
Piston Ring Side Clearance
Comp. ..................................................................................................................................................
....................................................... 0.0012-0.0042 Oil ........................................................................
...........................................................................................................................................
0.002-0.008
[01] Pistons & pins are matched set & should be replaced as an assembly. [02] Maximum.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Block Assembly > Piston Ring, Engine >
Component Information > Specifications > Page 2040
Piston Ring: Service and Repair
Piston rings are available in standard and oversizes of .030 inch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve Clearance >
System Information > Specifications
Valve Clearance: Specifications
VALVE LASH
Turn rocker arm stud nut until all lash is eliminated (zero lash), then tighten nut additional turn in
1/4 turn increments.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve Clearance >
System Information > Specifications > Page 2045
Valve Clearance: Adjustments
Fig. 5 Valve Lash Adjustment
Adjust valves, Fig.5, with engine at normal operating temperature. Rotate engine until No. 1
cylinder is in position to fire. Adjust exhaust valves 1-3-4-8 and intake valves 1-2-5-7. Crank engine
one complete revolution, then adjust exhaust valves 2-5-6-7 and intake vales 3-4-6-8.
On all engines, the following procedure, performed with the engine running, should only be
performed if readjustment is required.
1. After engine has been warmed up to normal operating temperature, remove valve cover and
install a new valve cover gasket. 2. With engine running at idle speed, back off valve rocker arm
nut until rocker arm starts to clatter. 3. Turn rocker arm nut down slowly until clatter just stops. This
is the zero lash position. 4. Turn nut down 1/4 additional turn and pause 10 seconds until engine
runs smoothly. Repeat additional 1/4 turns, pausing 10 seconds each time,
until nut has been turned down the number of turns listed in "Valve Clearance Specifications chart
from the zero lash position. This preload adjustment must be done slowly to allow lifter to adjust
itself to prevent the possibility of interference between valve head and top of piston, which might
result in internal damage and/or bent push rods. Noisy lifters should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Fuel Pressure Release
> System Information > Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Rocker Arm Assembly
> Component Information > Adjustments
Rocker Arm Assembly: Adjustments
Fig. 5 Valve Lash Adjustment
Adjust valves, Fig.5, with engine at normal operating temperature. Rotate engine until No. 1
cylinder is in position to fire. Adjust exhaust valves 1-3-4-8 and intake valves 1-2-5-7. Crank engine
one complete revolution, then adjust exhaust valves 2-5-6-7 and intake vales 3-4-6-8.
On all engines, the following procedure, performed with the engine running, should only be
performed if readjustment is required.
1. After engine has been warmed up to normal operating temperature, remove valve cover and
install a new valve cover gasket. 2. With engine running at idle speed, back off valve rocker arm
nut until rocker arm starts to clatter. 3. Turn rocker arm nut down slowly until clatter just stops. This
is the zero lash position. 4. Turn nut down 1/4 additional turn and pause 10 seconds until engine
runs smoothly. Repeat additional 1/4 turns, pausing 10 seconds each time,
until nut has been turned down the number of turns listed in "Valve Clearance Specifications chart
from the zero lash position. This preload adjustment must be done slowly to allow lifter to adjust
itself to prevent the possibility of interference between valve head and top of piston, which might
result in internal damage and/or bent push rods. Noisy lifters should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Rocker Arm Assembly
> Component Information > Service and Repair > Rocker Arm
Rocker Arm Assembly: Service and Repair Rocker Arm
When replacing rocker arms or rocker arm balls, bearing surfaces of rocker arms and balls should
be coated with pre-lube part No. 3755008 or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Rocker Arm Assembly
> Component Information > Service and Repair > Rocker Arm > Page 2054
Rocker Arm Assembly: Service and Repair Rocker Arm Studs Replace
Fig. 6 Rocker Arm Stud Removal
Fig. 7 Rocker Arm Stud Installation
If studs are loose in cylinder head, .003 inch or .013 inch oversize studs may be installed after
reaming holes with a proper size reamer.
1. Remove old stud by placing a suitable spacer, Fig.6. over stud. Install nut and flat washer and
remove stud by turning nut. 2. Ream hole for oversize stud. 3. Coat press-fit area of stud with rear
axle lube. Then install new stud, Fig.7. If tool shown is used, it should bottom on the head.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve Guide >
Component Information > Specifications
Valve Guide: Specifications
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Valve Guides
Stem To Guide Clearance
Intake ...................................................................................................................................................
................................................. 0.0009-0.0037 Exhaust .....................................................................
............................................................................................................................ 0.0009-0.0047
Valve Seats
Seat Angle ...........................................................................................................................................
................................................................... 46deg. Seat Width
Intake ...................................................................................................................................................
..................................................... 0.030-0.065 Exhaust .....................................................................
................................................................................................................................ 0.060-0.098
Runout .................................................................................................................................................
.......................................................................... 0.002
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve Guide >
Component Information > Specifications > Page 2058
Valve Guide: Service and Repair
On all engines valves operate in guide holes bored in the head. If clearance becomes excessive,
use the next oversize valve and ream the bore to fit. Valves with oversize stems are available in
.003, .015 and .030 inch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve Seat >
Component Information > Specifications
Valve Seat: Specifications
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Valve Guides
Stem To Guide Clearance
Intake ...................................................................................................................................................
................................................. 0.0009-0.0037 Exhaust .....................................................................
............................................................................................................................ 0.0009-0.0047
Valve Seats
Seat Angle ...........................................................................................................................................
................................................................... 46deg. Seat Width
Intake ...................................................................................................................................................
..................................................... 0.030-0.065 Exhaust .....................................................................
................................................................................................................................ 0.060-0.098
Runout .................................................................................................................................................
.......................................................................... 0.002
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve Spring >
Component Information > Specifications
Valve Spring: Specifications
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Free Length .........................................................................................................................................
............................................................................ 2.02 Installed Height ...............................................
..............................................................................................................................................................
.... 1.7 Seated Pressure Pounds @ Inches .........................................................................................
........................................................................... 76-84 @ 1.70 Comp. Pressure Pounds @ Inches ..
..............................................................................................................................................................
187-203 @ 1.27
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve, Intake/Exhaust
> Component Information > Specifications > Valve Lift Specifications
Valve: Specifications Valve Lift Specifications
Int. ........................................................................................................................................................
.......................................................................... .418 Exh. ..................................................................
..............................................................................................................................................................
. .430
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve, Intake/Exhaust
> Component Information > Specifications > Valve Lift Specifications > Page 2069
Valve: Specifications Valve Clearance Specifications
Valve Lash
1 Turn ..................................................................................................................................................
............................................................................. [1]
[1] Turn rocker arm stud nut until all lash is eliminated (zero lash), then tighten nut additional turn in
1/4 turn increments. Refer to Valve Adjustment.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve, Intake/Exhaust
> Component Information > Specifications > Page 2070
Valve: Locations
FRONT TO REAR All.................E-I-I-E-E-I-I-E
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Cylinder Head Assembly > Valve, Intake/Exhaust
> Component Information > Specifications > Page 2071
Valve: Service and Repair
Engine Liter/VIN ..................................................................................................................................
.................................................................... 5.7L/P
All Measurements Given In Inches Unless Otherwise Specified
Valve Lash
Intake ...................................................................................................................................................
....................................................................... [05] Exhaust .................................................................
...................................................................................................................................................... [05]
Face Angle ..........................................................................................................................................
......................................................................... 45deg. Margin ............................................................
..............................................................................................................................................................
.. [01]
[01] Minimum. [05] Zero lash plus or minus 1 1/4 turns.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Technical Service Bulletins > Engine - Drive Belt Misalignment Diagnostics
Drive Belt: Technical Service Bulletins Engine - Drive Belt Misalignment Diagnostics
INFORMATION
Bulletin No.: 08-06-01-008A
Date: July 27, 2009
Subject: Diagnosing Accessory Drive Belt / Serpentine Belt Noise and Availability and Use of
Kent-Moore EN-49228 Laser Alignment Tool - Drive Belt
Models:
2010 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2,
H3 Vehicles 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add a model year and update the Tool Information.
Please discard Corporate Bulletin Number 08-06-01-008 (Section 06 - Engine).
Background
Several aftermarket companies offer laser alignment tools for accessory drive systems that can be
very helpful in eliminating drive belt noise as a result of misaligned pulleys. Typically pricing ranges
from $160 - $200.
EN-49228 Laser Alignment Tool - Drive Belt
The GM Tool program has now made available a competitive, simple to use and time-saving laser
tool to assist in achieving precise alignment of the drive belt pulleys. This optional tool removes the
guesswork from proper pulley alignment and may serve to reduce comebacks from:
- Drive Belt Noise
- Accelerated Drive Belt Wear
- Drive Belt Slippage
Instructions
The instructions below are specific only to the truck Gen IV V-8 family of engines. These
instructions are only for illustrative purposes to show how the tool may be used. Universal
instructions are included in the box with the Laser Alignment Tool - Drive Belt.
Caution
- Do not look directly into the beam projected from the laser.
- Use caution when shining the laser on highly polished or reflective surfaces. Laser safety glasses
help reduce laser beam glare in many circumstances.
- Always use laser safety glasses when using the laser. Laser safety glasses are not designed to
protect eyes from direct laser exposure.
1. Observe and mark the serpentine belt orientation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Technical Service Bulletins > Engine - Drive Belt Misalignment Diagnostics > Page
2077
2. Remove the serpentine belt from the accessory drive system.
3. Install the tool onto the power steering pulley. Position the legs of the tool into the outer grooves
of the pulley, farthest from the front of the
engine.
4. Install the retaining cord around the pulley and to the legs of the tool.
5. Put on the laser safety glasses provided with the tool. 6. Depress the switch on the rear of the
tool to activate the light beam. 7. Rotate the power steering pulley as required to project the light
beam onto the crankshaft balancer pulley grooves. 8. Inspect for proper power steering pulley
alignment.
- If the laser beam projects onto the second rib or raised area (1), the pulleys are aligned properly.
- If the laser beam projects more than one-quarter rib 0.9 mm (0.035 in) mis-alignment, adjust the
position of the power steering pulley as required.
- Refer to SI for Power Steering Pulley Removal and Installation procedures.
9. Install the serpentine belt to the accessory drive system in the original orientation.
10. Operate the vehicle and verify that the belt noise concern is no longer present.
Tool Information
Please visit the GM service tool website for pricing information or to place your order for this tool.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Technical Service Bulletins > Engine - Drive Belt Misalignment Diagnostics > Page
2078
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Technical Service Bulletins > Engine - Drive Belt Misalignment Diagnostics > Page
2079
Drive Belt: Technical Service Bulletins Engine - Serpentine Drive Belt Wear Information
Bulletin No.: 04-06-01-013
Date: April 29, 2004
INFORMATION
Subject: Information on Serpentine Belt Wear
Models: 2004 and Prior Passenger Cars and Trucks 2003-2004 and Prior HUMMER H2
All current GM vehicles designed and manufactured in North America were assembled with
serpentine belts that are made with an EPDM material and should last the life of the vehicle. It is
extremely rare to observe any cracks in EPDM belts and it is not expected that they will require
maintenance before 10 years or 240,000 km (150,000 mi) of use.
Older style belts, which were manufactured with a chloroprene compound, may exhibit cracks
depending on age. However, the onset of cracking typically signals that the belt is only about
halfway through its usable life.
A good rule of thumb for chloroprene-based belts is that if cracks are observed 3 mm (1/8 in) apart,
ALL AROUND THE BELT, the belt may be reaching the end of its serviceable life and should be
considered a candidate for changing. Small cracks spaced at greater intervals should not be
considered as indicative that the belt needs changing.
Any belt that exhibits chunking should be replaced.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Specifications > Serpentine Belt Tension Specification
Drive Belt: Specifications Serpentine Belt Tension Specification
Engines equipped with serpentine belts have an automatic tensioner. No adjustment of this is
necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Specifications > Serpentine Belt Tension Specification > Page 2082
Drive Belt: Specifications Air Conditioning Belt Tension Specification
New .....................................................................................................................................................
............................................................... 105-125 Lbs
Used ....................................................................................................................................................
............................................................... 105-125 Lbs
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt > Component Information > Specifications > Page 2083
Drive Belt: Service and Repair
Fig. 16 Serpentine Drive Belt Routing
SERPENTINE DRIVE BELT BELT ROUTING
Refer to Fig.16. for serpentine belt routing diagrams.
BELT REPLACEMENT
1. Disconnect battery ground cable. 2. On models with mechanical cooling fan, proceed as follows:
a. Rotate mechanical cooling fan tensioner pulley clockwise using a suitable 13 mm wrench while
sliding belt from tensioner pulley. b. Remove fan belt from pulleys. c. Remove radiator outlet nuts at
air conditioning compressor.
3. On all models, rotate tensioner pulley clockwise using a suitable 9/16 offset wrench while sliding
belt from tensioner, then remove serpentine
drive belt.
4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Drive Belt Tensioner > Component Information > Service and Repair
Drive Belt Tensioner: Service and Repair
1. Disconnect battery ground cable. 2. Remove serpentine belt as outlined under Drive belts
Service and Repair. 3. Remove belt tensioner attaching bolt, then belt tensioner. 4. Reverse
procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Engine Mount > Component Information > Service and Repair
Engine Mount: Service and Repair
Fig. 1 Engine & Transmission Mounting
1. Remove mount retaining bolt from below frame mounting bracket, Fig. 1. 2. Raise front of engine
and remove mount to engine bolts and mount.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Drive Belts, Mounts, Brackets and Accessories >
Engine Mount > Component Information > Service and Repair > Page 2090
3. On all models, raise engine only enough to provide sufficient clearance for mount removal.
Check for interference between rear of engine
and cowl panel which could result in distributor damage.
4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Engine Oil Pressure >
Component Information > Specifications
Engine Oil Pressure: Specifications
Normal Oil Pressure, psi ................................................. Minimum w/ engine hot, 6 psi. @ 1000
RPM; 18 psi. @ 2000 RPM; 24 psi. @ 4000 RPM.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Engine Oil > Component
Information > Technical Service Bulletins > Engine - GM dexos 1 and dexos 2(R) Oil Specifications
Engine Oil: Technical Service Bulletins Engine - GM dexos 1 and dexos 2(R) Oil Specifications
INFORMATION
Bulletin No.: 11-00-90-001
Date: March 14, 2011
Subject: Global Information for GM dexos1(TM) and GM dexos2(TM) Engine Oil Specifications for
Spark Ignited and Diesel Engines, Available Licensed Brands, and Service Fill for Adding or
Complete Oil Change
Models:
2012 and Prior GM Passenger Cars and Trucks Excluding All Vehicles Equipped with
Duramax(TM) Diesel Engines
GM dexos 1(TM) Information Center Website
Refer to the following General Motors website for dexos 1(TM) information about the different
licensed brands that are currently available: http://www.gmdexos.com
GM dexos 1(TM) Engine Oil Trademark and Icons
The dexos(TM) specification and trademarks are exclusive to General Motors, LLC.
Only those oils displaying the dexos‹›(TM) trademark and icon on the front label meet the
demanding performance requirements and stringent quality standards set forth in the dexos‹›(TM)
specification.
Look on the front label for any of the logos shown above to identify an authorized, licensed dexos
1(TM) engine oil.
GM dexos 1(TM) Engine Oil Specification
Important General Motors dexos 1(TM) engine oil specification replaces the previous General
Motors specifications GM6094M, GM4718M and GM-LL-A-025 for most GM gasoline engines. The
oil specified for use in GM passenger cars and trucks, PRIOR to the 2011 model year remains
acceptable for those previous vehicles. However, dexos 1(TM) is backward compatible and can be
used in those older vehicles.
In North America, starting with the 2011 model year, GM introduced dexos 1(TM) certified engine
oil as a factory fill and service fill for gasoline engines. The reasons for the new engine oil
specification are as follows:
- To meet environmental goals such as increasing fuel efficiency and reducing engine emissions.
- To promote long engine life.
- To minimize the number of engine oil changes in order to help meet the goal of lessening the
industry's overall dependence on crude oil.
dexos 1(TM) is a GM-developed engine oil specification that has been designed to provide the
following benefits:
- Further improve fuel economy, to meet future corporate average fuel economy (CAFE)
requirements and fuel economy retention by allowing the oil to maintain its fuel economy benefits
throughout the life of the oil.
- More robust formulations for added engine protection and aeration performance.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Engine Oil > Component
Information > Technical Service Bulletins > Engine - GM dexos 1 and dexos 2(R) Oil Specifications > Page 2099
- Support the GM Oil Life System, thereby minimizing the replacement of engine oil, before its life
has been depleted.
- Reduce the duplication of requirements for a large number of internal GM engine oil
specifications.
International Lubricants Standardization and Approval Committee (ILSAC)
GF-5 Standard
In addition to GM dexos 1(TM), a new International Lubricants Standardization and Approval
Committee (ILSAC) standard called GF-5, was introduced in October 2010.
- There will be a corresponding API category, called: SN Resource Conserving. The current GF-4
standard was put in place in 2004 and will become obsolete in October 2011. Similar to dexos
1(TM), the GF-5 standard will use a new fuel economy test, Sequence VID, which demands a
statistically significant increase in fuel economy versus the Sequence VIB test that was used for
GF-4.
- It is expected that all dexos 1(TM) approved oils will be capable of meeting the GF-5 standard.
However, not all GF-5 engine oils will be capable of meeting the dexos 1(TM) specification.
- Like dexos(TM), the new ILSAC GF-5 standard will call for more sophisticated additives. The API
will begin licensing marketers during October 2010, to produce and distribute GF-5 certified
products, which are expected to include SAE 0W-20, 0W-30, 5W-20, 5W-30 and 10W-30 oils.
Corporate Average Fuel Economy (CAFE) Requirements Effect on Fuel Economy
Since CAFE standards were first introduced in 1974, the fuel economy of cars has more than
doubled, while the fuel economy of light trucks has increased by more than 50 percent. Proposed
CAFE standards call for a continuation of increased fuel economy in new cars and trucks. To meet
these future requirements, all aspects of vehicle operation are being looked at more critically than
ever before.
New technology being introduced in GM vehicles designed to increase vehicle efficiency and fuel
economy include direct injection, cam phasing, turbocharging and active fuel management (AFM).
The demands of these new technologies on engine oil also are taken into consideration when
determining new oil specifications. AFM for example can help to achieve improved fuel economy.
However alternately deactivating and activating the cylinders by not allowing the intake and
exhaust valves to open contributes to additional stress on the engine oil.
Another industry trend for meeting tough fuel economy mandates has been a shift toward lower
viscosity oils.
dexos 1(TM) will eventually be offered in several viscosity grades in accordance with engine needs:
SAE 0W-20, 5W-20, 0W-30 and 5W-30.
Using the right viscosity grade oil is critical for proper engine performance. Always refer to the
Maintenance section of a vehicle Owner Manual for the proper viscosity grade for the engine being
serviced.
GM Oil Life System in Conjunction With dexos (TM) Supports Extended Oil Change Intervals
To help conserve oil while maintaining engine protection, many GM vehicles are equipped with the
GM Oil Life System. This system can provide oil change intervals that exceed the traditional 3,000
mile (4,830 km) recommendation.
The dexos (TM) specification, with its requirements for improved oil robustness, compliments the
GM Oil Life System by supporting extended oil change intervals over the lifetime of a vehicle.
If all GM customers with GM Oil Life System equipped vehicles would use the system as intended,
GM estimates that more than 100 million gallons of oil could be saved annually.
GM dexos 2(TM) Information Center Website
Refer to the following General Motors website for dexos 2(TM) information about the different
licensed brands that are currently available: http://www.gmdexos.com
GM dexos 2(TM) Engine Oil Trademark and Icons
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Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Engine Oil > Component
Information > Technical Service Bulletins > Engine - GM dexos 1 and dexos 2(R) Oil Specifications > Page 2100
The dexos (TM) specification and trademarks are exclusive to General Motors, LLC.
Only those oils displaying the dexos (TM) trademark and icon on the front label meet the
demanding performance requirements and stringent quality standards set forth in the dexos
(TM)specification.
Look on the front label for any of the logos shown above to identify an authorized, licensed dexos
2(TM) engine oil.
GM dexos 2(TM) Engine Oil Specification
- dexos 2(TM) is approved and recommended by GM for use in Europe starting in model year 2010
vehicles, regardless of where the vehicle was manufactured.
- dexos 2(TM) is the recommended service fill oil for European gasoline engines.
Important The Duramax(TM) diesel engine is the exception and requires lubricants meeting
specification CJ-4.
- dexos 2(TM) is the recommended service fill oil for European light-duty diesel engines and
replaces GM-LL-B-025 and GM-LL-A-025.
- dexos 2(TM) protects diesel engines from harmful soot deposits and is designed with limits on
certain chemical components to prolong catalyst life and protect expensive emission reduction
systems. It is a robust oil, resisting degradation between oil changes and maintaining optimum
performance longer.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Engine Oil > Component
Information > Specifications > Capacity Specifications
Engine Oil: Capacity Specifications
Fluid Type ............................................................................................................................................
.................................................. API service SH/SG
Capacity
Without filter change ............................................................................................................................
................................................. 3.8 liters (4.0 qt) With filter change ....................................................
.............................................................................................................................. 4.7 liters (5.0 qt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Filter, Engine >
Component Information > Technical Service Bulletins > Engine - Noise/Damage Oil Filter Application Importance
Oil Filter: Technical Service Bulletins Engine - Noise/Damage Oil Filter Application Importance
INFORMATION
Bulletin No.: 07-06-01-016B
Date: July 27, 2009
Subject: Information on Internal Engine Noise or Damage After Oil Filter Replacement
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
Supercede: This bulletin is being updated to add model years. Please discard Corporate Bulletin
Number 07-06-01-016A (Section 06 - Engine/Propulsion System).
Important Engine damage that is the result of an incorrect or improperly installed engine oil filter is
not a warrantable claim. The best way to avoid oil filter quality concerns is to purchase ACDelco(R)
oil filters directly from GMSPO.
Oil filter misapplication may cause abnormal engine noise or internal damage. Always utilize the
most recent parts information to ensure the correct part number filter is installed when replacing oil
filters. Do not rely on physical dimensions alone. Counterfeit copies of name brand parts have been
discovered in some aftermarket parts systems. Always ensure the parts you install are from a
trusted source. Improper oil filter installation may result in catastrophic engine damage.
Refer to the appropriate Service Information (SI) installation instructions when replacing any oil
filter and pay particular attention to procedures for proper cartridge filter element alignment. If the
diagnostics in SI (Engine Mechanical) lead to the oil filter as the cause of the internal engine noise
or damage, dealers should submit a field product report. Refer to Corporate Bulletin Number
02-00-89-002I (Information for Dealers on How to Submit a Field Product Report).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Level Warning Indicator >
Component Information > Description and Operation
Oil Level Warning Indicator: Description and Operation
DESCRIPTION
This lamp illuminates to warn the driver that the engine oil level is low. When the ignition switch is
first moved to Run, the oil level indicator lights for about 1 1/2 seconds as a bulb check. The oil
level detection circuit has two internal timers. The first timer records the amount of time the ignition
has been Off. The second timer records the amount of time the ignition has been On before the
ignition was shut Off. The instrument cluster uses this information to determine if the engine has
been sitting long enough for the oil to have returned to the oil pan.
OPERATION
The oil level monitoring circuits will check the oil level switch under the following conditions:
1. Ignition has been turned Off for more than 30 minutes. 2. Ignition has been Off for at least three
minutes after ignition has been On for at least 12 minutes.
If the oil level is low (oil level switch open), the "Check Oil" indicator will be turned On for the
remainder of the ignition cycle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Level Warning Indicator >
Component Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator Inoperative W/Oil Level Low
Fig. 99 Chart 8: Low Oil Level Indicator Inoperative W/Oil Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Level Warning Indicator >
Component Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low > Page 2112
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator On w/Oil Level OK
Fig. 98 Chart 7: Low Oil Level Indicator On W/Oil Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Level Sensor >
Component Information > Locations
Engine, Left Side Lower
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Level Sensor >
Component Information > Diagrams > Diagram Information and Instructions
Oil Level Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Component Information > Diagrams > Diagram Information and Instructions > Page 2118
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Component Information > Diagrams > Diagram Information and Instructions > Page 2119
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Component Information > Diagrams > Diagram Information and Instructions > Page 2120
Fig.1-Symbols (Part 1 Of 3)
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Component Information > Diagrams > Diagram Information and Instructions > Page 2121
Fig.2-Symbols (Part 2 Of 3)
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Component Information > Diagrams > Diagram Information and Instructions > Page 2122
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Component Information > Diagrams > Diagram Information and Instructions > Page 2123
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Component Information > Diagrams > Diagram Information and Instructions > Page 2124
Oil Level Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Component Information > Diagrams > Diagram Information and Instructions > Page 2125
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Component Information > Diagrams > Diagram Information and Instructions > Page 2126
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Component Information > Diagrams > Diagram Information and Instructions > Page 2127
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Component Information > Diagrams > Diagram Information and Instructions > Page 2128
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pan, Engine >
Component Information > Service and Repair
Oil Pan: Service and Repair
Fig. 14 Oil Pan & Gasket Assembly
1. Disconnect battery ground cable, then remove air cleaner, resonator and air intake duct. 2.
Remove radiator upper fan shroud if equipped with a mechanical fan. 2. Disconnect windshield
wiper motor electrical connector. 3. Raise and support vehicle, then drain engine oil. 4. Disconnect
oil level sensor connector, then remove oil level sensor. 5. Remove warm up three-way catalytic
converters from exhaust manifolds, then catalytic converter support-to-transmission bolts/screws
and
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washers.
6. Remove engine oil filter adapter, then disconnect transmission fluid cooler lines from clip at oil
pan. 7. Remove starter, then converter cover bolt/screws and cover. 8. Rotate crankshaft until
arrow on crankshaft balancer is pointing straight down (six o'clock). 9. Remove engine mount
through-bolts/screws and nuts, then raise engine with jacking fixture.
10. Remove oil pan bolts, screws, studs & nuts, then oil pan, reinforcements and gaskets Fig. 14
11. Reverse procedure to install. Apply a small quantity of sealer part No. 1052914 or equivalent to
front cover and engine block junction and rear
seal retainer and engine block junction.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Gauge >
Component Information > Description and Operation
Oil Pressure Gauge: Description and Operation
DESCRIPTION
This oil pressure indicating system incorporates an instrument voltage regulator, electrical oil
pressure gauge and a sending unit which are connected in series. The sending unit consists of a
diaphragm, contact and a variable resistor.
OPERATION
As oil pressure increases or decreases, the diaphragm actuated the contact on the variable
resistor, in turn controlling current flow through the gauge. When oil pressure is low, the resistance
of the variable resistor is high, restricting current flow to the gauge, in turn indicating low oil
pressure. As oil pressure increases, the resistance of the variable resistor is lowered, permitting an
increased current flow to the gauge, resulting in an increased gauge reading.
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Oil Pressure Gauge: Service and Repair
Disconnect the oil pressure gauge lead from the sending unit, connect a 12 volt test lamp between
the gauge lead and the ground and turn ignition on. If test lamp flashes, the instrument voltage
regulator is functioning properly and the gauge circuit is not broken. If the test lamp remains lit, the
instrument voltage regulator is defective and must be replaced. If the test lamp does not light,
check the instrument voltage regulator for proper ground or an open circuit. Also, check for an open
in the instrument voltage regulator to oil pressure gauge wire or in the gauge itself. If test lamp
flashes and gauge is not accurate, the gauge may be out of calibration, requiring replacement.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Sender >
Component Information > Locations
Rear Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Specifications
Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Locations > Fuel Pump/Engine Oil Pressure Indicator Switch
Rear Of Engine
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Fuel Pump) > Component Information > Locations > Fuel Pump/Engine Oil Pressure Indicator Switch > Page 2165
Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions
Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2173
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2179
1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2194
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2195
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2196
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2197
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2198
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2199
Fuel Pump Switch/Engine Oil Pressure Gage Sensor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2200
Fuel Pump Relay Circuit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Page 2201
Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pressure Switch (For
Fuel Pump) > Component Information > Diagrams > Page 2202
Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Pump, Engine > Engine
Oil Pressure > Component Information > Specifications
Engine Oil Pressure: Specifications
Normal Oil Pressure, psi ................................................. Minimum w/ engine hot, 6 psi. @ 1000
RPM; 18 psi. @ 2000 RPM; 24 psi. @ 4000 RPM.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Engine Lubrication > Oil Level Sensor <--> [Oil
Temperature Gauge] > Component Information > Testing and Inspection
Oil Level Sensor: Testing and Inspection
Check for a defective wire inside the insulation which could cause system malfunction but prove
"GOOD" in a continuity/voltage check with the system disconnected. These circuits may be
intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage
drop with the system operational.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Intake Manifold > Component Information >
Technical Service Bulletins > Engine - Intake Manifold Inspection/Replacement
Intake Manifold: Technical Service Bulletins Engine - Intake Manifold Inspection/Replacement
INFORMATION
Bulletin No.: 00-06-01-026C
Date: February 03, 2010
Subject: Intake Manifold Inspection/Replacement After Severe Internal Engine Damage
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to include additional model years. Please discard
Corporate Bulletin Number 00-06-01-026B (Section 06 - Engine).
When replacing an engine due to internal damage, extreme care should be taken when transferring
the intake manifold to the new Goodwrench service engine long block. Internal damage may result
in the potential discharge of internal engine component debris in the intake manifold via broken
pistons and/or bent, broken, or missing intake valves. After removing the intake manifold from the
engine, the technician should carefully inspect all of the cylinder head intake ports to see if the
valve heads are still present and not bent. Usually when the valve heads are missing or sufficiently
bent, internal engine component debris will be present to varying degrees in the intake port of the
cylinder head. If this debris is present in any of the cylinder head intake ports, the intake manifold
should be replaced. This replacement is required due to the complex inlet runner and plenum
configuration of most of the intake manifolds, making thorough and complete component cleaning
difficult and nearly impossible to verify complete removal of debris. Re-installation of an intake
manifold removed from an engine with deposits of internal engine component debris may result in
the ingestion of any remaining debris into the new Goodwrench service engine. This may cause
damage or potential failure of the new service engine.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Intake Manifold > Component Information >
Technical Service Bulletins > Engine - Intake Manifold Inspection/Replacement > Page 2214
Intake Manifold: Technical Service Bulletins Engine - Use of Wacker RTV Sealant for Intake
Manifold
File In Section: 6 - Engine
Bulletin No.: 67-61-17A
Date: August, 1996
Subject: Use of Wacker T-330 RTV Sealant (Pronounced Vaucker T)
Models: 1990-96 Buick Road master, Estate Wagon 1990-96 Cadillac Fleetwood 1990-96
Chevrolet Camaro, Caprice, Corvette, Impala SS 1990-92 Oldsmobile Custom Cruiser 1990-96
Pontiac Firebird with 4.3L, 5.7L Engine (VINs W, P, 5, 8 - RPOs L99, L98, LT1, LT4) 1990-96
Chevrolet and GMC Light and Medium Duty Trucks with 4.3L, 5.0L, 5.7L, 6.0L, 7.0L, 7.4L Engines
(VINs W, Z, E H, K, M, N, P, R - RPOs L35, LB4, L03, L05, LS0, LR0, L19, L30, L31)
This bulletin is being revised to add further Chevrolet models. Please discard Corporate Bulletin
Number 67-61-17 (Section 6 - Engine).
When installing the intake manifold, use a 5 mm (1/4 in.) thick bead of Wacker T-330 RTV, P/N
12346192, on the front and rear sealing areas between
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Intake Manifold > Component Information >
Technical Service Bulletins > Engine - Intake Manifold Inspection/Replacement > Page 2215
the engine block and intake manifold. See Figures 1 and 2. Wacker T-330 RTV has improved
adhesive abilities, is oxygen sensor safe, and is noncorrosive to ferrous metals. Wacker T-330 RW
cannot be used in coolant sealing surface areas.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Intake Manifold > Component Information >
Specifications > Intake Manifold Torque and Sequence
Intake Manifold: Specifications Intake Manifold Torque and Sequence
INTAKE MANIFOLD TORQUE SPECIFICATION AND SEQUENCE
Intake Manifold Bolt Tightening Sequence
Intake Manifold Bolt/Screw and Stud
First Pass .............................................................................................................................................
.......................................................... 8 Nm (71 lb in)
Final Pass ............................................................................................................................................
......................................................... 48 Nm (35 lb ft)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Intake Manifold > Component Information >
Specifications > Page 2218
Intake Manifold: Service and Repair
These engines are equipped with a sequential multi-port fuel injection system. Fuel injector
connectors must be positioned onto the correct fuel injectors or engine performance and exhaust
emissions may be seriously affected. Fuel injector connectors are numbered to match the correct
injector for that cylinder.
1. Disconnect battery ground cable, then drain coolant into suitable container(s). 2. Remove air
cleaner resonator bracket nuts and resonator assembly by loosening clamp at air intake duct and
sliding resonator assembly off studs. 3. Remove throttle body air duct. 4. Disconnect fuel injector
wiring harness connectors. 5. Disconnect left and right wiring harness clips, then position aside. 6.
Remove accelerator control cable bracket bolts/screws and bracket from throttle body. 7. Relieve
fuel system pressure as outlined. 8. Disconnect fuel pipe connectors from fuel rail, then remove
fuel rail bolts/screws. 9. Remove resonator bracket with canister purge solenoid attached.
10. Disconnect fuel pressure regulator vacuum tube, then remove fuel rail from intake manifold and
position aside. 11. Disconnect vacuum and crankcase vent hoses. 12. Remove EGR control valve
relay nut, then control valve relay. 13. Remove EGR valve pipe nuts, bolt/screw, pipe and gasket.
Discard gasket. 14. Disconnect engine wiring harness and remove nuts at left front corner of intake
manifold. 15. Disconnect coolant hoses from throttle body, then remove throttle body bolts/screws,
throttle body and gasket. 16. Remove intake manifold bolts/screws and studs, then intake manifold
and gaskets. Discard gaskets. 17. Reverse procedure to install, noting the following:
a. Ensure surfaces are clean and dry, then apply a 3/16 bead of RTV sealer to front and rear of
engine block. Extend bead approximately 1/2 inch
up each cylinder head.
b. Install manifold and retaining bolts, ensuring areas between case ridges and manifold are
completely sealed.
Intake Manifold Bolt Tightening Sequence
c. Tighten manifold bolts to specifications in sequence shown in Fig. 2.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Lamps and Indicators - Engine > Oil Level
Warning Indicator > Component Information > Description and Operation
Oil Level Warning Indicator: Description and Operation
DESCRIPTION
This lamp illuminates to warn the driver that the engine oil level is low. When the ignition switch is
first moved to Run, the oil level indicator lights for about 1 1/2 seconds as a bulb check. The oil
level detection circuit has two internal timers. The first timer records the amount of time the ignition
has been Off. The second timer records the amount of time the ignition has been On before the
ignition was shut Off. The instrument cluster uses this information to determine if the engine has
been sitting long enough for the oil to have returned to the oil pan.
OPERATION
The oil level monitoring circuits will check the oil level switch under the following conditions:
1. Ignition has been turned Off for more than 30 minutes. 2. Ignition has been Off for at least three
minutes after ignition has been On for at least 12 minutes.
If the oil level is low (oil level switch open), the "Check Oil" indicator will be turned On for the
remainder of the ignition cycle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Lamps and Indicators - Engine > Oil Level
Warning Indicator > Component Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator Inoperative W/Oil Level Low
Fig. 99 Chart 8: Low Oil Level Indicator Inoperative W/Oil Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Lamps and Indicators - Engine > Oil Level
Warning Indicator > Component Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low >
Page 2225
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator On w/Oil Level OK
Fig. 98 Chart 7: Low Oil Level Indicator On W/Oil Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Lamps and Indicators - Engine > Oil Pressure
Gauge > Component Information > Description and Operation
Oil Pressure Gauge: Description and Operation
DESCRIPTION
This oil pressure indicating system incorporates an instrument voltage regulator, electrical oil
pressure gauge and a sending unit which are connected in series. The sending unit consists of a
diaphragm, contact and a variable resistor.
OPERATION
As oil pressure increases or decreases, the diaphragm actuated the contact on the variable
resistor, in turn controlling current flow through the gauge. When oil pressure is low, the resistance
of the variable resistor is high, restricting current flow to the gauge, in turn indicating low oil
pressure. As oil pressure increases, the resistance of the variable resistor is lowered, permitting an
increased current flow to the gauge, resulting in an increased gauge reading.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Lamps and Indicators - Engine > Oil Pressure
Gauge > Component Information > Description and Operation > Page 2229
Oil Pressure Gauge: Service and Repair
Disconnect the oil pressure gauge lead from the sending unit, connect a 12 volt test lamp between
the gauge lead and the ground and turn ignition on. If test lamp flashes, the instrument voltage
regulator is functioning properly and the gauge circuit is not broken. If the test lamp remains lit, the
instrument voltage regulator is defective and must be replaced. If the test lamp does not light,
check the instrument voltage regulator for proper ground or an open circuit. Also, check for an open
in the instrument voltage regulator to oil pressure gauge wire or in the gauge itself. If test lamp
flashes and gauge is not accurate, the gauge may be out of calibration, requiring replacement.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Lamps and Indicators - Engine > Oil Level Sensor
<--> [Oil Temperature Gauge] > Component Information > Testing and Inspection
Oil Level Sensor: Testing and Inspection
Check for a defective wire inside the insulation which could cause system malfunction but prove
"GOOD" in a continuity/voltage check with the system disconnected. These circuits may be
intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage
drop with the system operational.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Seals and Gaskets, Engine > Crankshaft Main
Bearing Seal > Component Information > Service and Repair
Crankshaft Main Bearing Seal: Service and Repair
Fig. 12 Crankshaft Rear Oil Seal Retainer Notch Locations
Fig. 13 Crankshaft Rear Oil Seal Installation
These engines are equipped with a one-piece, lip type seal mounted in a separate seal retainer.
Seal replacement requires removal of the transmission.
1. Raise and support vehicle, then remove transmission and flywheel. 2. Pry seal from retainer,
inserting screwdriver in notches provided in seal retainer, Fig.12. 3. Lubricate inner and outer
diameters of replacement seal with engine oil, then mount seal on tool No. J-35621, or equivalent,
Fig.13. 4. Mount seal installer tool No. J-35621, or equivalent, on rear of crankshaft, tightening
screws snugly to ensure seal will be installed squarely on
crankshaft.
5. Tighten wing nut on tool until it bottoms, then remove tool from crankshaft. 6. Reverse remaining
removal steps to complete installation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Locations
Engine, Left Side Lower
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions
Oil Level Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2243
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2244
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2245
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2246
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2247
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2248
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Level
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 2249
Oil Level Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Sender > Component Information > Locations
Rear Of Engine
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Switch (For Fuel Pump) > Component Information > Specifications
Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
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Rear Of Engine
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2282
Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
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Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2306
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2307
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2308
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2309
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2310
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2311
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2312
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2313
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2314
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2315
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2316
Fuel Pump Switch/Engine Oil Pressure Gage Sensor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 2317
Fuel Pump Relay Circuit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Page 2318
Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Sensors and Switches - Engine > Oil Pressure
Switch (For Fuel Pump) > Component Information > Diagrams > Page 2319
Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Timing Components > Timing Chain > Component
Information > Service and Repair > Interference Engine
Timing Chain: Service and Repair Interference Engine
The OE manufacture does not specify if this engine is an interference engine or not.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Timing Components > Timing Chain > Component
Information > Service and Repair > Interference Engine > Page 2325
Timing Chain: Service and Repair Timing Chain and Sprocket
5.7L Shown 4.3L Similar
1. Remove engine front cover. 2. Remove crankshaft oil slinger. 3. Crank engine until timing marks
on sprockets are in alignment, Fig.9. 4. Remove three camshaft to sprocket bolts. 5. Remove
camshaft sprocket and timing chain together. Sprocket is a light press fit on camshaft for
approximately 1/8 inch. If sprocket does not
come off easily, a light blow with a plastic hammer on lower edge of sprocket should dislodge it.
6. If crankshaft sprocket is to be replaced, remove it with a suitable gear puller. Install new
sprocket, aligning key and keyway. 7. Install chain on camshaft sprocket. Hold sprocket vertical
with chain hanging below and shift around to align timing marks on sprockets. 8. Align dowel in
camshaft with dowel hole in sprocket and install sprocket on camshaft. Do not attempt to drive
sprocket on camshaft as welch plug
at rear of engine can be dislodged.
9. Draw sprocket onto camshaft, using the three mounting bolts. Tighten to specifications.
10. Lubricate timing chain with engine oil and install cover.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Timing Components > Timing Cover > Component
Information > Service and Repair
Timing Cover: Service and Repair
On all engines the cover oil seal may be replaced without taking off the timing gear cover. After
removing the vibration damper, pry out the old seal with a screwdriver. Install the new seal with the
lip or open end toward inside of cover and drive it into position.
1. Remove water pump. 2. Remove crankshaft balancer and hub. 3. Remove distributor. 4.
Remove oil pan and gasket. 5. Remove front cover retaining screws and front cover. 6. Reverse
procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Fuel
Pressure > Diagnostic Connector - Fuel Pump > Component Information > Locations
Diagnostic Connector - Fuel Pump: Locations
The fuel pump test connector is located in the engine compartment near the A/C accumulator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Fuel
Pressure > Fuel Pressure Test Port > Component Information > Locations
Fuel Pressure Test Port
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Fuel
Pressure > Fuel Pressure Test Port > Component Information > Locations > Page 2337
Fuel Pressure Test Port: Service and Repair
Fuel Test Port Valve
CLEAN
^ Area around fuel pressure connection with GM X-3OA or equivalent.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery System / Service and Repair.
3. Fuel pressure connection valve assembly.
INSTALL OR CONNECT
1. Fuel pressure connection valve assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten
seconds. Again turn to "ON" position, and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Air/Fuel Mixture > System Information > Specifications
Air/Fuel Mixture: Specifications
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Air/Fuel Mixture > System Information > Specifications > Page 2341
Air/Fuel Mixture: Adjustments
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Idle
Speed > System Information > Specifications
Idle Speed: Specifications
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Idle
Speed > System Information > Specifications > Page 2345
Idle Speed: Adjustments
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Cleaner Fresh Air Duct/Hose > Component Information > Locations
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > Customer Interest for Air
Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > Customer Interest for Air
Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 2358
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > All Technical Service
Bulletins for Air Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > All Technical Service
Bulletins for Air Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page
2364
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > Page 2365
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > Page 2366
Air Filter Element: Service and Repair
Air Ducting
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Air
Cleaner Housing > Air Filter Element > Component Information > Technical Service Bulletins > Page 2367
REMOVE OR DISCONNECT
1. Loosen wing nuts at front of air cleaner housing. 2. Lift air cleaner lid, Mass Air Flow (MAF)
sensor and resonator as a unit. 3. Remove air filter element.
INSTALL OR CONNECT
1. Install air filter element. 2. Move air cleaner lid, MAF sensor and resonator into place. 3. Tighten
wing nuts. 4. Check clamps at MAF sensor and tighten if necessary. 5. Check joints between duct,
resonators and throttle body for possible air leaks. Repair if necessary.
NOTICE: If the Mass Air Flow (MAF) sensor is installed backwards, the system will go rich. An
arrow cast into the plastic portion of the sensor indicates proper air flow direction. The arrow must
point toward the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Fuel
Filter > Fuel Pressure Release > System Information > Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Firing
Order > Component Information > Specifications > Ignition Firing Order
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Ignition Timing > Number One Cylinder > Component Information > Locations > Number 1 Cylinder Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Ignition Timing > Timing Marks and Indicators > System Information > Locations > Crankshaft Rotation
Timing Marks and Indicators: Locations Crankshaft Rotation
Crankshaft Rotation (Typical Crankshaft Pulley)
Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the
generic image.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Ignition Timing > Timing Marks and Indicators > System Information > Locations > Crankshaft Rotation > Page 2385
Timing Marks and Indicators: Locations Timing Marks
The ignition timing is completely controlled by the Powertrain Control Module (PCM). No timing
reference marks are provided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications
Spark Plug Wire: Specifications
Wire Harness Support Bolt / Screw
............................................................................................................................................................
40 Nm (30 lb ft.)
Wire Harness Support Channel Bolt / Screw (Right)
................................................................................................................................ 12 Nm (106 lb in.)
Wire Harness Support Channel Bolt/Screw (Left)
..................................................................................................................................... 12 Nm (106 lb
ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2389
Spark Plug Wire: Locations
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2390
Spark Plug Harness Routing
The spark plug wires run down both sides of the engine block under the exhaust manifolds.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2391
Spark Plug Wire: Description and Operation
The spark plug wire hamess assemblies use carbon impregnated cord conductors, encased in 8
mm (5 / 16-inch) diameter silicone jackets. The silicone jackets withstand very high temperatures
and also provide excellent insulation for the high voltage of the system. Silicone spark plug boots
form a tight seal to the spark plugs.
The material used to construct spark plug wires is very soft. This wire will withstand more heat and
carry a higher voltage, but chaffing and cutting become easier. The spark plug wires must be
routed correctly to prevent chafing or cutting. When removing a spark plug wire from a spark plug,
twist the boot on the spark plug one-half turn while pulling on the boot.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2392
Spark Plug Wire: Testing and Inspection
Inspect spark plug wires visually first for any cuts, burns, or damage. While engine is running,
inspect for any arcing to ground or other components. Use a spray bottle to lightly coat the spark
plug wires with water while observing idle quality. If idle quality diminishes or engine stalls, spark
plug wires should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2393
Spark Plug Wire: Service and Repair
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2394
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2395
Spark Plug Harness Routing
NOTICE: The boots should be twisted one-half turn while removing. Do not pull on the wire
harnesses to remove them from the spark plugs. Pull on the boots, or use a tool designed for this
purpose.
REMOVE OR DISCONNECT
Numbers included in this procedure refer to caption numbers in the included images.
1. Left bank spark plug wire boots from spark plugs. 2. Left bank spark plug wire harness support
channel bolts / screws (19) and channel. Rear bolt / screw (19) is located behind exhaust manifold
takedown. Loosen this bolt / screw using a 10 mm wrench then slide channel upward to disengage
from bolt / screw (19).
3. Left bank spark plug wire harness from clip (17) located behind air injection reactor (AIR) pump.
4. Right bank spark plug wire boots from spark plugs. 5. Air intake resonator.
With mechanical cooling fan: A. Upper radiator fan shroud, B. Loosen fan pulley nuts. C. Fan belt.
D. Mechanical fan and pulley. E. Mechanical fan pulley bracket nuts and bracket. F. Radiator outlet
pipe nuts from A/C compressor mounting studs.
6. Serpentine drive belt. 7. Raise and suitably support vehicle. 8. Transmission oil cooler line
support bolt / screw from accessory drive bracket. 9. Serpentine drive belt tensioner bolts/screws
and tensioner.
10. A/C compressor attaching bolts/screws
Reposition A/C compressor to provide access to front wire harness support (27).
11. Right wire harness support bolt / screw (28). 12. Right wire harness from support (27). 13. Left
and right bank spark plug wire harnesses (6) from distributor. 14. Left wire harness from clips (17,
20, 21 and 23).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Spark
Plug Wire <--> [Ignition Cable] > Component Information > Specifications > Page 2396
^ Insert screwdriver into tab on top of clip to disengage.
15. Right wire harness from clips (16, 17, and 21).
^ Insert screwdriver into tab on top of clip to disengage.
NOTICE: When replacing spark plug wire harnesses (secondary wiring), route the wire harnesses
correctly and through the proper retainers. Failure to
route the wire harnesses properly can lead to radio ignition noise and cross-firing of the spark
plugs, or shorting of the leads to ground.
INSTALL OR CONNECT
1. Right wire harness to clips (16, 17 and 21). 2. Left wire harness to clips (17, 20, 21 and 23). 3.
Right wire harness to support (27). 4. Right wire harness support bolt / screw (28).
Tighten ^
Bolt / screw (28) to 40 Nm (30 lb ft.).
5. A/C compressor to bracket. 6. A/C compressor attaching bolts / screws and rear bracket nut.
Tighten A. A/C compressor bolts / screws to 50 Nm (37 lb ft.). B. A/C compressor rear bracket nut
to 41 Nm (30 lb ft.).
7. Serpentine drive belt tensioner and tensioner bolts / screws.
Tighten ^
Tensioner bolts / screws to 25 Nm (18 lb ft.).
8. Transmission oil cooler line support bolt / screw.
Tighten ^
Oil cooler line support bolt / screw to 1.9 Nm (17 lb in.).
9. Lower vehicle.
10. Serpentine drive belt.
With mechanical cooling fan: A. Radiator outlet pipe nuts from A/C compressor mounting studs.
Tighten ^
Radiator outlet pipe nuts to 16 Nm (12 lb ft.).
B. Mechanical fan pulley bracket nuts and bracket.
Tighten ^
Mechanical fan pulley bracket nuts to 50 Nm (37 lb .ft).
C. Mechanical fan pulley, fan and nuts.
^ Finger tighten only.
D. Fan belt.
Tighten ^
Mechanical fan nuts to 26 Nm (19 lb ft.).
E. Upper radiator fan shroud.
11. Air intake resonator. 12. Right bank spark plug wire boots to spark plugs. 13. Left bank spark
plug wire harness to clip (17) located behind AIR pump. 14. Left bank spark plug wire harness
support channel and bolts/screws (19). Rear bolt / screw (19) is located behind exhaust manifold
takedown.
Slide channel onto bolt / screw (19) then tighten using a 10 mm wrench.
15. Left bank spark plug wire harness boots to spark plugs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Distributor, Ignition > Distributor Cap > Component Information > Specifications
Distributor Cap: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Distributor, Ignition > Distributor Cap > Component Information > Service and Repair > Replacement
Distributor Cap: Service and Repair Replacement
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Distributor cap (30). 2. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten ^
Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
3. Vacuum harness assembly to distributor assembly. 4. Connect four-terminal PCM connector to
distributor. 5. Spark plug wire harness assemblies to distributor assembly. 6. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Distributor, Ignition > Distributor Cap > Component Information > Service and Repair > Replacement > Page 2403
Distributor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Distributor, Ignition > Ignition Rotor > Component Information > Specifications
Ignition Rotor: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Distributor Rotor Bolt / Screw ..............................................................................................................
....................................................... 0.7 Nm (6 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Distributor, Ignition > Ignition Rotor > Component Information > Specifications > Page 2407
Ignition Rotor: Service and Repair
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30). 7. Rotor bolts / screws (32) using J 39998 or
equivalent. 8. Rotor assembly (32). 9. Distributor cover (33) and shield (34).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Shield (34) and distributor cover (33). 2. Rotor (32). 3. Rotor bolts / screws (31) using J 39998 or
equivalent.
Tighten ^
Rotor bolts / screws (31) to 0.7 Nm (61 lb in.).
4. Distributor cap (30). 5. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Distributor, Ignition > Ignition Rotor > Component Information > Specifications > Page 2408
^ Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
6. Vacuum harness assembly to distributor assembly. 7. Connect four-terminal PCM connector to
distributor. 8. Spark plug wire harness assemblies to distributor assembly. 9. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications
Spark Plug: Specifications
Spark Plug Install Torque ....................................................................................................................
........................................................ 27 Nm (20 lb ft.)
Spark Plug Gap ...................................................................................................................................
........................................................ 1.27 mm (0.050")
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications > Page 2412
Spark Plug Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications > Page 2413
Spark Plug: Service Precautions
It is important that technicians wash their hands after handling coated spark plugs and before
smoking. The coating itself is a nonhazardous material and incidental contact will not cause any
adverse affects. However, exposure to polymer vapors (the result of a cigarette being coated from
handling, then burned) may cause flu like symptoms and should be avoided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications > Page 2414
Spark Plug ID
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications > Page 2415
Spark Plug: Description and Operation
Platinum-tipped, resistor-type, tapered-seat spark plugs are used on the engine assembly. No
gasket is used on these tapered-seat spark plugs. When replacing spark plugs, use only the type
specified.
Normal service is assumed to be a mixture of idling, slow speed, and high speed driving.
Occasional or intermittent high-speed driving is needed for good spark plug performance. It gives
increased combustion heat, burning away carbon or oxides that have built up from frequent idling,
or continual stop-and-go driving.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications > Page 2416
Spark Plug: Testing and Inspection
WORN OR DIRTY
Worn or dirty spark plugs may give satisfactory operation at idling speed, but frequently fail at
higher rpm. Faulty spark plugs may cause poor fuel economy, power loss, loss of speed, hard
starting and generally poor engine performance. Follow the scheduled maintenance service
recommendations to assure satisfactory spark plug performance.
NORMAL
Normal spark plug operation will result in brown to grayish - tan deposits appearing on the portion
of the spark plug that projects into the cylinder area. A small amount of red - brown, yellow, and
white powdery material may also be present on the insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels and lubricating oils with additives.
MISFIRING
Engine assemblies which are not running properly are often referred to as "misfiring." This means
the ignition spark is not igniting the fuel/air mixture at the proper time, While other ignition and fuel
system causes must also be considered, possible causes include ignition system conditions which
allow the spark voltage to reach ground in some other manner than by jumping across the air gap
at the tip of the spark plug, leaving the fuel/air mixture unburned. Misfiring may also occur when the
tip of the spark plug becomes overheated and ignites the mixture before the spark jumps. This is
referred to as "pre-ignition."
CARBON FOULING
Carbon fouling of the spark plug is indicated by dry, black carbon (soot) deposits on the portion of
the spark plug in the cylinder. Excessive idling and slow speeds under light engine loads can keep
the spark plug temperatures so low that these deposits are not burned off. Over - rich fuel mixtures
or poor ignition system output may also be the cause.
OIL FOULING
Oil fouling of the spark plug is indicated by wet oily deposits on the portion of the spark plug in the
cylinder. This may be caused by oil getting past worn piston rings. This condition also may occur
during break-in of new or newly overhauled engine assemblies.
DEPOSITS
Deposit fouling of the spark plug occurs when the normal red - brown, yellow or white deposits of
combustion by - products become sufficient to cause misfiring. In some cases, these deposits may
melt and form a shiny glaze on the insulator around the center electrode. If the fouling is found in
only one or two cylinders, valve stem clearances or intake valve seals may be allowing excess
lubricating oil to enter the cylinder, particularly if the deposits are heavier on the side of the spark
plug that was facing the intake valve.
CRACKED OR BROKEN
Cracked or broken insulators may be the result of improper installation or heat shock to the
insulator material. Upper insulators can be broken when a poorly fitting tool is used during
installation or removal, or when the park plug is hit from the outside. Cracks in the upper insulator
may be inside the shell and not visible. Also, the breakage may not cause problems until oil or
moisture penetrates the crack later.
A broken or cracked lower insulator tip (around the center electrode) may result from "heat shock"
(spark plug suddenly operating too hot).
"Heat shock" breakage in the lower insulator tip generally occurs during severe engine operating
conditions (high speeds or heavy loading) and may be caused by over - advanced timing or low
grade fuels. Heat shock refers to a rapid increase in the tip temperature that causes the insulator
material to crack.
Damage during gapping can happen if the gapping tool is pushed against the center electrode or
the insulator around it, causing the insulator to crack. When gapping a spark plug, make the
adjustment by only bending the ground side terminal, keeping the tool clear of other parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Spark Plug > Component Information > Specifications > Page 2417
Spark Plug: Service and Repair
Spark Plug Assembly
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Spark plug wire harness assemblies
from spark plugs. Refer to "Spark Plug Wire Harness Assembly Replacement" in this section.
^ Note positions of wires before removing.
NOTICE: Clean dirt and debris from spark plug recess areas.
3. Spark plugs from cylinder head assemblies.
NOTICE:
Be sure spark plugs thread smoothly into cylinder head assemblies and are fully seated. Cross threading or failing to fully seat spark plugs can cause overheating of spark plugs, exhaust blow-by,
or thread damage. Follow recommended torque specifications carefully. Over or under - tightening
can also cause severe damage to cylinder head assemblies or spark plug.
Check spark plug gap using a wire type gauge before installing. If spark plug gaps are not adjusted
correctly, engine idle quality may be seriously affected. A wire type gauge must be used (as
opposed to a flat feeler type gauge) to insure an accurate reading.
INSTALL OR CONNECT
1. Spark plugs to cylinder head assemblies.
Tighten ^
Spark plugs to 27 Nm (20 lb ft.).
2. Spark plug wire harness assemblies, routed properly as note during removal.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks >
Compression Check > System Information > Specifications
Compression Check: Specifications
The lowest reading cylinder should not be less than 70% of the highest and no cylinder reading
should be less than 689 kPa (100 psi). Perform compression test with engine at normal operating
temperature, spark plugs removed and throttle wide open.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Valve
Clearance > System Information > Specifications
Valve Clearance: Specifications
VALVE LASH
Turn rocker arm stud nut until all lash is eliminated (zero lash), then tighten nut additional turn in
1/4 turn increments.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Tune-up and Engine Performance Checks > Valve
Clearance > System Information > Specifications > Page 2424
Valve Clearance: Adjustments
Fig. 5 Valve Lash Adjustment
Adjust valves, Fig.5, with engine at normal operating temperature. Rotate engine until No. 1
cylinder is in position to fire. Adjust exhaust valves 1-3-4-8 and intake valves 1-2-5-7. Crank engine
one complete revolution, then adjust exhaust valves 2-5-6-7 and intake vales 3-4-6-8.
On all engines, the following procedure, performed with the engine running, should only be
performed if readjustment is required.
1. After engine has been warmed up to normal operating temperature, remove valve cover and
install a new valve cover gasket. 2. With engine running at idle speed, back off valve rocker arm
nut until rocker arm starts to clatter. 3. Turn rocker arm nut down slowly until clatter just stops. This
is the zero lash position. 4. Turn nut down 1/4 additional turn and pause 10 seconds until engine
runs smoothly. Repeat additional 1/4 turns, pausing 10 seconds each time,
until nut has been turned down the number of turns listed in "Valve Clearance Specifications chart
from the zero lash position. This preload adjustment must be done slowly to allow lifter to adjust
itself to prevent the possibility of interference between valve head and top of piston, which might
result in internal damage and/or bent push rods. Noisy lifters should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Water Pump > Component Information > Service
and Repair > Coolant Pump Driveshaft Assembly
Water Pump: Service and Repair Coolant Pump Driveshaft Assembly
This Article has been updated with TSB No. 57-61-28
COOLANT PUMP DRIVESHAFT ASSEMBLY
Fig. 23 Water Pump & Thermostat Replacement
TOOLS REQUIRED:
^ J 39243 Driven Gear Assembly Remover
^ J 41546 Driven Gear Assembly Installer
^ J 39089 Coolant Pump Shaft 0-Ring Protector
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Water Pump > Component Information > Service
and Repair > Coolant Pump Driveshaft Assembly > Page 2429
REMOVE OR DISCONNECT
1. Engine front cover assembly. 2. Rotate crankshaft assembly until timing marks punched on
crankshaft sprocket and camshaft sprocket are aligned. 3. Camshaft sprocket bolts/screws. 4.
Camshaft sprocket and timing chain assembly.
NOTICE: Do not turn the crankshaft assembly after the timing chain has been removed to prevent
damage to piston assemblies or valves.
5. Coolant pump bearing retainer bolts/screws and coolant pump driveshaft assembly using J
39243.
^ Remove and discard 0-ring from coolant pump drive-shaft assembly.
INSTALL OR CONNECT
1. Coolant pump drive shaft assembly using J 39092. 2. Coolant pump bearing retainer
bolts/screws.
TIGHTEN
^ Coolant pump bearing retainer bolts/screws to 12 Nm (108 lb. in.).
3. Camshaft sprocket and timing chain assembly.
^ Camshaft sprocket and coolant pump driveshaft gears must mesh, or damage to camshaft
retainer could occur.
4. Camshaft sprocket bolts/screws.
^ Make sure that camshaft and crankshaft timing marks align.
TIGHTEN
^ Camshaft sprocket bolts/screws to 28 Nm (21 lb. ft.).
5. New 0-ring to coolant pump driveshaft assembly using J 39089. 6. Engine front cover assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Water Pump > Component Information > Service
and Repair > Coolant Pump Driveshaft Assembly > Page 2430
Water Pump: Service and Repair Water/Coolant Pump
WATER PUMP REPLACEMENT
Fig. 17 Water Pump Replacement
REMOVAL PROCEDURE
The camshaft sprocket gear drives the water pump by using a drive shaft and coupling. Keep the
ignition wires connected to the distributor until the water pump is removed and all the coolant has
been drained.
1. Drain the engine coolant. 2. Remove the air cleaner resonator bracket nuts, if equipped with a
mechanical fan. 3. If the vehicle is equipped with a mechanical fan, remove the air cleaner
resonator by loosening the clamp and sliding the resonator off the studs. 4. If the vehicle is
equipped with a mechanical fan, remove the air intake duct. 5. If the vehicle is equipped with a
mechanical fan, remove the radiator fan upper shroud. 6. If the vehicle is equipped with a
mechanical fan, remove the fan belt from the tensioner. 7. If the vehicle is equipped with a
mechanical fan, remove the fan blade clutch nuts and the fan blade with the clutch attached. 8.
Remove the engine coolant and the heater hoses from the water pump. 9. If the vehicle is
equipped with a mechanical fan, remove the fan pulley.
10. If the vehicle is equipped with a mechanical fan, remove the coolant fan pulley bracket nuts. 11.
If the vehicle is equipped with a mechanical fan, remove the coolant fan pulley bracket. 12.
Remove the electrical connector from the coolant sensor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Water Pump > Component Information > Service
and Repair > Coolant Pump Driveshaft Assembly > Page 2431
13. Remove the secondary air injection pump and bracket. 14. Remove the water pump bolts and
the stud. 15. Remove the water pump and gaskets. 16. Remove the water pump driveshaft
coupling and the seals.
^ Discard the seals.
CLEAN
^ The water pump gasket surfaces.
^ The water pump bolts.
^ The coolant fan pulley bracket studs, if removed.
INSTALLATION PROCEDURE
1. Install the water pump driveshaft coupling and the new seals. 2. Install the water pump and the
gaskets. 3. Install the water pump bolts and the stud.
TIGHTEN
^ Bolts and the stud to 41 Nm (30 lb ft).
NOTICE: Use the correct fastener in the correct location. Replacement fasteners must be the
correct part number for that application. Fasteners requiring replacement or fasteners requiring the
use of thread locking compound or sealant are identified in the service procedure. Do not use
paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified.
These coatings affect fastener torque and joint clamping force and may damage the fastener. Use
the correct tightening sequence and specifications when installing fasteners in order to avoid
damage to parts and systems.
4. Install the secondary air injection pump and bracket. Refer to Refer to Air Pump in Engine
Controls. 5. Install the electrical connector to the coolant sensor. 6. Install the coolant fan pulley
bracket, if removed. 7. Install the coolant fan pulley bracket nuts, if removed.
TIGHTEN
^ Nuts to 50 Nm (37 lb ft).
8. Install the fan pulley, if removed. 9. Install the fan blade with the clutch attached and the nuts, if
removed.
TIGHTEN
^ Nuts to 26 Nm (19 lb ft).
10. Install the engine coolant hoses and the heater hoses to the water pump. 11. Install the fan belt
to the tensioner if the fan belt has been removed. 12. Install the radiator fan upper shroud if the
radiator fan upper shroud has been removed. 13. Install the air intake duct, if removed. 14. If the air
cleaner resonator has been removed, install the air cleaner resonator by sliding the resonator over
the studs and tightening the clamp until
snug.
15. Install the air cleaner resonator bracket nuts, if removed.
TIGHTEN
^ Nuts to 10 Nm (89 lb in).
16. Refill and bleed the cooling system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Engine > Water Pump > Component Information > Service
and Repair > Coolant Pump Driveshaft Assembly > Page 2432
Water Pump: Service and Repair Water Pump Disassembly
The OEM service manual does not provide water pump assembly service and repair information.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant > Component Information >
Technical Service Bulletins > Cooling System - Coolant Recycling Information
Coolant: Technical Service Bulletins Cooling System - Coolant Recycling Information
Bulletin No.: 00-06-02-006D
Date: August 15, 2006
INFORMATION
Subject: Engine Coolant Recycling and Warranty Information
Models: 2007 and Prior GM Passenger Cars and Trucks (Including Saturn) 2007 and Prior
HUMMER Vehicles 2005-2007 Saab 9-7X
Attention:
Please address this bulletin to the Warranty Claims Administrator and the Service Manager.
Supercede:
This bulletin is being revised to adjust the title and Include Warranty Information. Please discard
Corporate Bulletin Number 00-06-02-006C (Section 06 - Engine/Propulsion System).
Coolant Reimbursement Policy
General Motors supports the use of recycled engine coolant for warranty repairs/service, providing
a GM approved engine coolant recycling system is used. Recycled coolant will be reimbursed at
the GMSPO dealer price for new coolant plus the appropriate mark-up. When coolant replacement
is required during a warranty repair, it is crucial that only the relative amount of engine coolant
concentrate be charged, not the total diluted volume. In other words: if you are using two gallons of
pre-diluted (50:50) recycled engine coolant to service a vehicle, you may request reimbursement
for one gallon of GM Goodwrench engine coolant concentrate at the dealer price plus the
appropriate warranty parts handling allowance.
Licensed Approved DEX-COOL(R) Providers
Important:
USE OF NON-APPROVED VIRGIN OR RECYCLED DEX-COOL(R) OR DEVIATIONS IN THE
FORM OF ALTERNATE CHEMICALS OR ALTERATION OF EQUIPMENT, WILL VOID THE GM
ENDORSEMENT, MAY DEGRADE COOLANT SYSTEM INTEGRITY AND PLACE THE
COOLING SYSTEM WARRANTY UNDER JEOPARDY.
Shown in Table 1 are the only current licensed and approved providers of DEX-COOL(R). Products
that are advertised as "COMPATIBLE" or "RECOMMENDED" for use with DEX-COOL(R) have not
been tested or approved by General Motors. Non-approved coolants may degrade the
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Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant > Component Information >
Technical Service Bulletins > Cooling System - Coolant Recycling Information > Page 2438
coolant system integrity and will no longer be considered a 5 yr/150,000 mile (240,000 km) coolant.
Coolant Removal Services/Recycling
The tables include all coolant recycling processes currently approved by GM. Also included is a
primary phone number and demographic information. Used DEX-COOL(R) can be combined with
used conventional coolant (green) for recycling. Depending on the recycling service and/or
equipment, it is then designated as a conventional 2 yr/30,000 mile (50,000 km) coolant or
DEX-COOL(R) 5 yr/150,000 mile (240,000 km) coolant. Recycled coolants as designated in this
bulletin may be used during the vehicle(s) warranty period.
DEX-COOL(R) Recycling
The DEX-COOL(R) recycling service listed in Table 2 has been approved for recycling waste
engine coolants (DEX-COOL) or conventional) to DEX-COOL(R) with 5 yr/150,000 mile (240,000
km) usability. Recycling Fluid Technologies is the only licensed provider of Recycled
DEX-COOL(R) meeting GM6277M specifications and utilizes GM approved inhibitor packages.
This is currently a limited program being monitored by GM Service Operations which will be
expanded as demand increases.
Conventional (Green) Recycling
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Technical Service Bulletins > Cooling System - Coolant Recycling Information > Page 2439
Processes shown in the Table 3 are capable of recycling waste engine coolants (DEX-COOL(R) or
conventional) to a conventional (green) coolant. Recycling conventional coolant can be
accomplished at your facility by a technician using approved EQUIPMENT (listed by model number
in Table 3), or by an approved coolant recycling SERVICE which may recycle the coolant at your
facility or at an offsite operation. Refer to the table for GM approved coolant recyclers in either of
these two categories. Should you decide to recycle the coolant yourself, strict adherence to the
operating procedures is imperative. Use ONLY the inhibitor chemicals supplied by the respective
(GM approved) recycling equipment manufacturer.
Sealing Tablets
Cooling System Sealing Tablets (Seal Tabs) should not be used as a regular maintenance item
after servicing an engine cooling system. Discoloration of coolant can occur if too many seal tabs
have been inserted into the cooling system. This can occur if seal tabs are repeatedly used over
the service life of a vehicle. Where appropriate, seal tabs may be used if diagnostics fail to repair a
small leak in the cooling system. When a condition appears in which seal tabs may be
recommended, a specific bulletin will be released describing their proper usage.
Water Quality
The integrity of the coolant is dependent upon the quality of DEX-COOL(R) and water.
DEX-COOL(R) is a product that has enhanced protection capability as well as an extended service
interval. These enhanced properties may be jeopardized by combining DEX-COOL(R) with poor
quality water. If you suspect the water in your area of being poor quality, it is recommended you
use distilled or de-ionized water with DEX-COOL(R).
"Pink" DEX-COOL(R)
DEX-COOL(R) is orange in color to distinguish it from other coolants. Due to inconsistencies in the
mixing of the dyes used with DEX-COOL(R), some batches may appear pink after time. The color
shift from orange to pink does not affect the integrity of the coolant, and still maintains the 5
yr/150,000 mile (240,000 km) service interval.
Back Service
Only use DEX-COOL(R) if the vehicle was originally equipped with DEX-COOL(R).
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Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant > Component Information >
Technical Service Bulletins > Cooling System - Coolant Recycling Information > Page 2440
Contamination
Mixing conventional green coolant with DEX-COOL(R) will degrade the service interval from 5
yrs./150,000 miles (240,000 km) to 2 yrs./30,000 miles (50,000 km) if left in the contaminated
condition. If contamination occurs, the cooling system must be flushed twice immediately and
re-filled with a 50/50 mixture of DEX-COOL(R) and clean water in order to preserve the enhanced
properties and extended service interval of DEX-COOL(R).
After 5 years/150,000 miles (240,000 km)
After 5 yrs/150,000 miles (240,000 km), the coolant should be changed, preferably using a coolant
exchanger. If the vehicle was originally equipped with DEX-COOL(R) and has not had problems
with contamination from non-DEX-COOL(R) coolants, then the service interval remains the same,
and the coolant does not need to be changed for another 5 yrs/150,000 miles (240,000 km)
Equipment (Coolant Exchangers)
The preferred method of performing coolant replacement is to use a coolant exchanger. A coolant
exchanger can replace virtually all of the old coolant with new coolant. Coolant exchangers can be
used to perform coolant replacement without spillage, and facilitate easy waste collection. They
can also be used to lower the coolant level in a vehicle to allow for less messy servicing of cooling
system components. It is recommended that you use a coolant exchanger with a vacuum feature
facilitates removing trapped air from the cooling system. This is a substantial time savings over
repeatedly thermo cycling the vehicle and topping-off the radiator. The vacuum feature also allows
venting of a hot system to relieve system pressure. Approved coolant exchangers are available
through the GMDE (General Motors Dealer Equipment) program.
For refilling a cooling system that has been partially or fully drained for repairs other than coolant
replacement, the Vac-N-Fill Coolant Refill Tool (GE-47716) is recommended to facilitate removal of
trapped air from the cooling system during refill.
Disclaimer
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Technical Service Bulletins > Cooling System - Coolant Recycling Information > Page 2441
Coolant: Technical Service Bulletins Engine Coolant - Information on Back Service
File In Section: 6 - Engine
Bulletin No: 53-62-02
Date: November, 1995
Subject: DEX-COOL(TM) Engine Coolant - Information on Back service
Models: 1994-95 Passenger Cars and Trucks
A new extended-life engine coolant called DEX-COOL(TM) is currently being used in all General
Motors' vehicles (excluding Chevrolet Geo and Saturn). Refer to bulletin 53-62-01 for general
service information.
Backservice
DEX-COOL(TM) may be used in General Motors vehicles originally built with conventional (green)
coolant with the following considerations:
^ Vehicles eligible for back service are 1994 and 1995 models (excluding 1994 J Body with 4
cylinder engines).
^ The service interval for DEX-COOL(TM) introduced into an older model vehicle originally built
with "green" coolant will be 2 years/30,000 miles (50,000 Km) (not 5 years/100,000 miles (160,000
Km)).
^ All the "green" coolant must be removed from the cooling system by means of a system flush.
This may be accomplished with a water flushing device or a GMDE waterless coolant changer (use
a unit dedicated to "green" coolant, not DEX-COOL TM).
Important:
When using a GMDE waterless coolant changer, conduct the procedure twice, once with water,
and once with DEX-COOL(TM)
Backservice with DEX-COOL(TM) is advocated because of enhanced water pump seal durability
experienced with this coolant.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Technical Service Bulletins > Cooling System - Coolant Recycling Information > Page 2442
Coolant: Technical Service Bulletins Extended Life Engine Coolant - DEX-COOL(TM)
FILE IN SECTION: 6 - Engine
BULLETIN NO.: 53-62-01
DATE: June, 1995
SUBJECT: New Extended Life Engine Coolant Known as DEX-COOL(TM)
MODELS: 1995 Passenger Cars and Trucks
A new extended life engine coolant known as "DEX-COOL(TM)" will be used in all General Motors
vehicles. Some trucks will be filled with DEX-COOL TM beginning in late May; most vehicles will
convert in July, 1995 with the remaining vehicles to convert by January, 1996. Most of these
vehicles will be 1995 models. All production for 1996 models will utilize DEX-COOL(TM). It is
imperative to note the following about DEX-COOL(TM) engine coolant:
^ IT IS ORANGE IN COLOR TO DISTINGUISH IT FROM CONVENTIONAL COOLANT.
^ THE SERVICE CHANGE INTERVAL ON VEHICLES WHICH ARE BUILT WITH DEX-COOL(TM)
IS 5 YEARS/100,000 MILES, WHICHEVER OCCURS FIRST.
^ TO MAINTAIN FULL CORROSION PROTECTION DURABILITY, DEX-COOL (TM) MUST NOT
BE MIXED WITH CONVENTIONAL (CONTAINING SILICATE) ENGINE COOLANTS.
^ DEX-COOL(TM) IS AN ETHYLENE GYLCOL BASED PRODUCT, THEREFORE, BOIL AND
FREEZE PROTECTION ARE MEASURED IN THE SAME FASHION AS CONVENTIONAL
COOLANTS.
TO FULLY REALIZE ITS MANY ADVANTAGES, DEX-COOL(TM) MUST NEVER BE MIXED
WITH CONVENTIONAL COOLANTS.
It is particularly important to top-off new vehicles with DEX-COOL(TM) DEX-COOL(TM) forms a
protective film on aluminum surfaces, however, if a vehicle with less than 3,000 miles is topped-off
with conventional coolant, aluminum corrosion may occur. DEX-COOL(TM) CAN BECOME
CONTAMINATED BY INADVERTENTLY TOPPING-OFF WITH CONVENTIONAL COOLANT,
ADDING CONVENTIONAL COOLANT TO THE RADIATOR, OR EVEN IF FILL/DRAIN
CONTAINERS ARE SHARED BETWEEN COOLANTS.
If contamination occurs on a new vehicle (i.e. during vehicle prep), the cooling system must be
immediately drained and refilled with DEX-COOL(TM) If contamination with conventional coolant
occurs after the vehicle has been driven for at least 3,000 miles, no short-term problems will occur;
however, the service change interval will be reduced from 5 years/100,000 miles to 2 years/30,000
miles. More information on DEX-COOL(TM) engine coolant service procedures can be found in the
1996 Service Manuals and a video tape which will be issued by STG.
Vehicles which contain DEX-COOL(TM) can be identified by a special underhood label which
states "USE DEX-COOL(TM) COOLANT ONLY. .. meeting Spec. 6277M". They may also be
identified by the coolant's orange color and the information contained in the Owner's Manual.
REGARDING COOLANT RECYCLING
Engine coolant recycling is affected by DEX-COOL(TM) as follows. Used DEX-COOL(TM) can be
mixed into your "used" conventional coolant storage vessel and the mixture recycled in the same
manner as you are accustomed to. This recycled mixture of conventional and DEX-COOL(TM)
coolant must be used as a 2 year/30,000 mile conventional coolant and should not be used in
vehicles originally equipped with DEX-COOL(TM) When servicing vehicles originally equipped with
DEX-COOL(TM), use only Goodwrench-DEX-COOL(TM) Additional research will be conducted to
evaluate the feasibility of recycling DEX-COOL(TM) to DEX-COOL(TM) in the near future.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant > Component Information >
Technical Service Bulletins > Page 2443
Coolant: Specifications
Mixture
..........................................................................................................................................................
50/50 of water and ethylene glycol antifreeze
Capacity
Without Heavy-Duty Radiator
..............................................................................................................................................................
13.5 liters (14.3 qt) With Heavy-Duty Radiator ....................................................................................
............................................................................... 13.8 liters (14.6 qt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant Level Indicator Lamp >
Component Information > Description and Operation
Coolant Level Indicator Lamp: Description and Operation
DESCRIPTION
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
OPERATION
Some vehicles use a buzzer or indicator lamp to convey a low coolant level condition. The buzzer
or lamp is activated by a sensor, located in the radiator, when the coolant level becomes one quart
low, or more.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant Level Indicator Lamp >
Component Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant Level Low
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator Off W/Coolant Level
Low
Fig. 97 Chart 6: Low Coolant Level Indicator Inoperative W/Coolant Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant Level Indicator Lamp >
Component Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant Level Low > Page 2449
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator On w/Coolant Level
OK
Fig. 96 Chart 5: Low Coolant Level Indicator On W/Coolant Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant Level Indicator Lamp >
Component Information > Testing and Inspection > Page 2450
Coolant Level Indicator Lamp: Service and Repair
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant Level Sensor > Component
Information > Locations
Rear Side Radiator Support, Coolant Fans
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Coolant Reservoir > Component
Information > Locations
Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator Cooling Fan > Radiator Cooling
Fan Motor > Component Information > Locations > Secondary Engine Electric Cooling Fan Connector
Rear Side Radiator Support, Coolant Fans
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator Cooling Fan > Radiator Cooling
Fan Motor > Component Information > Locations > Secondary Engine Electric Cooling Fan Connector > Page 2462
Rear Side Radiator Support, Coolant Fans
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator Cooling Fan > Radiator Cooling
Fan Motor > Component Information > Diagrams > Diagram Information and Instructions
Radiator Cooling Fan Motor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2465
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2466
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2467
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator Cooling Fan > Radiator Cooling
Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2468
Fig.2-Symbols (Part 2 Of 3)
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Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator Cooling Fan > Radiator Cooling
Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2469
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Radiator Cooling Fan Motor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2484
Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2485
Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2486
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2488
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2489
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2490
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2491
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2492
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2493
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2494
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2495
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2496
Radiator Cooling Fan Motor: Electrical Diagrams
Base And V03 Extra Capacity Cooling Only
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2497
V08 Heavy Duty Cooling Only
Wiring Diagrams
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Fan Motor > Component Information > Diagrams > Diagram Information and Instructions > Page 2498
Cooling Fans, A/C And I/P Indicators
This diagram is one part of the Complete set of Powertrain Wiring Diagrams located under
Powertrain Management. Refer to this area if you need the accompanying diagram. See:
Powertrain Management/Diagrams/Electrical Diagrams
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Fan Motor > Component Information > Description and Operation > Cooling Fan (Heavy Duty)
Radiator Cooling Fan Motor: Description and Operation Cooling Fan (Heavy Duty)
The primary engine cooling fan in this system is mechanical. The secondary cooling fan is an
electric fan.
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Fan Motor > Component Information > Description and Operation > Cooling Fan (Heavy Duty) > Page 2501
Radiator Cooling Fan Motor: Description and Operation Cooling Fans
This two fan system is PCM controlled by inputs received from the engine coolant temperature
sensor, vehicle speed sensor, and the A/C system. The PCM commands the primary cooling fan
On when engine coolant temperature exceeds 225° F, A/C head pressure is above 225 psi and
when certain diagnostic trouble codes are set. The primary fan is commanded Off when engine
coolant temperature drops below 217° F, or A/C head pressure drops below 180 psi.
The secondary cooling fan is commanded On when the engine coolant temperature exceeds 232°
F, A/C head pressure is above 248 psi or certain diagnostic trouble codes are set. The PCM
commands the secondary fan Off when engine coolant temperature drops below 224° F, or A/C
head pressure drops below 203 psi.
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Fan Motor Relay > Component Information > Locations
Radiator Cooling Fan Motor Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
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Fan Motor Relay > Component Information > Locations > Page 2505
Engine Cooling Fan Relay Primary, Secondary
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Fan Temperature Sensor / Switch > Component Information > Locations
Radiator Cooling Fan Temperature Sensor / Switch: Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
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Component Information > Description and Operation
Fan Clutch: Description and Operation
Fig. 1 Typical Variable Speed Cooling Fan
Fig. 2 Variable Speed Fan W/Flat Bi-Metal Thermostatic Spring
Fig. 3 Variable-Speed Fan W/Coiled Bi-Metal Thermostatic Spring
The fan drive clutch, Fig. 1 , is a fluid coupling containing silicone oil. Fan speed is regulated by the
torque carrying capacity of the silicone oil. The more silicone oil in the coupling, the greater the fan
speed; the less silicone oil, the slower the fan speed.
Two types of fan drive clutches are in use. On one, Fig.2 , a bi-metallic strip and control piston on
the front of the fluid coupling regulates the amount of silicone oil entering the coupling. The
bi-metallic strip flexes outward with an increase in surrounding temperature and allows a piston to
move outward. The piston opens a valve regulating the flow of silicone oil into the coupling from a
reserve chamber. The silicone oil is returned to the reserve chamber through a bleed hole when
the valve is closed.
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Component Information > Description and Operation > Page 2512
On the other type of fan drive clutch, Fig. 3 , a heat-sensitive, bi-metal spring connected to an
opening plate brings about a similar result. Both units cause the fan speed to increase with a rise in
temperature and to decrease as the temperature goes down.
In some cases a Flex-Fan is used instead of a Fan Drive Clutch. Flexible blades vary the volume of
air being drawn through the radiator, automatically increasing the pitch at low engine speeds.
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Component Information > Description and Operation > Page 2513
Fan Clutch: Testing and Inspection
Fig. 4 Bi-Metal Spring Disengagement
Do not operate the engine until the fan has been checked for possible cracks and separations.
Run the engine at a fast idle speed (1000 RPM) until normal operating temperature is reached.
This process can be expedited by blocking off the front of the radiator with a suitable piece of
cardboard. Regardless of temperature, the unit must be operated for at least five minutes before
being tested.
Stop the engine and, using a glove or a cloth, immediately check the effort required to turn the fan.
If considerable effort is required, it can be assumed that the coupling is operating satisfactorily. If
very little effort is required to turn the fan, it is an indication that the coupling is not operating
properly and should be replaced.
If the clutch fan is the coiled bi-metal spring type, it may be tested while the vehicle is being driven.
To check, disconnect the bi-metal spring, Fig. 4 , and rotate the spring 90° counterclockwise. This
disables the temperature controlled free wheeling feature and the clutch performs like a
conventional fan. If this cures the overheating condition, replace the fan clutch.
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Component Information > Description and Operation > Page 2514
Fan Clutch: Service and Repair
Fig. 1 Typical Variable Speed Cooling Fan
To prevent silicone fluid from draining into fan drive bearing, do not store or place drive unit on
bench with rear of shaft pointing downward.
The removal procedure for either type of fan clutch assembly is similar for all vehicles. The unit
must be unfastened from the water pump, then it may be lifted from the vehicle.
The type of unit shown in Fig. 2 may be partially disassembled for inspection and cleaning as
follows:
1. Remove capscrews holding assembly together and separate fan from drive clutch. 2. Remove
metal strip on front of fan clutch by pushing one end toward fan clutch body to clear retaining
bracket. 3. Push strip aside until its opposite end springs out of place, then remove small control
piston. 4. Inspect piston for free movement in coupling device. If piston sticks, clean it with emery
cloth. If bi-metal strip is damaged, replace entire unit.
These strips are not interchangeable.
5. When reassembling, install control piston so that projection on end will contact metal strip, then
install metal strip. 6. After reassembly, clean clutch drive with a solvent soaked cloth. Avoid dipping
clutch assembly in any type of liquid. 7. Install assembly in vehicle.
The coil spring type of fan clutch cannot be disassembled, serviced or repaired. If it does not
function properly, it must be replaced with a new unit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Engine - Coolant Temperature
Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information > Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Engine - Coolant Temperature
Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information > Specifications > Page
2519
Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Engine - Coolant Temperature
Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information > Specifications > Page
2520
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Engine - Coolant Temperature
Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component Information > Specifications > Page
2521
Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Engine - Coolant Temperature
Sensor/Switch > Radiator Cooling Fan Temperature Sensor / Switch > Component Information > Locations
Radiator Cooling Fan Temperature Sensor / Switch: Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Engine - Coolant Temperature
Sensor/Switch > Temperature Sensor (Gauge) > Component Information > Locations
Temperature Sensor (Gauge): Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Heater Core > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators
Heater Core: Technical Service Bulletins Cooling System, A/C - Aluminum Heater Cores/Radiators
INFORMATION
Bulletin No.: 05-06-02-001A
Date: July 16, 2008
Subject: Information On Aluminum Heater Core and/or Radiator Replacement
Models: 2005 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2003-2005
HUMMER H2
Supercede:
This bulletin is being revised to update the Warranty Information. Please discard Corporate Bulletin
Number 05-06-02-001 (Section 06 - Engine/Propulsion System).
Important:
2004-05 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX-COOL(R). Refer to the
flushing procedure explained later in this bulletin.
The following information should be utilized when servicing aluminum heater core and/or radiators
on repeat visits. A replacement may be necessary because erosion, corrosion, or insufficient
inhibitor levels may cause damage to the heater core, radiator or water pump. A coolant check
should be performed whenever a heater core, radiator, or water pump is replaced. The following
procedures/ inspections should be done to verify proper coolant effectiveness.
Caution:
To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot.
The cooling system will release scalding fluid and steam under pressure if the radiator cap or surge
tank cap is removed while the engine and radiator are still hot.
Important:
If the vehicle's coolant is low, drained out, or the customer has repeatedly added coolant or water
to the system, then the system should be completely flushed using the procedure explained later in
this bulletin.
Technician Diagnosis
^ Verify coolant concentration. A 50% coolant/water solution ensures proper freeze and corrosion
protection. Inhibitor levels cannot be easily measured in the field, but can be indirectly done by the
measurement of coolant concentration. This must be done by using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale), or equivalent, coolant tester. The Refractometer
uses a minimal amount of coolant that can be taken from the coolant recovery reservoir, radiator or
the engine block. Inexpensive gravity float testers (floating balls) will not completely analyze the
coolant concentration fully and should not be used. The concentration levels should be between
50% and 65% coolant concentrate. This mixture will have a freeze point protection of -34 degrees
Fahrenheit (-37 degrees Celsius). If the concentration is below 50%, the cooling system must be
flushed.
^ Inspect the coolant flow restrictor if the vehicle is equipped with one. Refer to Service Information
(SI) and/or the appropriate Service Manual for component location and condition for operation.
^ Verify that no electrolysis is present in the cooling system. This electrolysis test can be performed
before or after the system has been repaired. Use a digital voltmeter set to 12 volts. Attach one test
lead to the negative battery post and insert the other test lead into the radiator coolant, making sure
the lead does not touch the filler neck or core. Any voltage reading over 0.3 volts indicates that
stray current is finding its way into the coolant. Electrolysis is often an intermittent condition that
occurs when a device or accessory that is mounted to the radiator is energized. This type of current
could be caused from a poorly grounded cooling fan or some other accessory and can be verified
by watching the volt meter and turning on and off various accessories or engage the starter motor.
Before using one of the following flush procedures, the coolant recovery reservoir must be
removed, drained, cleaned and reinstalled before refilling the system.
Notice:
^ Using coolant other than DEX‐COOL(R) may cause premature engine, heater core or
radiator corrosion. In addition, the engine coolant may require changing sooner, at 30,000 miles
(50,000 km) or 24 months, whichever occurs first. Any repairs would not be covered by your
warranty. Always use DEX‐COOL(R) (silicate free) coolant in your vehicle.
^ If you use an improper coolant mixture, your engine could overheat and be badly damaged. The
repair cost would not be covered by your warranty. Too much water in the mixture can freeze and
crack the engine, radiator, heater core and other parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Heater Core > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 2532
Flushing Procedures using DEX-COOL(R)
Important:
The following procedure recommends refilling the system with DEX-COOL(R), P/N 12346290 (in
Canada, use P/N 10953464), GM specification 6277M. This coolant is orange in color and has a
service interval of 5 years or 240,000 km (150,000 mi). However, when used on vehicles built prior
to the introduction of DEX-COOL(R), maintenance intervals will remain the same as specified in the
Owner's Manual.
^ If available, use the approved cooling system flush and fill machine (available through the GM
Dealer Equipment Program) following the manufacturer's operating instructions.
^ If approved cooling system flush and fill machine is not available, drain the coolant and dispose of
properly following the draining procedures in the appropriate Service Manual. Refill the system
using clear, drinkable water and run the vehicle until the thermostat opens. Repeat and run the
vehicle three (3) times to totally remove the old coolant or until the drained coolant is almost clear.
Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with
DEX‐COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M,
following the refill procedures in the appropriate Service Manual.
If a Service Manual is not available, fill half the capacity of the system with 100% DEX-COOL(R),
P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. Then slowly add clear,
drinkable water (preferably distilled) to the system until the level of the coolant mixture has reached
the base of the radiator neck. Wait two (2) minutes and reverify the coolant level. If necessary, add
clean water to restore the coolant to the appropriate level.
Once the system is refilled, reverify the coolant concentration using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. The concentration
levels should be between 50% and 65%.
Flushing Procedures using Conventional Silicated (Green Colored) Coolant
Important:
2004-2005 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX‐COOL(R).
The Aveo and Wave are filled with conventional, silicated engine coolant that is blue in color.
Silicated coolants are typically green in color and are required to be drained, flushed and refilled
every 30,000 miles (48,000 km). The Aveo and Wave are to be serviced with conventional, silicated
coolant. Use P/N 12378560 (1 gal) (in Canada, use P/N 88862159 (1 L). Refer to the Owner's
Manual or Service Information (SI) for further information on OEM coolant.
Important:
Do not mix the OEM orange colored DEX-COOL(R) coolant with green colored coolant when
adding coolant to the system or when servicing the vehicle's cooling system. Mixing the orange and
green colored coolants will produce a brown coolant which may be a customer dissatisfier and will
not extend the service interval to that of DEX-COOL(R). Conventional silicated coolants offered by
GM Service and Parts Operations are green in color.
^ If available, use the approved cooling system flush and fill machine (available through the GM
Dealer Equipment Program) following the manufacturer's operating instructions.
^ If approved cooling systems flush and fill machine is not available, drain coolant and dispose of
properly following the draining procedures in appropriate Service Manual. Refill the system using
clear, drinkable water and run vehicle until thermostat opens. Repeat and run vehicle three (3)
times to totally remove old coolant or until drained coolant is almost clear. Once the system is
completely flushed, refill the cooling system to a 50%-60% concentration with a good quality
ethylene glycol base engine coolant, P/N 12378560, 1 gal (in Canada, use P/N 88862159 1 L),
conforming to GM specification 1825M, or recycled coolant conforming to GM specification 1825M,
following the refill procedures in the appropriate Service Manual.
If a Service Manual is not available, fill half the capacity of the system with 100% good quality
ethylene glycol base (green colored) engine coolant, P/N 12378560 1 gal., (in Canada, use P/N
88862159 1 L) conforming to GM specification 1825M. Then slowly add clear, drinkable water
(preferably distilled) to system until the level of the coolant mixture has reached the base of the
radiator neck. Wait two (2) minutes and recheck coolant level. If necessary, add clean water to
restore coolant to the appropriate level.
Once the system is refilled, recheck the coolant concentration using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. Concentration levels
should be between 50% and 65%.
Parts Information
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Heater Core > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 2533
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Heater Core > Component Information >
Service and Repair > With Air Conditioning
Heater Core: Service and Repair With Air Conditioning
Fig. 21 Heater Core & Evaporator Core
1. Disconnect battery ground cable, then drain cooling system. 2. Remove heater outlet attaching
screw. 3. Disconnect heater core pipe fittings, then disengage pipe from fitting. 4. Remove
righthand instrument insulator panel attaching screws, then pull panel rearward to disconnect. 5.
Remove instrument panel lower reinforcement attaching nut and screw. 6. Disconnect lower
evaporator case vacuum electrical connectors. 7. Remove righthand pillar trim finish panel, then
roll carpet back to gain access. 8. Remove seven lower evaporator case attaching screws, then
remove lower evaporator case. 9. Remove heater core attaching straps and screws, then pull
heater core rearward working heater tubes out of seal, Fig. 21.
10. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Heater Core > Component Information >
Service and Repair > With Air Conditioning > Page 2536
Heater Core: Service and Repair Without Air Conditioning
1. Disconnect battery ground cable and drain cooling system. 2. Disconnect heater hoses from
heater core. Plug core outlets to prevent coolant spillage. 3. Disconnect electrical connections at
blower motor and resistor. 4. Detach heater wiring from clip at blower housing cover. 5. Remove
blower housing cover attaching screws, then remove blower housing cover. 6. Remove heater
core. 7. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Coolant Level Indicator Lamp > Component Information > Description and Operation
Coolant Level Indicator Lamp: Description and Operation
DESCRIPTION
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
OPERATION
Some vehicles use a buzzer or indicator lamp to convey a low coolant level condition. The buzzer
or lamp is activated by a sensor, located in the radiator, when the coolant level becomes one quart
low, or more.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Coolant Level Indicator Lamp > Component Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant
Level Low
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator Off W/Coolant Level
Low
Fig. 97 Chart 6: Low Coolant Level Indicator Inoperative W/Coolant Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Coolant Level Indicator Lamp > Component Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant
Level Low > Page 2543
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator On w/Coolant Level
OK
Fig. 96 Chart 5: Low Coolant Level Indicator On W/Coolant Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Coolant Level Indicator Lamp > Component Information > Testing and Inspection > Page 2544
Coolant Level Indicator Lamp: Service and Repair
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Temperature Gauge > Component Information > Description and Operation
Temperature Gauge: Description and Operation
DESCRIPTION
This temperature indicating system consists of a sending unit, located on the cylinder head,
electrical temperature gauge and an instrument voltage regulator.
OPERATION
As engine temperature increases or decreases, the resistance of the sending unit changes, in turn
controlling current flow through the gauge. When engine temperature is low sending unit resistance
is high, current flow through the gauge is restricted, and the gauge pointer remains against the stop
or moves very little. As engine temperature increases sending unit resistance decreases and
current flow through the gauge increases, resulting in increased pointer movement.
Troubleshooting for the electrical temperature indicating system is the same as for the electrical oil
pressure indicating system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Temperature Gauge > Component Information > Description and Operation > Page 2548
Temperature Gauge: Testing and Inspection
Fig. 104 Chart 2: Engine Coolant Temperature Gauge Inoperative Or Inaccurate
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Lamps and Indicators - Cooling System >
Temperature Warning Lamp/Indicator, Engine Cooling > Component Information > Description and Operation
Temperature Warning Lamp/Indicator: Description and Operation
DESCRIPTION
If the red light is not lit when the engine is being cranked, check for a burned out bulb, an open in
the light circuit, or a defective ignition switch.
If the red light is lit when the engine is running, check the wiring between light and switch for a
ground, temperature switch defective, or overheated cooling system. As a test circuit to check
whether the red bulb is functioning properly, a wire which is connected to the ground terminal of the
ignition switch is tapped into its circuit. When the ignition is in the start engine cranking position, the
ground terminal is grounded inside the switch and the red bulb will be lit. When the engine is
started and the ignition switch is in the on position, the test circuit is opened and the bulb is then
controlled by the temperature switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators
Radiator: Technical Service Bulletins Cooling System, A/C - Aluminum Heater Cores/Radiators
INFORMATION
Bulletin No.: 05-06-02-001A
Date: July 16, 2008
Subject: Information On Aluminum Heater Core and/or Radiator Replacement
Models: 2005 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2003-2005
HUMMER H2
Supercede:
This bulletin is being revised to update the Warranty Information. Please discard Corporate Bulletin
Number 05-06-02-001 (Section 06 - Engine/Propulsion System).
Important:
2004-05 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX-COOL(R). Refer to the
flushing procedure explained later in this bulletin.
The following information should be utilized when servicing aluminum heater core and/or radiators
on repeat visits. A replacement may be necessary because erosion, corrosion, or insufficient
inhibitor levels may cause damage to the heater core, radiator or water pump. A coolant check
should be performed whenever a heater core, radiator, or water pump is replaced. The following
procedures/ inspections should be done to verify proper coolant effectiveness.
Caution:
To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot.
The cooling system will release scalding fluid and steam under pressure if the radiator cap or surge
tank cap is removed while the engine and radiator are still hot.
Important:
If the vehicle's coolant is low, drained out, or the customer has repeatedly added coolant or water
to the system, then the system should be completely flushed using the procedure explained later in
this bulletin.
Technician Diagnosis
^ Verify coolant concentration. A 50% coolant/water solution ensures proper freeze and corrosion
protection. Inhibitor levels cannot be easily measured in the field, but can be indirectly done by the
measurement of coolant concentration. This must be done by using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale), or equivalent, coolant tester. The Refractometer
uses a minimal amount of coolant that can be taken from the coolant recovery reservoir, radiator or
the engine block. Inexpensive gravity float testers (floating balls) will not completely analyze the
coolant concentration fully and should not be used. The concentration levels should be between
50% and 65% coolant concentrate. This mixture will have a freeze point protection of -34 degrees
Fahrenheit (-37 degrees Celsius). If the concentration is below 50%, the cooling system must be
flushed.
^ Inspect the coolant flow restrictor if the vehicle is equipped with one. Refer to Service Information
(SI) and/or the appropriate Service Manual for component location and condition for operation.
^ Verify that no electrolysis is present in the cooling system. This electrolysis test can be performed
before or after the system has been repaired. Use a digital voltmeter set to 12 volts. Attach one test
lead to the negative battery post and insert the other test lead into the radiator coolant, making sure
the lead does not touch the filler neck or core. Any voltage reading over 0.3 volts indicates that
stray current is finding its way into the coolant. Electrolysis is often an intermittent condition that
occurs when a device or accessory that is mounted to the radiator is energized. This type of current
could be caused from a poorly grounded cooling fan or some other accessory and can be verified
by watching the volt meter and turning on and off various accessories or engage the starter motor.
Before using one of the following flush procedures, the coolant recovery reservoir must be
removed, drained, cleaned and reinstalled before refilling the system.
Notice:
^ Using coolant other than DEX‐COOL(R) may cause premature engine, heater core or
radiator corrosion. In addition, the engine coolant may require changing sooner, at 30,000 miles
(50,000 km) or 24 months, whichever occurs first. Any repairs would not be covered by your
warranty. Always use DEX‐COOL(R) (silicate free) coolant in your vehicle.
^ If you use an improper coolant mixture, your engine could overheat and be badly damaged. The
repair cost would not be covered by your warranty. Too much water in the mixture can freeze and
crack the engine, radiator, heater core and other parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 2556
Flushing Procedures using DEX-COOL(R)
Important:
The following procedure recommends refilling the system with DEX-COOL(R), P/N 12346290 (in
Canada, use P/N 10953464), GM specification 6277M. This coolant is orange in color and has a
service interval of 5 years or 240,000 km (150,000 mi). However, when used on vehicles built prior
to the introduction of DEX-COOL(R), maintenance intervals will remain the same as specified in the
Owner's Manual.
^ If available, use the approved cooling system flush and fill machine (available through the GM
Dealer Equipment Program) following the manufacturer's operating instructions.
^ If approved cooling system flush and fill machine is not available, drain the coolant and dispose of
properly following the draining procedures in the appropriate Service Manual. Refill the system
using clear, drinkable water and run the vehicle until the thermostat opens. Repeat and run the
vehicle three (3) times to totally remove the old coolant or until the drained coolant is almost clear.
Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with
DEX‐COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M,
following the refill procedures in the appropriate Service Manual.
If a Service Manual is not available, fill half the capacity of the system with 100% DEX-COOL(R),
P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. Then slowly add clear,
drinkable water (preferably distilled) to the system until the level of the coolant mixture has reached
the base of the radiator neck. Wait two (2) minutes and reverify the coolant level. If necessary, add
clean water to restore the coolant to the appropriate level.
Once the system is refilled, reverify the coolant concentration using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. The concentration
levels should be between 50% and 65%.
Flushing Procedures using Conventional Silicated (Green Colored) Coolant
Important:
2004-2005 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX‐COOL(R).
The Aveo and Wave are filled with conventional, silicated engine coolant that is blue in color.
Silicated coolants are typically green in color and are required to be drained, flushed and refilled
every 30,000 miles (48,000 km). The Aveo and Wave are to be serviced with conventional, silicated
coolant. Use P/N 12378560 (1 gal) (in Canada, use P/N 88862159 (1 L). Refer to the Owner's
Manual or Service Information (SI) for further information on OEM coolant.
Important:
Do not mix the OEM orange colored DEX-COOL(R) coolant with green colored coolant when
adding coolant to the system or when servicing the vehicle's cooling system. Mixing the orange and
green colored coolants will produce a brown coolant which may be a customer dissatisfier and will
not extend the service interval to that of DEX-COOL(R). Conventional silicated coolants offered by
GM Service and Parts Operations are green in color.
^ If available, use the approved cooling system flush and fill machine (available through the GM
Dealer Equipment Program) following the manufacturer's operating instructions.
^ If approved cooling systems flush and fill machine is not available, drain coolant and dispose of
properly following the draining procedures in appropriate Service Manual. Refill the system using
clear, drinkable water and run vehicle until thermostat opens. Repeat and run vehicle three (3)
times to totally remove old coolant or until drained coolant is almost clear. Once the system is
completely flushed, refill the cooling system to a 50%-60% concentration with a good quality
ethylene glycol base engine coolant, P/N 12378560, 1 gal (in Canada, use P/N 88862159 1 L),
conforming to GM specification 1825M, or recycled coolant conforming to GM specification 1825M,
following the refill procedures in the appropriate Service Manual.
If a Service Manual is not available, fill half the capacity of the system with 100% good quality
ethylene glycol base (green colored) engine coolant, P/N 12378560 1 gal., (in Canada, use P/N
88862159 1 L) conforming to GM specification 1825M. Then slowly add clear, drinkable water
(preferably distilled) to system until the level of the coolant mixture has reached the base of the
radiator neck. Wait two (2) minutes and recheck coolant level. If necessary, add clean water to
restore coolant to the appropriate level.
Once the system is refilled, recheck the coolant concentration using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. Concentration levels
should be between 50% and 65%.
Parts Information
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 2557
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Technical Service Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 2558
Radiator: Technical Service Bulletins Cooling - Radiator Repair/Replacement Guidelines
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 99-06-02-017
Date: October, 1999
INFORMATION
Subject: Radiator Repair/Replacement Guidelines
Models: 2000 and Prior Passenger Cars and Trucks
If repair of an aluminum/plastic radiator is required, it is recommended that the following guidelines
be followed:
For Vehicles Under Warranty
For aluminum/plastic radiators that have damage to the face of the core including bent fins,
punctures, cuts, leaking tubes or header tubes, the aluminum radiator core section should be
replaced with a new one. In these cases, if both of the plastic tanks are not damaged, they can be
reused with the new core. If one or both of the plastic tanks are damaged along with the core, it is
recommended that a complete new radiator assembly be installed.
Warranty repairs for leaks at the tank to header (gasket leaks), broken/cracked plastic tanks, cross
threaded or leaking oil coolers should be repaired without replacing the complete radiator. This
type of repair should be handled by the radiator repair facility in your area.
Many of these radiator repair facilities are members of the National Automotive Radiator Service
Association (NARSA) who follow industry and General Motors guidelines when repairing radiators.
These facilities have the special tools, tanks and pressurizing equipment needed to properly test
the repaired radiator prior to returning it to the dealership. Many of these facilities receive the repair
components directly from General Motors.
The sublet expense for a new radiator or the repair of the radiator under warranty should be
handled following normal procedures.
For Vehicles No Longer Under Warranty
The GM released epoxy repair kit referenced in previous publications is no longer available.
Repairs to the radiator, rather than replacement, is strictly at the owner's discretion.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Locations > Brace Radiator Support
Front Of Radiator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Locations > Brace Radiator Support > Page 2561
Rear Side Radiator Support, Coolant Fans
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Locations > Brace Radiator Support > Page 2562
LH Radiator Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Radiator > Component Information >
Locations > Page 2563
Radiator: Service and Repair
1. Disconnect battery ground cable, then remove air intake duct and resonator. 2. Drain coolant
into suitable containers through valve located in left radiator end tank. 3. Disconnect engine coolant
hoses from radiator, then remove engine cooling fans. 4. Disconnect and plug transmission cooler
and engine oil cooler lines, if equipped. 5. Disconnect coolant recovery reservoir, then remove
upper mounting panel if not equipped with mechanical fan. 6. Remove radiator. 7. Reverse
procedure to install, noting the following.
a. Ensure radiator is properly seated into lower mount cushions. b. Torque transmission cooler line
fittings to 17 ft. lbs. and if equipped with an engine oil cooler torque fittings to 18 ft. lbs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Relays and Modules - Cooling System >
Radiator Cooling Fan Motor Relay > Component Information > Locations
Radiator Cooling Fan Motor Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Relays and Modules - Cooling System >
Radiator Cooling Fan Motor Relay > Component Information > Locations > Page 2568
Engine Cooling Fan Relay Primary, Secondary
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Coolant Level Sensor > Component Information > Locations
Rear Side Radiator Support, Coolant Fans
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Engine - Coolant Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component
Information > Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Engine - Coolant Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component
Information > Specifications > Page 2577
Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Engine - Coolant Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component
Information > Specifications > Page 2578
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Engine - Coolant Temperature Sensor/Switch > Coolant Temperature Sensor/Switch (For Computer) > Component
Information > Specifications > Page 2579
Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Engine - Coolant Temperature Sensor/Switch > Radiator Cooling Fan Temperature Sensor / Switch > Component
Information > Locations
Radiator Cooling Fan Temperature Sensor / Switch: Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Sensors and Switches - Cooling System
> Engine - Coolant Temperature Sensor/Switch > Temperature Sensor (Gauge) > Component Information > Locations
Temperature Sensor (Gauge): Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Temperature Gauge > Component
Information > Description and Operation
Temperature Gauge: Description and Operation
DESCRIPTION
This temperature indicating system consists of a sending unit, located on the cylinder head,
electrical temperature gauge and an instrument voltage regulator.
OPERATION
As engine temperature increases or decreases, the resistance of the sending unit changes, in turn
controlling current flow through the gauge. When engine temperature is low sending unit resistance
is high, current flow through the gauge is restricted, and the gauge pointer remains against the stop
or moves very little. As engine temperature increases sending unit resistance decreases and
current flow through the gauge increases, resulting in increased pointer movement.
Troubleshooting for the electrical temperature indicating system is the same as for the electrical oil
pressure indicating system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Temperature Gauge > Component
Information > Description and Operation > Page 2589
Temperature Gauge: Testing and Inspection
Fig. 104 Chart 2: Engine Coolant Temperature Gauge Inoperative Or Inaccurate
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Temperature Warning Lamp/Indicator,
Engine Cooling > Component Information > Description and Operation
Temperature Warning Lamp/Indicator: Description and Operation
DESCRIPTION
If the red light is not lit when the engine is being cranked, check for a burned out bulb, an open in
the light circuit, or a defective ignition switch.
If the red light is lit when the engine is running, check the wiring between light and switch for a
ground, temperature switch defective, or overheated cooling system. As a test circuit to check
whether the red bulb is functioning properly, a wire which is connected to the ground terminal of the
ignition switch is tapped into its circuit. When the ignition is in the start engine cranking position, the
ground terminal is grounded inside the switch and the red bulb will be lit. When the engine is
started and the ignition switch is in the on position, the test circuit is opened and the bulb is then
controlled by the temperature switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Thermostat, Engine Cooling >
Component Information > Specifications
Thermostat: Specifications
Coolant Capacity, Qts...........................................................................................................................
............................................................................ [12] Radiator Cap Relief Pressure, psi....................
..............................................................................................................................................................
...... 15 Thermo. Opening Temp. °F......................................................................................................
........................................................................................ 185
[12] Less heavy duty radiator, 14.3 qts., w/ heavy duty radiator, 14.6 qts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Thermostat, Engine Cooling >
Component Information > Specifications > Page 2596
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Thermostat, Engine Cooling >
Component Information > Specifications > Page 2597
Thermostat: Testing and Inspection
Fig. 1 Thermostat.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Thermostat, Engine Cooling >
Component Information > Specifications > Page 2598
Thermostat: Service and Repair
Remove or Disconnect
1. Battery negative cable. 2. Air resonator and intake air duct. 3. Open coolant drain valve, located
in the left-hand radiator end tank, and drain engine coolant. 4. Close coolant drain valve. 5.
Radiator outlet hose and clamp from thermostat housing (14). 6. Bolts/screws (15). 7. Thermostat
housing (14). 8. Thermostat (17) and gasket (16).
Clean
^ Gasket surfaces of thermostat housing (14) and water pump (55).
Install or Connect
1. Thermostat (17) and new gasket (16). 2. Thermostat housing (14). 3. Bolts/screws (15).
Tighten Bolts/screws (15) to 28 Nm (21 lb. ft.).
4. Radiator outlet hose and clamp to thermostat housing (14). 5. Air intake duct and air resonator.
6. Add engine coolant. 7. Battery negative cable.
Inspect
^ For leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Water Pump > Component Information >
Service and Repair > Coolant Pump Driveshaft Assembly
Water Pump: Service and Repair Coolant Pump Driveshaft Assembly
This Article has been updated with TSB No. 57-61-28
COOLANT PUMP DRIVESHAFT ASSEMBLY
Fig. 23 Water Pump & Thermostat Replacement
TOOLS REQUIRED:
^ J 39243 Driven Gear Assembly Remover
^ J 41546 Driven Gear Assembly Installer
^ J 39089 Coolant Pump Shaft 0-Ring Protector
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Water Pump > Component Information >
Service and Repair > Coolant Pump Driveshaft Assembly > Page 2603
REMOVE OR DISCONNECT
1. Engine front cover assembly. 2. Rotate crankshaft assembly until timing marks punched on
crankshaft sprocket and camshaft sprocket are aligned. 3. Camshaft sprocket bolts/screws. 4.
Camshaft sprocket and timing chain assembly.
NOTICE: Do not turn the crankshaft assembly after the timing chain has been removed to prevent
damage to piston assemblies or valves.
5. Coolant pump bearing retainer bolts/screws and coolant pump driveshaft assembly using J
39243.
^ Remove and discard 0-ring from coolant pump drive-shaft assembly.
INSTALL OR CONNECT
1. Coolant pump drive shaft assembly using J 39092. 2. Coolant pump bearing retainer
bolts/screws.
TIGHTEN
^ Coolant pump bearing retainer bolts/screws to 12 Nm (108 lb. in.).
3. Camshaft sprocket and timing chain assembly.
^ Camshaft sprocket and coolant pump driveshaft gears must mesh, or damage to camshaft
retainer could occur.
4. Camshaft sprocket bolts/screws.
^ Make sure that camshaft and crankshaft timing marks align.
TIGHTEN
^ Camshaft sprocket bolts/screws to 28 Nm (21 lb. ft.).
5. New 0-ring to coolant pump driveshaft assembly using J 39089. 6. Engine front cover assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Water Pump > Component Information >
Service and Repair > Coolant Pump Driveshaft Assembly > Page 2604
Water Pump: Service and Repair Water/Coolant Pump
WATER PUMP REPLACEMENT
Fig. 17 Water Pump Replacement
REMOVAL PROCEDURE
The camshaft sprocket gear drives the water pump by using a drive shaft and coupling. Keep the
ignition wires connected to the distributor until the water pump is removed and all the coolant has
been drained.
1. Drain the engine coolant. 2. Remove the air cleaner resonator bracket nuts, if equipped with a
mechanical fan. 3. If the vehicle is equipped with a mechanical fan, remove the air cleaner
resonator by loosening the clamp and sliding the resonator off the studs. 4. If the vehicle is
equipped with a mechanical fan, remove the air intake duct. 5. If the vehicle is equipped with a
mechanical fan, remove the radiator fan upper shroud. 6. If the vehicle is equipped with a
mechanical fan, remove the fan belt from the tensioner. 7. If the vehicle is equipped with a
mechanical fan, remove the fan blade clutch nuts and the fan blade with the clutch attached. 8.
Remove the engine coolant and the heater hoses from the water pump. 9. If the vehicle is
equipped with a mechanical fan, remove the fan pulley.
10. If the vehicle is equipped with a mechanical fan, remove the coolant fan pulley bracket nuts. 11.
If the vehicle is equipped with a mechanical fan, remove the coolant fan pulley bracket. 12.
Remove the electrical connector from the coolant sensor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Water Pump > Component Information >
Service and Repair > Coolant Pump Driveshaft Assembly > Page 2605
13. Remove the secondary air injection pump and bracket. 14. Remove the water pump bolts and
the stud. 15. Remove the water pump and gaskets. 16. Remove the water pump driveshaft
coupling and the seals.
^ Discard the seals.
CLEAN
^ The water pump gasket surfaces.
^ The water pump bolts.
^ The coolant fan pulley bracket studs, if removed.
INSTALLATION PROCEDURE
1. Install the water pump driveshaft coupling and the new seals. 2. Install the water pump and the
gaskets. 3. Install the water pump bolts and the stud.
TIGHTEN
^ Bolts and the stud to 41 Nm (30 lb ft).
NOTICE: Use the correct fastener in the correct location. Replacement fasteners must be the
correct part number for that application. Fasteners requiring replacement or fasteners requiring the
use of thread locking compound or sealant are identified in the service procedure. Do not use
paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified.
These coatings affect fastener torque and joint clamping force and may damage the fastener. Use
the correct tightening sequence and specifications when installing fasteners in order to avoid
damage to parts and systems.
4. Install the secondary air injection pump and bracket. Refer to Refer to Air Pump in Engine
Controls. 5. Install the electrical connector to the coolant sensor. 6. Install the coolant fan pulley
bracket, if removed. 7. Install the coolant fan pulley bracket nuts, if removed.
TIGHTEN
^ Nuts to 50 Nm (37 lb ft).
8. Install the fan pulley, if removed. 9. Install the fan blade with the clutch attached and the nuts, if
removed.
TIGHTEN
^ Nuts to 26 Nm (19 lb ft).
10. Install the engine coolant hoses and the heater hoses to the water pump. 11. Install the fan belt
to the tensioner if the fan belt has been removed. 12. Install the radiator fan upper shroud if the
radiator fan upper shroud has been removed. 13. Install the air intake duct, if removed. 14. If the air
cleaner resonator has been removed, install the air cleaner resonator by sliding the resonator over
the studs and tightening the clamp until
snug.
15. Install the air cleaner resonator bracket nuts, if removed.
TIGHTEN
^ Nuts to 10 Nm (89 lb in).
16. Refill and bleed the cooling system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Cooling System > Water Pump > Component Information >
Service and Repair > Coolant Pump Driveshaft Assembly > Page 2606
Water Pump: Service and Repair Water Pump Disassembly
The OEM service manual does not provide water pump assembly service and repair information.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Exhaust System > Catalytic Converter > Component
Information > Locations
Catalytic Converter Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Exhaust System > Exhaust Manifold > Component
Information > Service and Repair
Exhaust Manifold: Service and Repair
Fig. 3 Exhaust Manifold Installation
1. Remove warm up three-way catalytic converter and gasket from exhaust manifold. 2. Remove oil
level indicator tube. 3. Remove secondary air injection pipe fitting from exhaust manifold. 4.
Remove generator rear lower braces. 5. Remove exhaust manifold bolts/screws, studs and
spacers, Fig. 3. 6. Remove exhaust manifold and gasket. 7. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Exhaust System > Muffler > Component Information >
Technical Service Bulletins > Customer Interest for Muffler: > 33-17-01A > Dec > 97 > Exhaust System - Paint Peeling from
Painted Muffler
Muffler: Customer Interest Exhaust System - Paint Peeling from Painted Muffler
File In Section: 10 - Body
Bulletin No.: 33-17-01A
Date: December, 1997
Subject: Paint Peeling from Muffler (New Repair Paint Available)
Models: 1993-98 Passenger Cars with Painted Mufflers
This bulletin is being revised to add additional model years. Please discard Corporate Bulletin
Number 33-17-01 (Section 10 - Body).
Condition
Some owners may experience paint peeling from the muffler.
Correction
Clean and repaint the affected area using the following procedure and product.
Important:
DO NOT REPLACE COMPONENTS TO REPAIR THIS CONDITION.
The exhaust system must be cold to begin this procedure.
Material Required: * Wabash Products # KB-318-HHHS, available in pints or quarts as ready to
spray material (no mixing required). Call Wabash Products, 1-800-326-7269 or 812-232-6097 for
pricing and shipping information.
Procedure
On a cold exhaust system:
1. Raise vehicle on hoist.
2. While supporting exhaust with a transmission jack, remove the rear exhaust system hangers and
lower the exhaust.
3. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
4. Wire brush the affected area to remove flaking paint and blow off with air.
5. Sand the affected area with # 80 to 150 grit sandpaper to remove rust, dirt or other
contaminants.
6. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
7. Tape off the rear lower body panels and exhaust pipes forward of mufflers to protect from
overspray.
8. Apply paint to affected area in several (6 to 8) thin coats (to prevent sags and runs) obtaining
approximately 1 mil paint coverage.
9. Raise exhaust system with jack, reinstall exhaust hangers, lower vehicle and remove from hoist.
^ Allow 30 minutes drying time.
10. In a well ventilated area, start engine and allow to idle for up to 30 minutes until paint is cured
and dry.
Important:
Some "smoking" will occur while curing the paint with the engine running.
The paint can be heated and cured while driving, but be careful not to get the exhaust system wet
during the first 30 minutes.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Exhaust System > Muffler > Component Information >
Technical Service Bulletins > Customer Interest for Muffler: > 33-17-01A > Dec > 97 > Exhaust System - Paint Peeling from
Painted Muffler > Page 2622
Labor Material
Operation Labor Time Allowance
A6150 0.6 hr - Single Exhaust GC
Add 0.2 hr - Dual Exhaust GC
Important:
While the above procedure and materials are correct for vehicles from 1993 to 1998, the Labor
Operation and Time Allowance only pertains to vehicles in the Warranty period.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Exhaust System > Muffler > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Muffler: > 33-17-01A > Dec > 97 > Exhaust System - Paint
Peeling from Painted Muffler
Muffler: All Technical Service Bulletins Exhaust System - Paint Peeling from Painted Muffler
File In Section: 10 - Body
Bulletin No.: 33-17-01A
Date: December, 1997
Subject: Paint Peeling from Muffler (New Repair Paint Available)
Models: 1993-98 Passenger Cars with Painted Mufflers
This bulletin is being revised to add additional model years. Please discard Corporate Bulletin
Number 33-17-01 (Section 10 - Body).
Condition
Some owners may experience paint peeling from the muffler.
Correction
Clean and repaint the affected area using the following procedure and product.
Important:
DO NOT REPLACE COMPONENTS TO REPAIR THIS CONDITION.
The exhaust system must be cold to begin this procedure.
Material Required: * Wabash Products # KB-318-HHHS, available in pints or quarts as ready to
spray material (no mixing required). Call Wabash Products, 1-800-326-7269 or 812-232-6097 for
pricing and shipping information.
Procedure
On a cold exhaust system:
1. Raise vehicle on hoist.
2. While supporting exhaust with a transmission jack, remove the rear exhaust system hangers and
lower the exhaust.
3. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
4. Wire brush the affected area to remove flaking paint and blow off with air.
5. Sand the affected area with # 80 to 150 grit sandpaper to remove rust, dirt or other
contaminants.
6. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
7. Tape off the rear lower body panels and exhaust pipes forward of mufflers to protect from
overspray.
8. Apply paint to affected area in several (6 to 8) thin coats (to prevent sags and runs) obtaining
approximately 1 mil paint coverage.
9. Raise exhaust system with jack, reinstall exhaust hangers, lower vehicle and remove from hoist.
^ Allow 30 minutes drying time.
10. In a well ventilated area, start engine and allow to idle for up to 30 minutes until paint is cured
and dry.
Important:
Some "smoking" will occur while curing the paint with the engine running.
The paint can be heated and cured while driving, but be careful not to get the exhaust system wet
during the first 30 minutes.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Engine, Cooling and Exhaust > Exhaust System > Muffler > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Muffler: > 33-17-01A > Dec > 97 > Exhaust System - Paint
Peeling from Painted Muffler > Page 2628
Labor Material
Operation Labor Time Allowance
A6150 0.6 hr - Single Exhaust GC
Add 0.2 hr - Dual Exhaust GC
Important:
While the above procedure and materials are correct for vehicles from 1993 to 1998, the Labor
Operation and Time Allowance only pertains to vehicles in the Warranty period.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Relays and Modules - Powertrain Management > Relays and
Modules - Computers and Control Systems > Engine Control Module > Component Information > Technical Service
Bulletins > Engine Controls - Aftermarket Accessory Usage
Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory
Usage
INFORMATION
Bulletin No.: 04-06-04-054B
Date: November 18, 2010
Subject: Info - Non-GM Parts and Accessories (Aftermarket)
Models:
2011 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed
Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate
Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System).
The recent rise and expansion of companies selling non-GM parts and accessories has made it
necessary to issue this reminder to dealers regarding GM's policy on the use and installation of
these aftermarket components.
When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to
use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs,
special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the
same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty
repairs, special policy repairs or any repairs paid for by GM.
During a warranty repair, if a GM original equipment part is not available through GM Customer
Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources,
the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order
the circumstances surrounding why non-GM parts were used. The dealer must give customers
written notice, prior to the sale or service, that such parts or accessories are not marketed or
warranted by General Motors.
It should also be noted that dealers modifying new vehicles and installing equipment, parts and
accessories obtained from sources not authorized by GM are responsible for complying with the
National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed
by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design
characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully
understand that non-GM approved parts may not have been validated, tested or certified for use.
This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part
failure occurs as the result of the installation or use of a non-GM approved part, the warranty will
not be honored.
A good example of non-authorized modification of vehicles is the result of an ever increasing
supply of aftermarket devices available to the customer, which claim to increase the horsepower
and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to
one or more of the following modifications:
- Propane injection
- Nitrous oxide injection
- Additional modules (black boxes) that connect to the vehicle wiring systems
- Revised engine calibrations downloaded for the engine control module
- Calibration modules which connect to the vehicle diagnostic connector
- Modification to the engine turbocharger waste gate
Although the installation of these devices, or modification of vehicle components, can increase
engine horsepower and torque, they may also negatively affect the engine emissions, reliability
and/or durability. In addition, other powertrain components, such as transmissions, universal joints,
drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the
installation of these devices.
General Motors does not support or endorse the use of devices or modifications that, when
installed, increase the engine horsepower and torque. It is because of these unknown stresses,
and the potential to alter reliability, durability and emissions performance, that GM has adopted a
policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining
warranty coverage, to the powertrain and driveline components whenever the presence of a
non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is
subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or
06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for
calibration verification.
These same policies apply as they relate to the use of non-GM accessories. Damage or failure
from the use or installation of a non-GM accessory will not be covered under warranty. Failure
resulting from the alteration or modification of the vehicle, including the cutting, welding or
disconnecting of the vehicle's original equipment parts and components will void the warranty.
Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal
inquiry at either the local, state or federal level that
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results from the alteration or modification of a vehicle using non-GM approved parts or accessories.
Dealers should be especially cautious of accessory companies that claim the installation of their
product will not void the factory warranty. Many times these companies have even given direction
on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from
finding out that is has been installed.
Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada
by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair
is to be made on the vehicle, even with the installation of such non-GM approved components, the
customer is to be made aware of General Motors position on this issue and is to sign the
appropriate goodwill documentation required by General Motors.
It is imperative for dealers to understand that by installing such devices, they are jeopardizing not
only the warranty coverage, but also the performance and reliability of the customer's vehicle.
Disclaimer
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Engine Control Module: Technical Service Bulletins PROM - Reprogram Using Off Board Program
Adapter
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 73-65-13
Date: March, 1997
INFORMATION
Subject: Reprogramming Capability using the Off Board Programming Adapter
Models: 1993-97 Passenger Cars and Trucks (Applicable Reprogrammable Vehicles)
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The General Motors vehicles contain Electronically Reprogrammable Devices (i.e. PCM, VCM,
ECM). These vehicles cannot be programmed through PROM replacement, however service
programming capability is available through the Tech 1/1A, Tech 2 and Techline terminals via
direct or remote programming.
The Environmental Protection Agency (EPA) has requested that all new vehicle manufacturers
ensure their dealers/retailers are aware that they are responsible for providing customers access to
reprogramming services at a reasonable cost and in a timely manner.
Although programming of controllers has become a common service practice at GM
dealers/retailers, the EPA has received reports from consumers and the aftermarket repair industry
that they were unable to purchase a new (programmed) Electronically Reprogrammable Device
(ERD) over-the-counter. As a result, on August 1, 1995, the Federal Government issued a
regulation requiring all manufacturers to make available reprogramming to the independent
aftermarket by December 1, 1997.
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Today, the Off Board Programming Adapter (OBPA) is used to reprogram ERD's sold
over-the-counter. For all practical purposes, the OBPA takes the place of the vehicle when the
vehicle is not available.
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The list of dealerships/retailers currently own the OBPA (see Attachments 1 - 3). These locations
are equipped to provide over-the-counter preprogrammed ERD's. The hardware required to
perform reprogramming in addition to the OBPA is a Techline terminal, Tech 1/1A and associated
cables and adapters. THE TECH 2 SHOULD NOT BE USED WITH THE OBPA AT THIS TIME
BECAUSE OF INADEQUATE OBPA GROUNDING.
The current OBPA can support reprogramming on all late model General Motor's vehicles except:
^ Premium V-8's
^ 1996 Diesel Truck
^ Cadillac Catera
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^ All 1997 programmable vehicles (requires use of the Tech 2)
A modification to the OBPA is being offered by Kent-Moore to support these additional vehicles and
to allow reprogramming using the Tech 2. The revisions to the OBPA for the Tech 2 is very
important as the Tech 2 is the only tool used for service programming for 1997 and future vehicles.
To have the modifications performed, contact Kent-Moore at (800) 345-2233. The revisions (part
number J 41207 REV-C) are free of charge for GM dealerships/retailers.
A dealership/retailer can purchase the OBPA by contacting Kent-Moore (part number J 41207-C).
Support on how to use the OBPA is provided by the Techline Customer Support Center (TCSC) at
(800) 828-6860 (English) or (800) 503-3222 (French).
If you need to purchase an OBPA and/or cable, contact Kent-Moore at (800) 345-2233. The OBPA
retails for $695.00 (includes all revisions 1-4) under part number J 41207-C.
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Engine Control Module: Specifications
Powertrain Control Module (PCM)
..............................................................................................................................................................
3 Nm (26 lb in.)
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PCM Location
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Engine Control Module: Connector Locations
Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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Engine Control Module: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Engine Control Module: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Engine Control Module: Connector Views
Powertrain Control Module (PCM): A
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Powertrain Control Module (PCM): B
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Powertrain Control Module (PCM): C
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Powertrain Control Module (PCM): D
Pinout Information
PCM Connectors
CAUTION: Do not backprobe Powertrain Control Module (PCM) connectors! The connectors are
sealed for operation in an underhood environment. Backprobing may damage the seal which could
eventually cause the connector to fail due to corrosion.
This information applies to the PCM connector charts in the next four images. These charts may be
used with the J 39700-A breakout box in conjunction with J 39700-110 and J 39700-140 cables
and high impedance digital multimeter J 39200 to obtain voltage present for each circuit listed.
Install the
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breakout box between the PCM connectors and the PCM. The breakout box PIN numbers
correspond with the PCM connector PIN numbers. Voltage may vary slightly, but should be very
close. Certain exceptions are called out in the chart legend below.
The following conditions must be met before checking typical voltages:
Key "ON":
^ DVM negative (black) lead connected to a known good ground.
^ Scan tool "NOT" installed.
^ All accessories "OFF."
^ Battery fully charged.
Engine Running:
^ All conditions listed above.
^ Engine at normal operating temperature.
^ Engine at idle/closed throttle/operating in "Closed Loop."
^ In park or neutral.
CHART LEGEND
(1) Less than .5 volt when system enabled. (2) Battery voltage for first two seconds with ignition
"ON." (3) Varies. (4) Varies with temperature. (5) Battery voltage when in gear. (6) Less than .5 volt
with brake pedal applied. (7) Battery voltage with A/C "ON." (8) Varies with altitude. (9) Less than
.5 volt with high power steering load. (*) Less than .5 volt.
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Connector "A"
RED
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Connector "B"
BLACK
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Connector "C"
GREY/CLEAR
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Connector "D"
BLUE
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Engine Control Module: Description and Operation
PCM Connectors
The Powertrain Control Module (PCM) is the control center of the fuel injection system. It
constantly looks at the information from various sensors and controls the systems that affect
vehicle performance. The PCM also performs a diagnostic function check of the system. It can
recognize operational problems and alert the driver through the Malfunction Indicator Lamp (MIL)
"Service Engine Soon" and store Diagnostic Trouble Code(s) (DTC) which identify the problem
areas to aid the technicians making repairs.
The PCM supplies 5 or 12 volts to power various sensors or switches. This is done through
resistances in the PCM which are so high in value that a test light will not light when connected to
the circuit. In some cases, even an ordinary shop voltmeter will not give an accurate reading
because its resistance is too low. Therefore, the use of a 10 megohm input impedance digital
voltmeter (J 39200) is required to assure accurate voltage readings.
Refer to Computers and Controls / System Diagnosis / Flow of Diagnosis / "Strategy Based
Diagnostics" for more information on using the diagnostic function of the PCM.
MEMORY
There are three types of memory storage within the PCM: Read Only Memory (ROM), Random
Access Memory (RAM) and Electrically Erasable Programmable Read Only Memory (EEPROM).
ROM Read Only Memory (ROM) is a permanent memory that is physically soldered to the circuit
boards within the PCM. The ROM contains the overall control programs. Once the ROM is
programmed, it cannot be changed. The ROM memory is non-erasable, and does not need power
to be retained.
RAM Random Access Memory (RAM) is the microprocessor "scratch pad." The processor can
write into, or read from this memory as needed. This memory is erasable and needs a constant
supply of voltage to be retained. If the voltage is lost, the memory is lost.
EEPROM Electrically Erasable Programmable Read Only Memory (EEPROM) is a permanent
memory that is physically soldered to the circuit boards within the PCM. The EEPROM contains the
overall control algorithms. The EEPROM can be reprogrammed by using the Tech 1 scan tool or
other Decline terminal/equipment.
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Component Tests and General Diagnostics
Engine Control Module: Component Tests and General Diagnostics
To display diagnostic trouble codes, use a Tech 1 (or equivalent scanner). Grounding the DLC will
NOT flash Diagnostic Trouble Code(s) (DTC), but will enable most outputs when the ignition is
"ON" engine "OFF." Grounding the Data Link Connector (DLC) while the engine is running will
cause the Malfunction Indicator Lamp (MIL) to flash to indicate "Open" or "Closed Loop. This is
referred to as Field Service Mode."
To clear the DTCs from memory use the Tech 1 or:
^ ignition "OFF."
^ Disconnect the # 2 fuse (located in the underhood electrical center) for 30 seconds.
Since the Powertrain Control Module (PCM) can have a failure which may affect only one circuit,
following the diagnostic procedures in this section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections or PCM is the cause of a problem and the
PCM is replaced the Knock Sensor (KS) module must be transferred to the new PCM and the new
PCM must then be programmed. If this does not correct the problem, one of the following may be
the reason:
^ There is a problem with the PCM terminal connections. The diagnostic chart will say PCM
connections or PCM. The terminals may have to be removed from the connector in order to check
them properly.
^ The problem is intermittent. This means that the problem is not present at the time the system is
being checked. In this case. Refer to Diagnosis by Symptom and make a careful physical
inspection of all portions of the system involved.
^ Shorted solenoid, relay coil, or harness. Solenoids and relays are turned "ON" and "OFF" by the
PCM using internal electronic switches called
"drivers."
A shorted solenoid, relay coil, or PCM harness will not damage the PCM but will cause the
component to be inoperative.
J 34636 or BT-8405 testers or equivalent provide a fast accurate means of checking for a shorted
coil or a short to battery voltage.
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Engine Control Module: Service and Repair
Removal
Hardware Removal
NOTE: To prevent internal Powertrain Control Module (PCM) damage, the ignition must be "OFF",
when disconnecting or reconnecting power to the PCM.
Remove or Disconnect:
1. Disconnect negative battery cable 2. Disconnect PCM mounting hardware 3. Disconnect PCM
electrical connectors 4. Remove PCM from engine compartment
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PCM With Knock Sensor Module
5. Remove PCM access cover
Removing Knock Sensor Module From PCM
6. Remove knock sensor module from PCM
Install or Connect:
1. Install knock sensor module and access cover 2. Install PCM in vehicle 3. Connect PCM
electrical connectors 4. Connect PCM mounting hardware 5. Connect negative battery cable
EEPROM Programming
CAUTION:The software/calibration used for PCM reprogramming must match the vehicle
application, or improper operation and/or damage may
occur.
^ Ensure battery is charged
^ Turn ignition "ON"
^ Ensure connections to the Data Link Connector (DLC) and battery/cigar lighter are secure
^ Follow the most current Decline terminal/equipment instructions
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PCM Reprogramming Failure
^ Check PCM connections
^ Check Decline terminal/equipment for latest software version
^ Repeat reprogramming procedures. If it fails again, replace the PCM. The replacement PCM
must be programmed.
PCM Functional Check
^ Refer to System Diagnosis / Diagnostic System Check.
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PCM With Knock Sensor Module
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Knock Sensor Module: Service and Repair
PCM With Knock Sensor Module
Removing Knock Sensor Module From PCM
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Powertrain Control Module (PCM) from mounting bracket (refer to
PCM removal). 3. Knock sensor (KS) module access cover. 4. Knock sensor module.
INSTALL OR CONNECT
NOTICE: To prevent possible electrostatic discharge damage to the PCM and KS module, Do Not
touch the connector pins or soldered components on the circuit board.
1. Knock senor module. 2. Access cover. 3. PCM to mounting bracket (refer to PCM installation). 4.
Negative battery cable.
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Air Injection Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
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Air Injection Pump Relay: Description and Operation
Chart C-6
The Powertrain Control Module (PCM) controls operation of the electric air pump relay which in
turn controls air availability to the air injection system. The PCM completes the ground to the coil
side of the relay. The relay in turn activates the electric air pump and the integral stop valve.
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Fuel Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
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Fuel Pump Relay: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Fuel Pump Relay: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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and Instructions > Page 2740
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Fuel Pump Relay: Description and Operation
When the ignition switch is turned to the "ON" position (before engaging starter), the energizes the
fuel pump relay for two seconds causing the fuel pump to pressurize the fuel system. If the
Powertrain Control Module (PCM) does not receive ignition reference pulses (engine cranking or
running) within two seconds, it shuts "OFF" the fuel pump relay, causing the fuel pump to stop.
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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Fuel Pump Relay: Service and Repair
Fuel Pump (Circuit Opening) Relay
REMOVE OR DISCONNECT
1. Underhood (U/H) electrical center cover. 2. Fuel pump relay.
INSTALL OR CONNECT
1. Fuel pump relay. 2. Underhood (U/H) electrical center cover.
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Modules - Ignition System > Ignition Control Module > Component Information > Specifications
Ignition Control Module: Specifications
Ignition Coil Assembly Bolt / Screw
...........................................................................................................................................................
25 Nm (18 lb ft.)
Ignition Coil Assembly Stud .................................................................................................................
...................................................... 25 Nm (18 lb ft.)
Ignition Coil Module Bolt / Screw
.............................................................................................................................................................
1.7 Nm (15 lb in.)
Replacement Coil to-Bracket Bolt / Screw
................................................................................................................................................. 2.8 Nm
(25 lb in.)
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Engine Left Side Upper
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> Page 2754
Ignition Control Module: Locations Ignition Module
Ignition Coil
Ignition Coil And Ignition Control Module
The Ignition Control Module is located on the ignition coil bracket assembly.
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Ignition Control Module: Description and Operation
Ignition Coil And Module Assembly
Ignition Coil And Module
The ignition coil/ignition control module assembly provides spark to the distributor assembly, timed
by signals from the ECM. Power (B+) for the ignition coil primary circuit and the ignition control
module is supplied by the ignition switch. The ECM combines the camshaft position information
supplied by the distributor with other system parameters and calculates the required spark advance
and coil dwell. The ECM signals the ignition control module, which turns on the primary current to
the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When
the primary current flow stops, high voltage induced in the ignition coil secondary winding becomes
the spark voltage for the spark plug. The spark voltage is delivered to the distributor assembly
through the coil output (secondary) wire, and then directed to the proper spark plug connector by
the distributor rotor.
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Ignition Control Module: Service and Repair
Ignition Coil
Ignition Coil And Ignition Control Module
Numbers used below refer to image caption.
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Four-terminal Powertrain Control
Module (PCM) connector at ignition coil module. 3. Ignition coil wiring connectors. 4. Ignition coil
harness.
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5. Studs (5). 6. Ignition coil / Ignition Control Module assembly (8).
^ Do not wipe silicone grease from bottom of ignition coil assembly (8) if it is to he reinstalled.
DISASSEMBLE
1. Coil (10) from brackets (13 and 14) by drilling out rivets (9). 2. Bolts/screws (12). 3. Ignition
control module (11).
NOTICE: If a new ignition coil assembly is to be installed, a package of silicone grease will be
included in the box. This grease is necessary for ignition coil assembly cooling.
ASSEMBLE
1. Spread silicone grease on metal face of ignition control module (11) and on bracket (13) where it
seats, and position ignition control module (11)
to bracket (13).
2. Bolts / screws (12).
Tighten ^
Bolts / screws (12) to 1.7 Nm (15 lb in.).
3. Coil (10) to brackets (13 and 14) using bolts / screws provided with replacement coil (10).
Tighten ^
Bolts / screws to 2.8 Nm (25 lb in.).
INSTALL OR CONNECT
1. Spread silicone grease on metal mounting face of ignition coil bracket (14) if necessary, and
position ignition coil / Ignition Control module
assembly (8) to cylinder head assembly.
2. Studs (5).
Tighten ^
Studs (5) to 25 Nm (18 lb ft.).
3. Ignition coil harness. 4. Ignition coil wiring connectors. 5. Four terminal PCM connector to
ignition coil module.
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Switches - Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Locations > Component
Locations
Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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Information and Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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MAF Sensor Circuit.
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Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
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Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information > Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
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Switches - Computers and Control Systems > Coolant Temperature Sensor/Switch (For Computer) > Component
Information > Specifications > Page 2839
Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
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Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
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Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
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Information and Instructions
Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information and Instructions > Page 2848
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Intake Air Temperature Sensor: Specifications Torque Valve
Torque Valve
Induction Air Sensor 44 in.lb
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Intake Air Temperature Sensor: Locations IAT Sensor
The Intake Air Temperature (IAT) sensor is located in the air ducting, just forward of the throttle
body assembly.
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Intake Air Temperature Sensor: Locations Intake Air Temperature (IAT) Sensor
Component Location - Pictorial View
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Component Location - Pictorial View
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Diagram Information and Instructions
Intake Air Temperature Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Intake Air Temperature Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Intake Air Temperature (IAT) Sensor Circuit.
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2918
Intake Air Temperature Sensor: Description and Operation
Engine Coolant Temperature (ECT) Sensor
The Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on
temperature). It is mounted in the air intake duct. Low temperature produces a high resistance and
high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the sensor through a resistor in
the PCM and measures the voltage. The voltage will be high when the intake air is cold, and low
when the intake manifold air is hot. By measuring the voltage, the PCM knows the intake air
temperature. A failure in the IAT sensor circuit should set either a DTC 23 or DTC 25.
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2919
Intake Air Temperature Sensor: Service and Repair
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Electrical connector. 3. Carefully remove sensor from air duct.
INSTALL OR CONNECT
1. Install sensor in engine. 2. Connect electrical connector. 3. Connect negative battery cable.
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Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
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Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
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> Page 2925
Engine Harness/U/Hood Electrical Center, Right Side
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Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor Circuit
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Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
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Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
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Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
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MAP Sensor Chart
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Manifold Pressure/Vacuum Sensor: Mechanical Specifications
Manifold Absolute Pressure (MAP) Bolt
...................................................................................................................................................... 6
Nm (50 lb in.)
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Manifold Pressure/Vacuum Sensor: Locations
MAP Sensor Location
Component Location - Pictorial View
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Diagram Information and Instructions
Manifold Pressure/Vacuum Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Manifold Pressure/Vacuum Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Map Sensor Circuit.
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Manifold Pressure/Vacuum Sensor: Description and Operation
MAP Sensor
The Manifold Absolute Pressure (MAP) sensor is a pressure sensor that measures changes in
intake manifold pressure. The pressure changes as a result of engine load and speed. The MAP
sensor converts this to a voltage output.
A closed throttle on engine coastdown would produce a relatively low MAP output while a
wide-open throttle would produce a high MAP output voltage. This high output voltage is produced
because the pressure inside the manifold is the same as outside the manifold, so you measure
100% of outside air pressure. Manifold Absolute Pressure (MAP) is inversely proportional to what
you would measure on a vacuum gage. When manifold pressure is high vacuum is low. The MAP
sensor is also used to measure barometric pressure under certain conditions which allows the
Powertrain Control Module (PCM) to automatically adjust for different altitudes.
The PCM sends a 5 volt reference signal to the MAP sensor. As the manifold pressure changes the
electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage the
PCM knows the manifold pressure. The PCM uses the MAP sensor to control ignition timing. The
MAP sensor is also used for speed density fuel management. When the PCM detects a
malfunction with the Mass Air Flow (MAF) sensor circuit the PCM will default to speed density.
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Manifold Pressure/Vacuum Sensor: Service and Repair
MAP Sensor Location
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Resonator. 3. Electrical connector. 4. Hold down bolts (2). 5. Sensor
from intake manifold.
INSTALL OR CONNECT
1. New sensor seal (lightly coated with clean engine oil). 2. Sensor into intake manifold. 3. Hold
down bolts. 4. Torque to 6 Nm (50 lb in). 5. Connect electrical connector. 6. Resonator. 7. Connect
negative battery cable.
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Oxygen Sensors - Silica Contamination
Oxygen Sensor: Technical Service Bulletins Oxygen Sensors - Silica Contamination
Model Year: 1981
Bulletin No: 81-I-37
File In Group: 60
Number: 11
Date: Feb. 81
Subject: Silica Contamination of Oxygen Sensors and Gelation of Oil.
Models Affected: All
Oxygen sensor performance can deteriorate if certain RTV silicone gasket materials are used.
Other RTV's when used with certain oils, may cause gelation of the oil. The degree of performance
severity depends on the type of RTV and application of the engine involved.
Therefore, when repairing engines where this item is involved, it is important to use either cork
composition gaskets or RTV silicone gasket material approved for such use. GMS (General Motors
Sealant) or equivalent material can be used. GMS is available through GMPD with the following
part numbers:
1052366 3 oz.
1052434 10.14 oz.
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Specifications
Oxygen Sensor Output
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Oxygen Sensor: Mechanical Specifications
Heated Oxygen Sensor (HO2S) ..........................................................................................................
......................................................... 41 Nm (30 lb ft.)
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Engine, Left Side Lower
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Lower Right Side Of Engine
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HO2S Location
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Oxygen Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oxygen Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Oxygen Sensor: Electrical Diagrams
Heated Oxygen Sensor (HO2S) Sensor Circuit.
Right Heated Oxygen Sensor Circuit.
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Oxygen Sensor: Description and Operation
HO2S Cutaway
Oxygen Sensor Element
The Heated Oxygen Sensor (HO2S) is essentially a small variable battery; it has the ability to
produce a low voltage signal that feeds information on engine exhaust oxygen content to the
Powertrain Control Module (PCM).
The PCM sends a reference signal of 450 mV. The reference signal serves to run the engine when
it is in "Open Loop" mode of operation. When the air/fuel ratio is correct the PCM displays 450 mV.
When the engine is operating with a rich air/fuel ratio, there is a reduction of free oxygen in the
exhaust stream and the oxygen voltage rises above the reference voltage.
The HO2S is constructed from a material (zirconia/platinum) that conducts electricity under certain
conditions. At operating temperature, 315°C (60o° F), the element becomes a semiconductor. A
platinum coating on the outer surface of the element stimulates further combustion of the exhaust
gases right
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at the surface and this helps keep the element up to the desired temperature. The HO2S has an
inter cavity which is filled with atmospheric (reference) air. The reference air has approximately
21% oxygen in it. In this electrical circuit this inter cavity is the positive (+) terminal. The outer
surface of the element is exposed to the exhaust gas stream. It is the negative (-) or ground
terminal. The oxygen concentration differences between the reference air and exhaust gases
produce small voltages.
A rich exhaust (excessive fuel) has almost no oxygen. When there is a large difference in the
amount of oxygen touching the inside and outside surfaces, there is more conduction, and the
sensor puts out a voltage signal above 600 mV. With lean exhaust (excessive oxygen) there is
about two percent oxygen in the exhaust. This is a smaller difference in oxygen from the outside
surfaces which results in less conduction and a voltage signal below 300 mV. The voltages are
monitored and used by the PCM to "fine tune" the air/fuel ratio to achieve the ideal mixture desired.
When the engine is running lean. the voltage drops below the reference voltage due to excess
oxygen in the exhaust stream. The HO2S provides the feedback information for the "Closed Loop"
operating mode of the fuel delivery system. The HO2S indicates to the PCM what is happening in
the exhaust. It does not cause things to happen. It is a type of gage: Low voltage output = lean
mixture = high oxygen content in exhaust; high voltage output = rich mixture = low oxygen content
in the exhaust.
An open Heated Oxygen Sensor (HO2S) circuit, should set Diagnostic Trouble Code (DTC) 13 or
63. A constant low voltage in the HO2S circuit could set a DTC 44 or 64. A constant high voltage in
the circuit should set a DTC 45 or 65. DTCs 44. 45. 64, or 65 could also be set as a result of fuel
system problems.
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Oxygen Sensor: Service and Repair
HO2S Location
CAUTION: The Heated Oxygen Sensor (HO2S) uses a permanently attached pigtail and
connector. This pigtail should not be removed from the oxygen sensor. Damage or removal of the
pigtail or connector could affect proper operation of the oxygen sensor.
^ Take care when handling the oxygen sensor. The in-line electrical connector and louvered end
must be kept free off grease, dirt or other contaminants. Also, avoid using cleaning solvents of any
type. Be careful not to subject the sensor to sharp impact.
REMOVAL:
NOTICE: The HO2S may be difficult to remove when engine temperature is below 48° C (120° F).
Excessive force may damage threads in exhaust pipe.
1. Disconnect the negative battery cable. 2. Raise vehicle. 3. Disconnect the oxygen sensor
electrical connector. 4. Carefully remove the oxygen sensor.
INSTALLATION:
NOTICE: A special anti-seize compound is used on the oxygen sensor threads. The compound
consists of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will
remain, making the sensor easier to remove. New or service sensors will already have the
compound applied to the threads. If a sensor is removed from an engine, and, if for any reason it is
to be reinstalled, the threads must have anti-seize compound applied before reinstallation.
1. Coat the threads of the HO2S with anti-seize compound P/N 5613695, or equivalent if
necessary. 2. Install the sensor in the engine, and tighten to 41 Nm (30 ft lb). 3. Connect the
electrical connector. 4. Lower vehicle. 5. Connect the negative battery cable.
NOTICE: The system has a learning ability which allows it to make corrections for minor variations
in the fuel system to improve driveability. When the battery is disconnected the computer's memory
is cleared and the learning process has to begin all over again. A change may be noticed in the
driving performance of the vehicle. To reset the vehicles learning ability, make sure the engine is at
operating temperature and operate the vehicle at part throttle, moderate acceleration, and idle
conditions, until normal performance returns.
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Left Front Of Engine
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Diagram Information and Instructions
Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Power Steering Pressure Switch Circuit.
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Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
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Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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Throttle Position Sensor: Locations
Component Location - Pictorial View
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Component Location - Pictorial View
Throttle Body
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Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Throttle Position Sensor Circuit.
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Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
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RH Side Of Steering Column
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RH Side Of Steering Column
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Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Rear Of Transmission
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Vehicle Speed Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Vehicle Speed Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Vehicle Speed Sensor: Description and Operation General Description
Vehicle Speed Sensor (2WD)
The Vehicle Speed Sensor (VSS) is a pulse counter type input that informs the Powertrain Control
Module (PCM) how fast the vehicle is being driven. The VSS system uses an inductive sensor
mounted in the tail housing of the transmission and a toothed reluctor wheel on the tail shaft. As
the reluctor rotates, the teeth alternately interfere with the magnetic field of the sensor creating an
induced voltage pulse.
The VSS produces an AC voltage signal that increases with vehicle speed. The PCM processes
this signal and sends it to the instrument panel, EVO module, chime module and cruise control
module on CKT 817. A malfunction in the VSS system could set Diagnostic Trouble Code (DTC) 24
or DTC 72.
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Vehicle Speed Sensor: Description and Operation Circuit Operation
The Speed Sensor Circuit consists of a magnetic type sensor and wiring. Gear teeth pressed on
the Transmission Output Shaft induce an alternating current in the sensor. This sensor generates a
sine wave output with a frequency proportional to vehicle speed. The Powertrain Control Module
(PCM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses
per mile at the DK GRN/WHT wire (CKT 817) which feeds the Turn Signal Alarm, Power Steering
Control Module, Instrument Cluster, Cruise Control Module and Radio (Chev only).
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Initial Inspection and Diagnostic Overview
Vehicle Speed Sensor: Initial Inspection and Diagnostic Overview
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
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Vehicle Speed Sensor: Symptom Related Diagnostic Procedures
Chart #1 Speedometer And Cruise Control Inoperative; Code 24 Not Set
Symptom Table
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Locations
Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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Information and Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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MAF Sensor Circuit.
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Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
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Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
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Fuel Pump/Engine Oil Pressure Indicator Switch
Rear Of Engine
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Fuel Pump/Engine Oil Pressure Indicator Switch > Page 3262
Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
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Diagram Information and Instructions
Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Fuel Pump Switch/Engine Oil Pressure Gage Sensor
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Fuel Pump Relay Circuit
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Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
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Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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3303
Throttle Position Sensor: Locations
Component Location - Pictorial View
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Component Location - Pictorial View
Throttle Body
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Information and Instructions
Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Throttle Position Sensor Circuit.
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Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
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Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
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Engine Harness/U/Hood Electrical Center, Right Side
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Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Page 3422
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor Circuit
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Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
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Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Sensors and Switches - Powertrain Management > Sensors and
Switches - Ignition System > Knock Sensor > Component Information > Diagrams > Page 3454
Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Fuel Pressure >
Diagnostic Connector - Fuel Pump > Component Information > Locations
Diagnostic Connector - Fuel Pump: Locations
The fuel pump test connector is located in the engine compartment near the A/C accumulator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Fuel Pressure >
Fuel Pressure Test Port > Component Information > Locations
Fuel Pressure Test Port
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Fuel Pressure >
Fuel Pressure Test Port > Component Information > Locations > Page 3463
Fuel Pressure Test Port: Service and Repair
Fuel Test Port Valve
CLEAN
^ Area around fuel pressure connection with GM X-3OA or equivalent.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery System / Service and Repair.
3. Fuel pressure connection valve assembly.
INSTALL OR CONNECT
1. Fuel pressure connection valve assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten
seconds. Again turn to "ON" position, and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air/Fuel Mixture >
System Information > Specifications
Air/Fuel Mixture: Specifications
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air/Fuel Mixture >
System Information > Specifications > Page 3467
Air/Fuel Mixture: Adjustments
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Idle Speed >
System Information > Specifications
Idle Speed: Specifications
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Idle Speed >
System Information > Specifications > Page 3471
Idle Speed: Adjustments
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Cleaner Fresh Air Duct/Hose > Component Information > Locations
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > Customer Interest for Air Filter
Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > Customer Interest for Air Filter
Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 3484
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Air
Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Air
Filter Element: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 3490
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > Page 3491
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > Page 3492
Air Filter Element: Service and Repair
Air Ducting
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Air Cleaner
Housing > Air Filter Element > Component Information > Technical Service Bulletins > Page 3493
REMOVE OR DISCONNECT
1. Loosen wing nuts at front of air cleaner housing. 2. Lift air cleaner lid, Mass Air Flow (MAF)
sensor and resonator as a unit. 3. Remove air filter element.
INSTALL OR CONNECT
1. Install air filter element. 2. Move air cleaner lid, MAF sensor and resonator into place. 3. Tighten
wing nuts. 4. Check clamps at MAF sensor and tighten if necessary. 5. Check joints between duct,
resonators and throttle body for possible air leaks. Repair if necessary.
NOTICE: If the Mass Air Flow (MAF) sensor is installed backwards, the system will go rich. An
arrow cast into the plastic portion of the sensor indicates proper air flow direction. The arrow must
point toward the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Fuel Filter > Fuel
Pressure Release > System Information > Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Firing Order >
Component Information > Specifications > Ignition Firing Order
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Firing Order >
Component Information > Specifications > Ignition Firing Order > Page 3502
Firing Order: Specifications Number 1 Cylinder Location
For number 1 cylinder locations, See: Ignition Timing/Number One Cylinder/Locations
See: Spark Plug Wire
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Ignition Timing >
Number One Cylinder > Component Information > Locations > Number 1 Cylinder Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Ignition Timing >
Timing Marks and Indicators > System Information > Locations > Crankshaft Rotation
Timing Marks and Indicators: Locations Crankshaft Rotation
Crankshaft Rotation (Typical Crankshaft Pulley)
Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the
generic image.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Ignition Timing >
Timing Marks and Indicators > System Information > Locations > Crankshaft Rotation > Page 3512
Timing Marks and Indicators: Locations Timing Marks
The ignition timing is completely controlled by the Powertrain Control Module (PCM). No timing
reference marks are provided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications
Spark Plug Wire: Specifications
Wire Harness Support Bolt / Screw
............................................................................................................................................................
40 Nm (30 lb ft.)
Wire Harness Support Channel Bolt / Screw (Right)
................................................................................................................................ 12 Nm (106 lb in.)
Wire Harness Support Channel Bolt/Screw (Left)
..................................................................................................................................... 12 Nm (106 lb
ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3516
Spark Plug Wire: Locations
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3517
Spark Plug Harness Routing
The spark plug wires run down both sides of the engine block under the exhaust manifolds.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3518
Spark Plug Wire: Description and Operation
The spark plug wire hamess assemblies use carbon impregnated cord conductors, encased in 8
mm (5 / 16-inch) diameter silicone jackets. The silicone jackets withstand very high temperatures
and also provide excellent insulation for the high voltage of the system. Silicone spark plug boots
form a tight seal to the spark plugs.
The material used to construct spark plug wires is very soft. This wire will withstand more heat and
carry a higher voltage, but chaffing and cutting become easier. The spark plug wires must be
routed correctly to prevent chafing or cutting. When removing a spark plug wire from a spark plug,
twist the boot on the spark plug one-half turn while pulling on the boot.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3519
Spark Plug Wire: Testing and Inspection
Inspect spark plug wires visually first for any cuts, burns, or damage. While engine is running,
inspect for any arcing to ground or other components. Use a spray bottle to lightly coat the spark
plug wires with water while observing idle quality. If idle quality diminishes or engine stalls, spark
plug wires should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3520
Spark Plug Wire: Service and Repair
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3521
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3522
Spark Plug Harness Routing
NOTICE: The boots should be twisted one-half turn while removing. Do not pull on the wire
harnesses to remove them from the spark plugs. Pull on the boots, or use a tool designed for this
purpose.
REMOVE OR DISCONNECT
Numbers included in this procedure refer to caption numbers in the included images.
1. Left bank spark plug wire boots from spark plugs. 2. Left bank spark plug wire harness support
channel bolts / screws (19) and channel. Rear bolt / screw (19) is located behind exhaust manifold
takedown. Loosen this bolt / screw using a 10 mm wrench then slide channel upward to disengage
from bolt / screw (19).
3. Left bank spark plug wire harness from clip (17) located behind air injection reactor (AIR) pump.
4. Right bank spark plug wire boots from spark plugs. 5. Air intake resonator.
With mechanical cooling fan: A. Upper radiator fan shroud, B. Loosen fan pulley nuts. C. Fan belt.
D. Mechanical fan and pulley. E. Mechanical fan pulley bracket nuts and bracket. F. Radiator outlet
pipe nuts from A/C compressor mounting studs.
6. Serpentine drive belt. 7. Raise and suitably support vehicle. 8. Transmission oil cooler line
support bolt / screw from accessory drive bracket. 9. Serpentine drive belt tensioner bolts/screws
and tensioner.
10. A/C compressor attaching bolts/screws
Reposition A/C compressor to provide access to front wire harness support (27).
11. Right wire harness support bolt / screw (28). 12. Right wire harness from support (27). 13. Left
and right bank spark plug wire harnesses (6) from distributor. 14. Left wire harness from clips (17,
20, 21 and 23).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug Wire
<--> [Ignition Cable] > Component Information > Specifications > Page 3523
^ Insert screwdriver into tab on top of clip to disengage.
15. Right wire harness from clips (16, 17, and 21).
^ Insert screwdriver into tab on top of clip to disengage.
NOTICE: When replacing spark plug wire harnesses (secondary wiring), route the wire harnesses
correctly and through the proper retainers. Failure to
route the wire harnesses properly can lead to radio ignition noise and cross-firing of the spark
plugs, or shorting of the leads to ground.
INSTALL OR CONNECT
1. Right wire harness to clips (16, 17 and 21). 2. Left wire harness to clips (17, 20, 21 and 23). 3.
Right wire harness to support (27). 4. Right wire harness support bolt / screw (28).
Tighten ^
Bolt / screw (28) to 40 Nm (30 lb ft.).
5. A/C compressor to bracket. 6. A/C compressor attaching bolts / screws and rear bracket nut.
Tighten A. A/C compressor bolts / screws to 50 Nm (37 lb ft.). B. A/C compressor rear bracket nut
to 41 Nm (30 lb ft.).
7. Serpentine drive belt tensioner and tensioner bolts / screws.
Tighten ^
Tensioner bolts / screws to 25 Nm (18 lb ft.).
8. Transmission oil cooler line support bolt / screw.
Tighten ^
Oil cooler line support bolt / screw to 1.9 Nm (17 lb in.).
9. Lower vehicle.
10. Serpentine drive belt.
With mechanical cooling fan: A. Radiator outlet pipe nuts from A/C compressor mounting studs.
Tighten ^
Radiator outlet pipe nuts to 16 Nm (12 lb ft.).
B. Mechanical fan pulley bracket nuts and bracket.
Tighten ^
Mechanical fan pulley bracket nuts to 50 Nm (37 lb .ft).
C. Mechanical fan pulley, fan and nuts.
^ Finger tighten only.
D. Fan belt.
Tighten ^
Mechanical fan nuts to 26 Nm (19 lb ft.).
E. Upper radiator fan shroud.
11. Air intake resonator. 12. Right bank spark plug wire boots to spark plugs. 13. Left bank spark
plug wire harness to clip (17) located behind AIR pump. 14. Left bank spark plug wire harness
support channel and bolts/screws (19). Rear bolt / screw (19) is located behind exhaust manifold
takedown.
Slide channel onto bolt / screw (19) then tighten using a 10 mm wrench.
15. Left bank spark plug wire harness boots to spark plugs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Distributor, Ignition
> Distributor Cap > Component Information > Specifications
Distributor Cap: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Distributor, Ignition
> Distributor Cap > Component Information > Service and Repair > Replacement
Distributor Cap: Service and Repair Replacement
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Distributor cap (30). 2. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten ^
Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
3. Vacuum harness assembly to distributor assembly. 4. Connect four-terminal PCM connector to
distributor. 5. Spark plug wire harness assemblies to distributor assembly. 6. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Distributor, Ignition
> Distributor Cap > Component Information > Service and Repair > Replacement > Page 3530
Distributor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Distributor, Ignition
> Ignition Rotor > Component Information > Specifications
Ignition Rotor: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Distributor Rotor Bolt / Screw ..............................................................................................................
....................................................... 0.7 Nm (6 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Distributor, Ignition
> Ignition Rotor > Component Information > Specifications > Page 3534
Ignition Rotor: Service and Repair
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30). 7. Rotor bolts / screws (32) using J 39998 or
equivalent. 8. Rotor assembly (32). 9. Distributor cover (33) and shield (34).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Shield (34) and distributor cover (33). 2. Rotor (32). 3. Rotor bolts / screws (31) using J 39998 or
equivalent.
Tighten ^
Rotor bolts / screws (31) to 0.7 Nm (61 lb in.).
4. Distributor cap (30). 5. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Distributor, Ignition
> Ignition Rotor > Component Information > Specifications > Page 3535
^ Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
6. Vacuum harness assembly to distributor assembly. 7. Connect four-terminal PCM connector to
distributor. 8. Spark plug wire harness assemblies to distributor assembly. 9. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications
Spark Plug: Specifications
Spark Plug Install Torque ....................................................................................................................
........................................................ 27 Nm (20 lb ft.)
Spark Plug Gap ...................................................................................................................................
........................................................ 1.27 mm (0.050")
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications > Page 3539
Spark Plug Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications > Page 3540
Spark Plug: Service Precautions
It is important that technicians wash their hands after handling coated spark plugs and before
smoking. The coating itself is a nonhazardous material and incidental contact will not cause any
adverse affects. However, exposure to polymer vapors (the result of a cigarette being coated from
handling, then burned) may cause flu like symptoms and should be avoided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications > Page 3541
Spark Plug ID
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications > Page 3542
Spark Plug: Description and Operation
Platinum-tipped, resistor-type, tapered-seat spark plugs are used on the engine assembly. No
gasket is used on these tapered-seat spark plugs. When replacing spark plugs, use only the type
specified.
Normal service is assumed to be a mixture of idling, slow speed, and high speed driving.
Occasional or intermittent high-speed driving is needed for good spark plug performance. It gives
increased combustion heat, burning away carbon or oxides that have built up from frequent idling,
or continual stop-and-go driving.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications > Page 3543
Spark Plug: Testing and Inspection
WORN OR DIRTY
Worn or dirty spark plugs may give satisfactory operation at idling speed, but frequently fail at
higher rpm. Faulty spark plugs may cause poor fuel economy, power loss, loss of speed, hard
starting and generally poor engine performance. Follow the scheduled maintenance service
recommendations to assure satisfactory spark plug performance.
NORMAL
Normal spark plug operation will result in brown to grayish - tan deposits appearing on the portion
of the spark plug that projects into the cylinder area. A small amount of red - brown, yellow, and
white powdery material may also be present on the insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels and lubricating oils with additives.
MISFIRING
Engine assemblies which are not running properly are often referred to as "misfiring." This means
the ignition spark is not igniting the fuel/air mixture at the proper time, While other ignition and fuel
system causes must also be considered, possible causes include ignition system conditions which
allow the spark voltage to reach ground in some other manner than by jumping across the air gap
at the tip of the spark plug, leaving the fuel/air mixture unburned. Misfiring may also occur when the
tip of the spark plug becomes overheated and ignites the mixture before the spark jumps. This is
referred to as "pre-ignition."
CARBON FOULING
Carbon fouling of the spark plug is indicated by dry, black carbon (soot) deposits on the portion of
the spark plug in the cylinder. Excessive idling and slow speeds under light engine loads can keep
the spark plug temperatures so low that these deposits are not burned off. Over - rich fuel mixtures
or poor ignition system output may also be the cause.
OIL FOULING
Oil fouling of the spark plug is indicated by wet oily deposits on the portion of the spark plug in the
cylinder. This may be caused by oil getting past worn piston rings. This condition also may occur
during break-in of new or newly overhauled engine assemblies.
DEPOSITS
Deposit fouling of the spark plug occurs when the normal red - brown, yellow or white deposits of
combustion by - products become sufficient to cause misfiring. In some cases, these deposits may
melt and form a shiny glaze on the insulator around the center electrode. If the fouling is found in
only one or two cylinders, valve stem clearances or intake valve seals may be allowing excess
lubricating oil to enter the cylinder, particularly if the deposits are heavier on the side of the spark
plug that was facing the intake valve.
CRACKED OR BROKEN
Cracked or broken insulators may be the result of improper installation or heat shock to the
insulator material. Upper insulators can be broken when a poorly fitting tool is used during
installation or removal, or when the park plug is hit from the outside. Cracks in the upper insulator
may be inside the shell and not visible. Also, the breakage may not cause problems until oil or
moisture penetrates the crack later.
A broken or cracked lower insulator tip (around the center electrode) may result from "heat shock"
(spark plug suddenly operating too hot).
"Heat shock" breakage in the lower insulator tip generally occurs during severe engine operating
conditions (high speeds or heavy loading) and may be caused by over - advanced timing or low
grade fuels. Heat shock refers to a rapid increase in the tip temperature that causes the insulator
material to crack.
Damage during gapping can happen if the gapping tool is pushed against the center electrode or
the insulator around it, causing the insulator to crack. When gapping a spark plug, make the
adjustment by only bending the ground side terminal, keeping the tool clear of other parts.
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Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Spark Plug >
Component Information > Specifications > Page 3544
Spark Plug: Service and Repair
Spark Plug Assembly
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Spark plug wire harness assemblies
from spark plugs. Refer to "Spark Plug Wire Harness Assembly Replacement" in this section.
^ Note positions of wires before removing.
NOTICE: Clean dirt and debris from spark plug recess areas.
3. Spark plugs from cylinder head assemblies.
NOTICE:
Be sure spark plugs thread smoothly into cylinder head assemblies and are fully seated. Cross threading or failing to fully seat spark plugs can cause overheating of spark plugs, exhaust blow-by,
or thread damage. Follow recommended torque specifications carefully. Over or under - tightening
can also cause severe damage to cylinder head assemblies or spark plug.
Check spark plug gap using a wire type gauge before installing. If spark plug gaps are not adjusted
correctly, engine idle quality may be seriously affected. A wire type gauge must be used (as
opposed to a flat feeler type gauge) to insure an accurate reading.
INSTALL OR CONNECT
1. Spark plugs to cylinder head assemblies.
Tighten ^
Spark plugs to 27 Nm (20 lb ft.).
2. Spark plug wire harness assemblies, routed properly as note during removal.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Compression
Check > System Information > Specifications
Compression Check: Specifications
The lowest reading cylinder should not be less than 70% of the highest and no cylinder reading
should be less than 689 kPa (100 psi). Perform compression test with engine at normal operating
temperature, spark plugs removed and throttle wide open.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Tune-up and Engine Performance Checks > Valve Clearance >
System Information > Specifications
Valve Clearance: Specifications
VALVE LASH
Turn rocker arm stud nut until all lash is eliminated (zero lash), then tighten nut additional turn in
1/4 turn increments.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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System Information > Specifications > Page 3551
Valve Clearance: Adjustments
Fig. 5 Valve Lash Adjustment
Adjust valves, Fig.5, with engine at normal operating temperature. Rotate engine until No. 1
cylinder is in position to fire. Adjust exhaust valves 1-3-4-8 and intake valves 1-2-5-7. Crank engine
one complete revolution, then adjust exhaust valves 2-5-6-7 and intake vales 3-4-6-8.
On all engines, the following procedure, performed with the engine running, should only be
performed if readjustment is required.
1. After engine has been warmed up to normal operating temperature, remove valve cover and
install a new valve cover gasket. 2. With engine running at idle speed, back off valve rocker arm
nut until rocker arm starts to clatter. 3. Turn rocker arm nut down slowly until clatter just stops. This
is the zero lash position. 4. Turn nut down 1/4 additional turn and pause 10 seconds until engine
runs smoothly. Repeat additional 1/4 turns, pausing 10 seconds each time,
until nut has been turned down the number of turns listed in "Valve Clearance Specifications chart
from the zero lash position. This preload adjustment must be done slowly to allow lifter to adjust
itself to prevent the possibility of interference between valve head and top of piston, which might
result in internal damage and/or bent push rods. Noisy lifters should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > A/C Signal > Component
Information > Locations
A/C Signal: Locations
Relay Location
The A/C clutch relay is located in the underhood electrical center.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > A/C Signal > Component
Information > Description and Operation > A/C Refrigerant Pressure Signal
A/C Signal: Description and Operation A/C Refrigerant Pressure Signal
This signal is used by the Powertrain Control Module (PCM) to enable cooling fans when
compressor head pressure reaches about 89 psi. If a fault is present in the A/C refrigerant pressure
sensor circuit, a Diagnostic Trouble Code (DTC) 66 and 67 will set, and the A/C clutch would be
disabled.
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Information > Description and Operation > A/C Refrigerant Pressure Signal > Page 3558
A/C Signal: Description and Operation A/C Request Signal
When the heater and A/C control is placed in the A/C Mode, a request signal is sent to the PCM.
The PCM will then energize the A/C clutch relay, unless abnormally high or low A/C pressure is
detected by the A/C refrigerant pressure sensor. The PCM will also turn the cooling fans "ON"
when A/C is requested. The A/C clutch relay is controlled by the PCM so that the PCM can
increase idle speed before turning "ON" the clutch or disable the clutch during WOT, and high
coolant temperature.
This system consists of a heater and A/C control, A/C pressure cycling switch, an A/C refrigerant
pressure sensor, an A/C clutch relay, the compressor clutch, and the PCM. The A/C refrigerant
pressure cycling switch is closed when there is sufficient system pressure (depending on
refrigerant charge (R134a) and ambient temperature).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > A/C Signal > Component
Information > Description and Operation > Page 3559
A/C Signal: Testing and Inspection
The Powertrain Control Module (PCM) will energize the A/C clutch whenever the engine is running
less than 3800 RPM and A/C has been requested unless any of the following conditions are met:
^ Wide Open Throttle (WOT).
^ A/C head pressure greater than 429 psi or less than 0 psi (as determined by the A/C refrigerant
pressure sensor),
^ Low ignition voltage.
^ Engine speed greater than 5250 RPM for 30 seconds.
^ Engine Coolant Temperature (ECT) greater than 124°C (255°F).
Chart C-10 should be used for diagnosing the electrical portion of the A/C circuit. Refer to Heating
and Air Conditioning for diagnosing the refrigerant portion of the system.
The Tech 1 will be used in diagnosing the system, as it has the ability to display the A/C request
input to the PCM, A/C compressor status, A/C system pressure, as well as displaying when the
PCM has commanded the A/C clutch "ON."
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Locations > Component Locations
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Locations > Component Locations > Page 3564
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 3567
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Component Information > Diagrams > Diagram Information and Instructions > Page 3568
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 3569
Fig.1-Symbols (Part 1 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 3570
Fig.2-Symbols (Part 2 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 3571
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 3572
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 3573
Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Component Information > Diagrams > Diagram Information and Instructions > Page 3574
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 3575
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Component Information > Diagrams > Diagram Information and Instructions > Page 3576
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Component Information > Diagrams > Diagram Information and Instructions > Page 3596
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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MAF Sensor Circuit.
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Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Intake Air Temperature
Sensor > Component Information > Specifications
Intake Air Temperature Sensor: Specifications Torque Valve
Torque Valve
Induction Air Sensor 44 in.lb
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Sensor > Component Information > Locations > IAT Sensor
Intake Air Temperature Sensor: Locations IAT Sensor
The Intake Air Temperature (IAT) sensor is located in the air ducting, just forward of the throttle
body assembly.
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Intake Air Temperature Sensor: Locations Intake Air Temperature (IAT) Sensor
Component Location - Pictorial View
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Component Location - Pictorial View
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Intake Air Temperature Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Intake Air Temperature Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3641
Intake Air Temperature (IAT) Sensor Circuit.
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Intake Air Temperature Sensor: Description and Operation
Engine Coolant Temperature (ECT) Sensor
The Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on
temperature). It is mounted in the air intake duct. Low temperature produces a high resistance and
high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the sensor through a resistor in
the PCM and measures the voltage. The voltage will be high when the intake air is cold, and low
when the intake manifold air is hot. By measuring the voltage, the PCM knows the intake air
temperature. A failure in the IAT sensor circuit should set either a DTC 23 or DTC 25.
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Intake Air Temperature Sensor: Service and Repair
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Electrical connector. 3. Carefully remove sensor from air duct.
INSTALL OR CONNECT
1. Install sensor in engine. 2. Connect electrical connector. 3. Connect negative battery cable.
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Component Information > Diagrams > Diagram Information and Instructions
Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Camshaft Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 3673
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Coolant Temperature
Sensor/Switch (For Computer) > Component Information > Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
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Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
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Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
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Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Crankshaft Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions
Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Component Information > Diagrams > Diagram Information and Instructions > Page 3691
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Data Link Connector >
Component Information > Locations > Component Locations
Data Link Connector: Component Locations
The Data Link Connector (DLC) is located under the dashboard in the center of the vehicle.
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Center Of Instrument Panel Wiring
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Data Link Connector: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Data Link Connector: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Component Information > Diagrams > Diagram Information and Instructions > Page 3755
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Component Information > Diagrams > Diagram Information and Instructions > Page 3756
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 3757
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Component Information > Diagrams > Diagram Information and Instructions > Page 3758
Data Link Connector: Connector Views
Data Link Connector (DLC)
DLC
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Component Information > Diagrams > Diagram Information and Instructions > Page 3759
Data Link Connector (DLC): Pin Assignment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Data Link Connector >
Component Information > Description and Operation > Circuit Operation
Data Link Connector: Description and Operation Circuit Operation
The Data Stream (on the 800 CKT) uses a 8192 Baud Rate During normal vehicle operation the
Powertrain Control Module (PCM) serves as the "Master" Module. When using the Tech-1 the
Tech-1, will serve as the "Master" Module and interrogate any Module on the 800 CKT.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Description and Operation > Circuit Operation > Page 3762
Data Link Connector: Description and Operation General Description
DLC
DATA LINK CONNECTOR (DLC)
The provision for communicating from vehicle to scanner is the DLC. It is usually located under the
instrument panel and is sometimes covered by a plastic cover labeled "DIAGNOSTIC
CONNECTOR." It is used in the assembly plant to receive information in checking that the engine
is operating properly before it leaves the plant. The connector can also be used by the service
technician to identify Powertrain Control Module ( PCM) stored trouble codes.
NOTE: There are two different types of DLC connectors, a 12 terminal and a 16 terminal. ONLY the
12 terminal connector which is equipped with a terminal "B" will flash DTC codes through the
"Service Engine Soon" / Malfunction Indicator Lamp (MIL).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage
Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory
Usage
INFORMATION
Bulletin No.: 04-06-04-054B
Date: November 18, 2010
Subject: Info - Non-GM Parts and Accessories (Aftermarket)
Models:
2011 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed
Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate
Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System).
The recent rise and expansion of companies selling non-GM parts and accessories has made it
necessary to issue this reminder to dealers regarding GM's policy on the use and installation of
these aftermarket components.
When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to
use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs,
special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the
same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty
repairs, special policy repairs or any repairs paid for by GM.
During a warranty repair, if a GM original equipment part is not available through GM Customer
Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources,
the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order
the circumstances surrounding why non-GM parts were used. The dealer must give customers
written notice, prior to the sale or service, that such parts or accessories are not marketed or
warranted by General Motors.
It should also be noted that dealers modifying new vehicles and installing equipment, parts and
accessories obtained from sources not authorized by GM are responsible for complying with the
National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed
by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design
characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully
understand that non-GM approved parts may not have been validated, tested or certified for use.
This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part
failure occurs as the result of the installation or use of a non-GM approved part, the warranty will
not be honored.
A good example of non-authorized modification of vehicles is the result of an ever increasing
supply of aftermarket devices available to the customer, which claim to increase the horsepower
and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to
one or more of the following modifications:
- Propane injection
- Nitrous oxide injection
- Additional modules (black boxes) that connect to the vehicle wiring systems
- Revised engine calibrations downloaded for the engine control module
- Calibration modules which connect to the vehicle diagnostic connector
- Modification to the engine turbocharger waste gate
Although the installation of these devices, or modification of vehicle components, can increase
engine horsepower and torque, they may also negatively affect the engine emissions, reliability
and/or durability. In addition, other powertrain components, such as transmissions, universal joints,
drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the
installation of these devices.
General Motors does not support or endorse the use of devices or modifications that, when
installed, increase the engine horsepower and torque. It is because of these unknown stresses,
and the potential to alter reliability, durability and emissions performance, that GM has adopted a
policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining
warranty coverage, to the powertrain and driveline components whenever the presence of a
non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is
subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or
06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for
calibration verification.
These same policies apply as they relate to the use of non-GM accessories. Damage or failure
from the use or installation of a non-GM accessory will not be covered under warranty. Failure
resulting from the alteration or modification of the vehicle, including the cutting, welding or
disconnecting of the vehicle's original equipment parts and components will void the warranty.
Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal
inquiry at either the local, state or federal level that
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Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3767
results from the alteration or modification of a vehicle using non-GM approved parts or accessories.
Dealers should be especially cautious of accessory companies that claim the installation of their
product will not void the factory warranty. Many times these companies have even given direction
on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from
finding out that is has been installed.
Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada
by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair
is to be made on the vehicle, even with the installation of such non-GM approved components, the
customer is to be made aware of General Motors position on this issue and is to sign the
appropriate goodwill documentation required by General Motors.
It is imperative for dealers to understand that by installing such devices, they are jeopardizing not
only the warranty coverage, but also the performance and reliability of the customer's vehicle.
Disclaimer
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Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3768
Engine Control Module: Technical Service Bulletins PROM - Reprogram Using Off Board Program
Adapter
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 73-65-13
Date: March, 1997
INFORMATION
Subject: Reprogramming Capability using the Off Board Programming Adapter
Models: 1993-97 Passenger Cars and Trucks (Applicable Reprogrammable Vehicles)
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Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3769
The General Motors vehicles contain Electronically Reprogrammable Devices (i.e. PCM, VCM,
ECM). These vehicles cannot be programmed through PROM replacement, however service
programming capability is available through the Tech 1/1A, Tech 2 and Techline terminals via
direct or remote programming.
The Environmental Protection Agency (EPA) has requested that all new vehicle manufacturers
ensure their dealers/retailers are aware that they are responsible for providing customers access to
reprogramming services at a reasonable cost and in a timely manner.
Although programming of controllers has become a common service practice at GM
dealers/retailers, the EPA has received reports from consumers and the aftermarket repair industry
that they were unable to purchase a new (programmed) Electronically Reprogrammable Device
(ERD) over-the-counter. As a result, on August 1, 1995, the Federal Government issued a
regulation requiring all manufacturers to make available reprogramming to the independent
aftermarket by December 1, 1997.
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Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3770
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3771
Today, the Off Board Programming Adapter (OBPA) is used to reprogram ERD's sold
over-the-counter. For all practical purposes, the OBPA takes the place of the vehicle when the
vehicle is not available.
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Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3772
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3773
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3774
The list of dealerships/retailers currently own the OBPA (see Attachments 1 - 3). These locations
are equipped to provide over-the-counter preprogrammed ERD's. The hardware required to
perform reprogramming in addition to the OBPA is a Techline terminal, Tech 1/1A and associated
cables and adapters. THE TECH 2 SHOULD NOT BE USED WITH THE OBPA AT THIS TIME
BECAUSE OF INADEQUATE OBPA GROUNDING.
The current OBPA can support reprogramming on all late model General Motor's vehicles except:
^ Premium V-8's
^ 1996 Diesel Truck
^ Cadillac Catera
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Component Information > Technical Service Bulletins > Engine Controls - Aftermarket Accessory Usage > Page 3775
^ All 1997 programmable vehicles (requires use of the Tech 2)
A modification to the OBPA is being offered by Kent-Moore to support these additional vehicles and
to allow reprogramming using the Tech 2. The revisions to the OBPA for the Tech 2 is very
important as the Tech 2 is the only tool used for service programming for 1997 and future vehicles.
To have the modifications performed, contact Kent-Moore at (800) 345-2233. The revisions (part
number J 41207 REV-C) are free of charge for GM dealerships/retailers.
A dealership/retailer can purchase the OBPA by contacting Kent-Moore (part number J 41207-C).
Support on how to use the OBPA is provided by the Techline Customer Support Center (TCSC) at
(800) 828-6860 (English) or (800) 503-3222 (French).
If you need to purchase an OBPA and/or cable, contact Kent-Moore at (800) 345-2233. The OBPA
retails for $695.00 (includes all revisions 1-4) under part number J 41207-C.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Technical Service Bulletins > Page 3776
Engine Control Module: Specifications
Powertrain Control Module (PCM)
..............................................................................................................................................................
3 Nm (26 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Locations > Component Locations
PCM Location
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Component Information > Locations > Component Locations > Page 3779
Engine Control Module: Connector Locations
Powertrain Control Module (PCM)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Locations > Component Locations > Page 3780
Powertrain Control Module (PCM)
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Component Information > Locations > Component Locations > Page 3781
Powertrain Control Module (PCM)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Locations > Component Locations > Page 3782
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Engine Control Module >
Component Information > Diagrams > Diagram Information and Instructions
Engine Control Module: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Component Information > Diagrams > Diagram Information and Instructions > Page 3785
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Component Information > Diagrams > Diagram Information and Instructions > Page 3786
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Component Information > Diagrams > Diagram Information and Instructions > Page 3787
Fig.1-Symbols (Part 1 Of 3)
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Component Information > Diagrams > Diagram Information and Instructions > Page 3788
Fig.2-Symbols (Part 2 Of 3)
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Component Information > Diagrams > Diagram Information and Instructions > Page 3789
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Component Information > Diagrams > Diagram Information and Instructions > Page 3790
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Component Information > Diagrams > Diagram Information and Instructions > Page 3791
Engine Control Module: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Component Information > Diagrams > Diagram Information and Instructions > Page 3816
Engine Control Module: Connector Views
Powertrain Control Module (PCM): A
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Powertrain Control Module (PCM): B
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Powertrain Control Module (PCM): C
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Powertrain Control Module (PCM): D
Pinout Information
PCM Connectors
CAUTION: Do not backprobe Powertrain Control Module (PCM) connectors! The connectors are
sealed for operation in an underhood environment. Backprobing may damage the seal which could
eventually cause the connector to fail due to corrosion.
This information applies to the PCM connector charts in the next four images. These charts may be
used with the J 39700-A breakout box in conjunction with J 39700-110 and J 39700-140 cables
and high impedance digital multimeter J 39200 to obtain voltage present for each circuit listed.
Install the
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breakout box between the PCM connectors and the PCM. The breakout box PIN numbers
correspond with the PCM connector PIN numbers. Voltage may vary slightly, but should be very
close. Certain exceptions are called out in the chart legend below.
The following conditions must be met before checking typical voltages:
Key "ON":
^ DVM negative (black) lead connected to a known good ground.
^ Scan tool "NOT" installed.
^ All accessories "OFF."
^ Battery fully charged.
Engine Running:
^ All conditions listed above.
^ Engine at normal operating temperature.
^ Engine at idle/closed throttle/operating in "Closed Loop."
^ In park or neutral.
CHART LEGEND
(1) Less than .5 volt when system enabled. (2) Battery voltage for first two seconds with ignition
"ON." (3) Varies. (4) Varies with temperature. (5) Battery voltage when in gear. (6) Less than .5 volt
with brake pedal applied. (7) Battery voltage with A/C "ON." (8) Varies with altitude. (9) Less than
.5 volt with high power steering load. (*) Less than .5 volt.
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Connector "A"
RED
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Connector "B"
BLACK
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Connector "C"
GREY/CLEAR
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Connector "D"
BLUE
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Engine Control Module: Description and Operation
PCM Connectors
The Powertrain Control Module (PCM) is the control center of the fuel injection system. It
constantly looks at the information from various sensors and controls the systems that affect
vehicle performance. The PCM also performs a diagnostic function check of the system. It can
recognize operational problems and alert the driver through the Malfunction Indicator Lamp (MIL)
"Service Engine Soon" and store Diagnostic Trouble Code(s) (DTC) which identify the problem
areas to aid the technicians making repairs.
The PCM supplies 5 or 12 volts to power various sensors or switches. This is done through
resistances in the PCM which are so high in value that a test light will not light when connected to
the circuit. In some cases, even an ordinary shop voltmeter will not give an accurate reading
because its resistance is too low. Therefore, the use of a 10 megohm input impedance digital
voltmeter (J 39200) is required to assure accurate voltage readings.
Refer to Computers and Controls / System Diagnosis / Flow of Diagnosis / "Strategy Based
Diagnostics" for more information on using the diagnostic function of the PCM.
MEMORY
There are three types of memory storage within the PCM: Read Only Memory (ROM), Random
Access Memory (RAM) and Electrically Erasable Programmable Read Only Memory (EEPROM).
ROM Read Only Memory (ROM) is a permanent memory that is physically soldered to the circuit
boards within the PCM. The ROM contains the overall control programs. Once the ROM is
programmed, it cannot be changed. The ROM memory is non-erasable, and does not need power
to be retained.
RAM Random Access Memory (RAM) is the microprocessor "scratch pad." The processor can
write into, or read from this memory as needed. This memory is erasable and needs a constant
supply of voltage to be retained. If the voltage is lost, the memory is lost.
EEPROM Electrically Erasable Programmable Read Only Memory (EEPROM) is a permanent
memory that is physically soldered to the circuit boards within the PCM. The EEPROM contains the
overall control algorithms. The EEPROM can be reprogrammed by using the Tech 1 scan tool or
other Decline terminal/equipment.
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Engine Control Module: Component Tests and General Diagnostics
To display diagnostic trouble codes, use a Tech 1 (or equivalent scanner). Grounding the DLC will
NOT flash Diagnostic Trouble Code(s) (DTC), but will enable most outputs when the ignition is
"ON" engine "OFF." Grounding the Data Link Connector (DLC) while the engine is running will
cause the Malfunction Indicator Lamp (MIL) to flash to indicate "Open" or "Closed Loop. This is
referred to as Field Service Mode."
To clear the DTCs from memory use the Tech 1 or:
^ ignition "OFF."
^ Disconnect the # 2 fuse (located in the underhood electrical center) for 30 seconds.
Since the Powertrain Control Module (PCM) can have a failure which may affect only one circuit,
following the diagnostic procedures in this section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections or PCM is the cause of a problem and the
PCM is replaced the Knock Sensor (KS) module must be transferred to the new PCM and the new
PCM must then be programmed. If this does not correct the problem, one of the following may be
the reason:
^ There is a problem with the PCM terminal connections. The diagnostic chart will say PCM
connections or PCM. The terminals may have to be removed from the connector in order to check
them properly.
^ The problem is intermittent. This means that the problem is not present at the time the system is
being checked. In this case. Refer to Diagnosis by Symptom and make a careful physical
inspection of all portions of the system involved.
^ Shorted solenoid, relay coil, or harness. Solenoids and relays are turned "ON" and "OFF" by the
PCM using internal electronic switches called
"drivers."
A shorted solenoid, relay coil, or PCM harness will not damage the PCM but will cause the
component to be inoperative.
J 34636 or BT-8405 testers or equivalent provide a fast accurate means of checking for a shorted
coil or a short to battery voltage.
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Engine Control Module: Service and Repair
Removal
Hardware Removal
NOTE: To prevent internal Powertrain Control Module (PCM) damage, the ignition must be "OFF",
when disconnecting or reconnecting power to the PCM.
Remove or Disconnect:
1. Disconnect negative battery cable 2. Disconnect PCM mounting hardware 3. Disconnect PCM
electrical connectors 4. Remove PCM from engine compartment
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PCM With Knock Sensor Module
5. Remove PCM access cover
Removing Knock Sensor Module From PCM
6. Remove knock sensor module from PCM
Install or Connect:
1. Install knock sensor module and access cover 2. Install PCM in vehicle 3. Connect PCM
electrical connectors 4. Connect PCM mounting hardware 5. Connect negative battery cable
EEPROM Programming
CAUTION:The software/calibration used for PCM reprogramming must match the vehicle
application, or improper operation and/or damage may
occur.
^ Ensure battery is charged
^ Turn ignition "ON"
^ Ensure connections to the Data Link Connector (DLC) and battery/cigar lighter are secure
^ Follow the most current Decline terminal/equipment instructions
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PCM Reprogramming Failure
^ Check PCM connections
^ Check Decline terminal/equipment for latest software version
^ Repeat reprogramming procedures. If it fails again, replace the PCM. The replacement PCM
must be programmed.
PCM Functional Check
^ Refer to System Diagnosis / Diagnostic System Check.
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[Idle Speed/Throttle Actuator - Electronic] > Component Information > Specifications
Idle Air Control (IAC): Specifications
Idle Air Control (IAC) Valve Screws
............................................................................................................................................................
3 Nm (27 lb in.)
IAC Valve/Coolant Cover Assembly Screws
............................................................................................................................................. 3.2 Nm
(28 lb in.)
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Idle Air Control (IAC): Locations
Component Location - Pictorial View
Throttle Body
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Component Location - Pictorial View
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Idle Air Control (IAC): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Page 3838
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Page 3839
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Page 3840
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Idle Air Control (IAC): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Idle Air Control (IAC) Valve
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Idle Air Control (IAC) Circuit
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Idle Air Control (IAC): Description and Operation
Throttle Body
IAC Valve Flow
The purpose of the Idle Air Control (IAC) valve assembly is to control engine idle speed while
preventing stalls do to changes in engine load.
The IAC valve, mounted in the throttle body, controls a portion of the bypass air. An orifice located
between the throttle valves also supplies a constant amount of bypass air. By moving a conical
valve known as a pintle, IN, towards the seat (to decrease air flow) or OUT, away from the seat (to
increase air flow) a controlled amount of air can be bypassed. If engine speed is too low, more air
is bypassed to increase RPM. If engine speed is too high, less air is bypassed to decrease RPM.
The Powertrain Control Module (PCM) moves the IAC valve in small steps, called counts. These
can be measured and displayed by a scan tool which plugs into the Data Link Connector (DLC).
During idle, the proper position of the IAC valve is calculated by the PCM, based on battery
voltage, coolant temperature, engine load, and engine RPM. If the RPM drops below specification
and the throttle valve is closed, the PCM senses a near stall condition and calculates a new valve
position to prevent stalling.
^ Engine idle speed is a function of total air flow into the engine based on IAC valve pintle position
+ crankcase ventilation valve flow + throttle
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valve opening + bypass orifice air flow + calibrated vacuum loss through accessories.
^ Controlled idle speed is programmed into the PCM, which determines the correct lAC valve pintle
position to maintain the desired idle speed for all engine operating conditions and loads.
^ The minimum idle air rate is set at the factory with a stop screw. This setting allows enough air
flow by the throttle valves to cause the IAC valve pintle to be positioned a calibrated number of
steps (counts), from the seat, during controlled idle operation.
^ If the IAC valve is disconnected and reconnected with the engine running, the idle speed may be
wrong. If this occurs, reset the IAC valve by depressing the accelerator pedal slightly, start and run
engine for five seconds, then turn ignition "OFF" for ten seconds.
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Idle Air Control (IAC): Adjustments
To reset Idle Air Control (IAC) valve.
1. Depress accelerator pedal slightly. 2. Start and run engine for 5 seconds. 3. Turn ignition "OFF"
for 10 seconds. 4. Restart engine and check for proper idle operation.
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Procedure
Idle Air Control (IAC): Service and Repair Idle Air Control (IAC) Reset Procedure
1. Depress the accelerator pedal slightly. 2. Start and run the engine for five seconds. 3. Turn the
ignition "OFF" for ten seconds. 4. Restart the engine and check for proper idle operation.
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Procedure > Page 3876
Idle Air Control (IAC): Service and Repair Idle Air Control (IAC) Valve Replacement
Throttle Body Exploded View
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Idle Air Control (IAC) <-->
[Idle Speed/Throttle Actuator - Electronic] > Component Information > Service and Repair > Idle Air Control (IAC) Reset
Procedure > Page 3877
IAC Valve
REMOVE OR DISCONNECT
1. Resonator. 2. Distributor ventilation vacuum line at air intake duct. 3. Electrical connector from
Intake Air Temperature (IAT) sensor. 4. Air intake duct. 5. Electrical connector from Idle Air Control
(IAC) valve. 6. IAC valve assembly attaching screws. 7. IAC valve assembly.
CLEAN AND INSPECT
^ Clean IAC valve O-ring sealing surface, pintle valve seat and air passage. The IAC valve may be cleaned using GM cleaner 1052626 or GM X-66A. Use a shop towel or parts
brush to remove heavy deposits.
- Shiny spots on the pintle or seat are normal, and do not indicate misalignment or a bent pintle
shaft. If air passage has heavy deposits, remove throttle body for complete cleaning.
^ Inspect IAC valve O-ring for cuts, cracks, or distortion. Replace if damaged.
NOTICE: If installing a new IAC valve, be sure to replace with an identical part. IAC valve pintle
shape and diameter are designed for specific application.
MEASURE (IF INSTALLING A NEW IAC)
^ Distance between tip of IAC valve pintle and mounting surface. If greater than 28 mm (1.100 in), use finger pressure to slowly retract the pintle. The force required
to retract the pintle of a NEW valve will not cause damage to the valve.
INSTALL OR CONNECT
1. Lubricate IAC valve O-ring with clean engine oil. 2. IAC Valve assembly. 3. IAC valve attaching
screws.
Tighten ^
IAC attaching screws to 3 Nm (27 lb in.).
4. Electrical connector to IAC valve. 5. Air intake duct. 6. Electrical connector to IAT valve. 7.
Distributor ventilation vacuum line at air intake duct. 8. Resonator. 9. Reset IAC valve pintle
position.
A. Depress accelerator slightly. B. Start engine and release accelerator pedal, run engine for 5
seconds. C. Turn engine "OFF" for 10 seconds. D. Restart engine and check for proper idle
operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Idle Air Control (IAC) <-->
[Idle Speed/Throttle Actuator - Electronic] > Component Information > Service and Repair > Idle Air Control (IAC) Reset
Procedure > Page 3878
Idle Air Control (IAC): Service and Repair Idle Air Control/Coolant Cover Assembly
Throttle Body Exploded View
REMOVE OR DISCONNECT
2. Negative battery cable. 2. Throttle body from intake manifold.
^ Refer to Throttle Body / Service and Repair.
DISASSEMBLE
1. Idle Air Control (IAC) valve. 2. IAC valve/coolant cover assembly screws. 3. IAC valve/coolant
cover assembly and gasket.
^ Discard gasket
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Idle Air Control (IAC) <-->
[Idle Speed/Throttle Actuator - Electronic] > Component Information > Service and Repair > Idle Air Control (IAC) Reset
Procedure > Page 3879
CLEAN AND INSPECT 1. Clean gasket sealing surface. 2. Inspect gasket sealing surface for
corrosion or damage that would cause a coolant leak. Replace cover assembly or throttle body if
necessary.
ASSEMBLE 1. Install new gasket and cover assembly. 2. IAC Valve / coolant cover assembly
screws.
Tighten ^
IAC Valve / coolant cover assembly screws to 3.2 Nm (28 lb in.).
3. If installing a new IAC valve, measure distance between pintle and mounting surface. If greater
than 28mm, use finger pressure to slowly retract
the pintle.
INSTALL OR CONNECT
1. Install and tighten IAC valve attaching screws
Tighten ^
IAC Valve assembly screws to 3 Nm (27 lb in.).
2. Install throttle body to intake manifold. 3. Negative battery cable. 4. Reset IAC valve pintle
position. Refer to ADJUSTMENTS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Serial Data <--> [Information
Bus] > Component Information > Description and Operation
Serial Data: Description and Operation
The Data Stream (on the 800 CKT) uses a 8192 Baud Rate During normal vehicle operation the
Powertrain Control Module (PCM) serves as the "Master" Module. When using the Tech-1 the
Tech-1, will serve as the "Master" Module and interrogate any Module on the 800 CKT.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Serial Data <--> [Information
Bus] > Component Information > Testing and Inspection > Circuit Operation
Serial Data: Testing and Inspection Circuit Operation
The Data Stream (on the 800 CKT) uses a 8192 Baud Rate During normal vehicle operation the
Powertrain Control Module (PCM) serves as the "Master" Module. When using the Tech-1 the
Tech-1, will serve as the "Master" Module and interrogate any Module on the 800 CKT.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Serial Data <--> [Information
Bus] > Component Information > Testing and Inspection > Circuit Operation > Page 3885
Serial Data: Testing and Inspection System Diagnostic Charts
Serial Data Line Diagnosis (800 CKT) (Part 1 Of 2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Serial Data <--> [Information
Bus] > Component Information > Testing and Inspection > Circuit Operation > Page 3886
Serial Data Line Diagnosis (800 CKT) (Part 2 Of 2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Serial Data <--> [Information
Bus] > Component Information > Testing and Inspection > Circuit Operation > Page 3887
Serial Data Line Diagnosis (800 CKT) (Part 1 Of 2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Serial Data <--> [Information
Bus] > Component Information > Testing and Inspection > Circuit Operation > Page 3888
Serial Data Line Diagnosis (800 CKT) (Part 2 Of 2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Specifications
Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Locations > Component Locations
Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Locations > Component Locations > Page 3894
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Diagrams > Diagram Information and Instructions
Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Information > Diagrams > Diagram Information and Instructions > Page 3897
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Information > Diagrams > Diagram Information and Instructions > Page 3898
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 3899
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 3900
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 3901
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 3902
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 3903
Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 3904
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 3905
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Information > Diagrams > Diagram Information and Instructions > Page 3906
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Information > Diagrams > Diagram Information and Instructions > Page 3924
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information > Diagrams > Diagram Information and Instructions > Page 3927
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Knock Sensor > Component
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Knock Sensor Circuit
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Information > Diagrams > Page 3929
Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
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Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
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Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
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Component Information > Locations
PCM With Knock Sensor Module
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Component Information > Locations > Page 3935
Knock Sensor Module: Service and Repair
PCM With Knock Sensor Module
Removing Knock Sensor Module From PCM
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Powertrain Control Module (PCM) from mounting bracket (refer to
PCM removal). 3. Knock sensor (KS) module access cover. 4. Knock sensor module.
INSTALL OR CONNECT
NOTICE: To prevent possible electrostatic discharge damage to the PCM and KS module, Do Not
touch the connector pins or soldered components on the circuit board.
1. Knock senor module. 2. Access cover. 3. PCM to mounting bracket (refer to PCM installation). 4.
Negative battery cable.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions
Malfunction Indicator Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Component Information > Diagrams > Diagram Information and Instructions > Page 3942
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Malfunction Indicator Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Component Information > Diagrams > Diagram Information and Instructions > Page 3969
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Manifold Pressure/Vacuum
Sensor > Component Information > Specifications > Electrical Specifications
MAP Sensor Chart
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Sensor > Component Information > Specifications > Electrical Specifications > Page 3975
Manifold Pressure/Vacuum Sensor: Mechanical Specifications
Manifold Absolute Pressure (MAP) Bolt
...................................................................................................................................................... 6
Nm (50 lb in.)
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Sensor > Component Information > Specifications > Page 3976
Manifold Pressure/Vacuum Sensor: Locations
MAP Sensor Location
Component Location - Pictorial View
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Sensor > Component Information > Diagrams > Diagram Information and Instructions
Manifold Pressure/Vacuum Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3979
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3980
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3981
Fig.1-Symbols (Part 1 Of 3)
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3982
Fig.2-Symbols (Part 2 Of 3)
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3983
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3984
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3985
Manifold Pressure/Vacuum Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3986
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3988
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3989
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3990
1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3991
Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 3992
FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Manifold Pressure/Vacuum
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 4009
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Manifold Pressure/Vacuum
Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 4010
Map Sensor Circuit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Manifold Pressure/Vacuum
Sensor > Component Information > Diagrams > Page 4011
Manifold Pressure/Vacuum Sensor: Description and Operation
MAP Sensor
The Manifold Absolute Pressure (MAP) sensor is a pressure sensor that measures changes in
intake manifold pressure. The pressure changes as a result of engine load and speed. The MAP
sensor converts this to a voltage output.
A closed throttle on engine coastdown would produce a relatively low MAP output while a
wide-open throttle would produce a high MAP output voltage. This high output voltage is produced
because the pressure inside the manifold is the same as outside the manifold, so you measure
100% of outside air pressure. Manifold Absolute Pressure (MAP) is inversely proportional to what
you would measure on a vacuum gage. When manifold pressure is high vacuum is low. The MAP
sensor is also used to measure barometric pressure under certain conditions which allows the
Powertrain Control Module (PCM) to automatically adjust for different altitudes.
The PCM sends a 5 volt reference signal to the MAP sensor. As the manifold pressure changes the
electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage the
PCM knows the manifold pressure. The PCM uses the MAP sensor to control ignition timing. The
MAP sensor is also used for speed density fuel management. When the PCM detects a
malfunction with the Mass Air Flow (MAF) sensor circuit the PCM will default to speed density.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Manifold Pressure/Vacuum
Sensor > Component Information > Diagrams > Page 4012
Manifold Pressure/Vacuum Sensor: Service and Repair
MAP Sensor Location
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Resonator. 3. Electrical connector. 4. Hold down bolts (2). 5. Sensor
from intake manifold.
INSTALL OR CONNECT
1. New sensor seal (lightly coated with clean engine oil). 2. Sensor into intake manifold. 3. Hold
down bolts. 4. Torque to 6 Nm (50 lb in). 5. Connect electrical connector. 6. Resonator. 7. Connect
negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Memory Calibration Unit >
Component Information > Technical Service Bulletins > PROM/MEMCAL - Identification Marks
Memory Calibration Unit: Technical Service Bulletins PROM/MEMCAL - Identification Marks
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 44-65-01
Date: October, 1994
Subject: New PROM/MEMCAL Identification Markings
Models: 1995 and Prior Passenger Cars and Trucks
Note:
For the purposes of this document, the terms PROM and MEMCAL will be used interchangeably.
To simplify identification of service PROMs. a new external marking format will be implemented.
Parts manufactured after Sept. 1994 will feature these new markings. This change will place the full
8-digit service part number on the PROM, in place of the old 4-digit "EXTERNAL ID" number. In the
past, parts and service personnel could not identify a PROM without using a cross-reference table
that matched external IDs and service numbers. In the future, the cross-reference table will not be
required for PROMs; parts will be ordered directly from the number appearing on the PROM.
However, the label will retain the broadcast code alpha characters to allow continued use of
cross-reference charts, if so desired.
Old Marking Format:
New Marking Format:
^ Ordering the above PROM from the old marking format would require using a cross-reference
chart to determine a service part number, based on the BROAD CAST CODE and EXTERNAL ID
NUMBERS.
^ To order from the new format, simply combine the 2nd and 3rd lines to form an 8-digit part
number that can be directly ordered from SPO (number 16134624 in the above example).
As these changes are phased into the parts inventory, it should be noted that dealers will continue
to see parts with both formats for some time in the future. This is because:
^ Millions of vehicles have already been built with the old format.
^ SPO has existing stock of MEMCALs and PROMs with the old format.
^ PROMS with 7-digit part numbers (representing less than 10% of current part numbers) will
continue to use the old format. The 7-digit part numbers are easily identified because they always
begin with "122xxxx".
Due to manufacturing processes, more than one 8-digit part number may appear on a MEMCAL. In
this event, service personnel should use the label on the exterior cover of the MEMCAL assembly.
To avoid confusion, only the service label will include the BROAD CAST CODE, consisting of letter
characters (I.E., ARCL).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Memory Calibration Unit >
Component Information > Technical Service Bulletins > PROM/MEMCAL - Identification Marks > Page 4017
CHANGES TO MEMCAL/PROM LABELING FORMATS
^ MEMCALs may use either INK-JET or ADHESIVE labels, as shown.
^ PROMs will always use ADHESIVE labels with the same format as shown for MEMCALs. These
changes will become effective on parts manufactured after 10/94.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Quad Driver <--> [Output
Driver] > Component Information > Locations
Quad Driver: Locations
Quad/Output drivers are hard wired onto the ECM/PCM/VCM.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Quad Driver <--> [Output
Driver] > Component Information > Locations > Page 4021
Quad Driver: Description and Operation
Quad/Output Driver Module
The Control Module in this vehicle controls most components with electronic switches which
complete a ground circuit when turned on.
When the switches are arranged in groups of 4, they can independently control up to 4 outputs and
are called Quad Drivers.
When the switches are arranged in groups of 7, they can independently control up to 7 outputs and
are called Output Drivers.
Not all outputs are always used.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Quad Driver <--> [Output
Driver] > Component Information > Locations > Page 4022
Quad Driver: Testing and Inspection
Little or no quad driver testing was supplied by the manufacturer. The engine module decides when
to turn each switch of the driver "ON".
Even though some models will set codes, in the end, if you want to check the driver itself, you'll
need:
1. To use a scantool to command the suspected driver switch to energize (ground) the circuit, while
checking with a test light, 2. To operate the vehicle in a way that should cause the suspected
portion of the driver to switch "ON".
On the up side, since the early 90's, most driver load circuits utilized circuit breakers. This
protected most drivers and engine models from burning up when the circuit was overloaded.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Quad Driver <--> [Output
Driver] > Component Information > Locations > Page 4023
Quad Driver: Service and Repair
Quad/Output drivers are hard wired onto the ECM/PCM/VCM, and can't be serviced separately.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Technical Service Bulletins > Oxygen Sensors - Silica Contamination
Oxygen Sensor: Technical Service Bulletins Oxygen Sensors - Silica Contamination
Model Year: 1981
Bulletin No: 81-I-37
File In Group: 60
Number: 11
Date: Feb. 81
Subject: Silica Contamination of Oxygen Sensors and Gelation of Oil.
Models Affected: All
Oxygen sensor performance can deteriorate if certain RTV silicone gasket materials are used.
Other RTV's when used with certain oils, may cause gelation of the oil. The degree of performance
severity depends on the type of RTV and application of the engine involved.
Therefore, when repairing engines where this item is involved, it is important to use either cork
composition gaskets or RTV silicone gasket material approved for such use. GMS (General Motors
Sealant) or equivalent material can be used. GMS is available through GMPD with the following
part numbers:
1052366 3 oz.
1052434 10.14 oz.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Specifications > Electrical Specifications
Oxygen Sensor Output
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Specifications > Electrical Specifications > Page 4030
Oxygen Sensor: Mechanical Specifications
Heated Oxygen Sensor (HO2S) ..........................................................................................................
......................................................... 41 Nm (30 lb ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Locations > LH
Engine, Left Side Lower
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Locations > LH > Page 4033
Lower Right Side Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Locations > LH > Page 4034
HO2S Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions
Oxygen Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4037
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4038
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4039
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4040
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4041
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4042
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4043
Oxygen Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4044
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4045
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Oxygen Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4046
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Component Information > Diagrams > Diagram Information and Instructions > Page 4068
Oxygen Sensor: Electrical Diagrams
Heated Oxygen Sensor (HO2S) Sensor Circuit.
Right Heated Oxygen Sensor Circuit.
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Oxygen Sensor: Description and Operation
HO2S Cutaway
Oxygen Sensor Element
The Heated Oxygen Sensor (HO2S) is essentially a small variable battery; it has the ability to
produce a low voltage signal that feeds information on engine exhaust oxygen content to the
Powertrain Control Module (PCM).
The PCM sends a reference signal of 450 mV. The reference signal serves to run the engine when
it is in "Open Loop" mode of operation. When the air/fuel ratio is correct the PCM displays 450 mV.
When the engine is operating with a rich air/fuel ratio, there is a reduction of free oxygen in the
exhaust stream and the oxygen voltage rises above the reference voltage.
The HO2S is constructed from a material (zirconia/platinum) that conducts electricity under certain
conditions. At operating temperature, 315°C (60o° F), the element becomes a semiconductor. A
platinum coating on the outer surface of the element stimulates further combustion of the exhaust
gases right
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at the surface and this helps keep the element up to the desired temperature. The HO2S has an
inter cavity which is filled with atmospheric (reference) air. The reference air has approximately
21% oxygen in it. In this electrical circuit this inter cavity is the positive (+) terminal. The outer
surface of the element is exposed to the exhaust gas stream. It is the negative (-) or ground
terminal. The oxygen concentration differences between the reference air and exhaust gases
produce small voltages.
A rich exhaust (excessive fuel) has almost no oxygen. When there is a large difference in the
amount of oxygen touching the inside and outside surfaces, there is more conduction, and the
sensor puts out a voltage signal above 600 mV. With lean exhaust (excessive oxygen) there is
about two percent oxygen in the exhaust. This is a smaller difference in oxygen from the outside
surfaces which results in less conduction and a voltage signal below 300 mV. The voltages are
monitored and used by the PCM to "fine tune" the air/fuel ratio to achieve the ideal mixture desired.
When the engine is running lean. the voltage drops below the reference voltage due to excess
oxygen in the exhaust stream. The HO2S provides the feedback information for the "Closed Loop"
operating mode of the fuel delivery system. The HO2S indicates to the PCM what is happening in
the exhaust. It does not cause things to happen. It is a type of gage: Low voltage output = lean
mixture = high oxygen content in exhaust; high voltage output = rich mixture = low oxygen content
in the exhaust.
An open Heated Oxygen Sensor (HO2S) circuit, should set Diagnostic Trouble Code (DTC) 13 or
63. A constant low voltage in the HO2S circuit could set a DTC 44 or 64. A constant high voltage in
the circuit should set a DTC 45 or 65. DTCs 44. 45. 64, or 65 could also be set as a result of fuel
system problems.
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Oxygen Sensor: Service and Repair
HO2S Location
CAUTION: The Heated Oxygen Sensor (HO2S) uses a permanently attached pigtail and
connector. This pigtail should not be removed from the oxygen sensor. Damage or removal of the
pigtail or connector could affect proper operation of the oxygen sensor.
^ Take care when handling the oxygen sensor. The in-line electrical connector and louvered end
must be kept free off grease, dirt or other contaminants. Also, avoid using cleaning solvents of any
type. Be careful not to subject the sensor to sharp impact.
REMOVAL:
NOTICE: The HO2S may be difficult to remove when engine temperature is below 48° C (120° F).
Excessive force may damage threads in exhaust pipe.
1. Disconnect the negative battery cable. 2. Raise vehicle. 3. Disconnect the oxygen sensor
electrical connector. 4. Carefully remove the oxygen sensor.
INSTALLATION:
NOTICE: A special anti-seize compound is used on the oxygen sensor threads. The compound
consists of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will
remain, making the sensor easier to remove. New or service sensors will already have the
compound applied to the threads. If a sensor is removed from an engine, and, if for any reason it is
to be reinstalled, the threads must have anti-seize compound applied before reinstallation.
1. Coat the threads of the HO2S with anti-seize compound P/N 5613695, or equivalent if
necessary. 2. Install the sensor in the engine, and tighten to 41 Nm (30 ft lb). 3. Connect the
electrical connector. 4. Lower vehicle. 5. Connect the negative battery cable.
NOTICE: The system has a learning ability which allows it to make corrections for minor variations
in the fuel system to improve driveability. When the battery is disconnected the computer's memory
is cleared and the learning process has to begin all over again. A change may be noticed in the
driving performance of the vehicle. To reset the vehicles learning ability, make sure the engine is at
operating temperature and operate the vehicle at part throttle, moderate acceleration, and idle
conditions, until normal performance returns.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Power Steering Pressure
Switch > Component Information > Locations
Left Front Of Engine
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Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 4082
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Power Steering Pressure Switch Circuit.
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Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Relays and Modules Computers and Control Systems > Engine Control Module > Component Information > Technical Service Bulletins > Engine
Controls - Aftermarket Accessory Usage
Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory
Usage
INFORMATION
Bulletin No.: 04-06-04-054B
Date: November 18, 2010
Subject: Info - Non-GM Parts and Accessories (Aftermarket)
Models:
2011 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed
Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate
Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System).
The recent rise and expansion of companies selling non-GM parts and accessories has made it
necessary to issue this reminder to dealers regarding GM's policy on the use and installation of
these aftermarket components.
When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to
use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs,
special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the
same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty
repairs, special policy repairs or any repairs paid for by GM.
During a warranty repair, if a GM original equipment part is not available through GM Customer
Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources,
the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order
the circumstances surrounding why non-GM parts were used. The dealer must give customers
written notice, prior to the sale or service, that such parts or accessories are not marketed or
warranted by General Motors.
It should also be noted that dealers modifying new vehicles and installing equipment, parts and
accessories obtained from sources not authorized by GM are responsible for complying with the
National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed
by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design
characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully
understand that non-GM approved parts may not have been validated, tested or certified for use.
This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part
failure occurs as the result of the installation or use of a non-GM approved part, the warranty will
not be honored.
A good example of non-authorized modification of vehicles is the result of an ever increasing
supply of aftermarket devices available to the customer, which claim to increase the horsepower
and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to
one or more of the following modifications:
- Propane injection
- Nitrous oxide injection
- Additional modules (black boxes) that connect to the vehicle wiring systems
- Revised engine calibrations downloaded for the engine control module
- Calibration modules which connect to the vehicle diagnostic connector
- Modification to the engine turbocharger waste gate
Although the installation of these devices, or modification of vehicle components, can increase
engine horsepower and torque, they may also negatively affect the engine emissions, reliability
and/or durability. In addition, other powertrain components, such as transmissions, universal joints,
drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the
installation of these devices.
General Motors does not support or endorse the use of devices or modifications that, when
installed, increase the engine horsepower and torque. It is because of these unknown stresses,
and the potential to alter reliability, durability and emissions performance, that GM has adopted a
policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining
warranty coverage, to the powertrain and driveline components whenever the presence of a
non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is
subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or
06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for
calibration verification.
These same policies apply as they relate to the use of non-GM accessories. Damage or failure
from the use or installation of a non-GM accessory will not be covered under warranty. Failure
resulting from the alteration or modification of the vehicle, including the cutting, welding or
disconnecting of the vehicle's original equipment parts and components will void the warranty.
Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal
inquiry at either the local, state or federal level that
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results from the alteration or modification of a vehicle using non-GM approved parts or accessories.
Dealers should be especially cautious of accessory companies that claim the installation of their
product will not void the factory warranty. Many times these companies have even given direction
on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from
finding out that is has been installed.
Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada
by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair
is to be made on the vehicle, even with the installation of such non-GM approved components, the
customer is to be made aware of General Motors position on this issue and is to sign the
appropriate goodwill documentation required by General Motors.
It is imperative for dealers to understand that by installing such devices, they are jeopardizing not
only the warranty coverage, but also the performance and reliability of the customer's vehicle.
Disclaimer
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Engine Control Module: Technical Service Bulletins PROM - Reprogram Using Off Board Program
Adapter
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 73-65-13
Date: March, 1997
INFORMATION
Subject: Reprogramming Capability using the Off Board Programming Adapter
Models: 1993-97 Passenger Cars and Trucks (Applicable Reprogrammable Vehicles)
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The General Motors vehicles contain Electronically Reprogrammable Devices (i.e. PCM, VCM,
ECM). These vehicles cannot be programmed through PROM replacement, however service
programming capability is available through the Tech 1/1A, Tech 2 and Techline terminals via
direct or remote programming.
The Environmental Protection Agency (EPA) has requested that all new vehicle manufacturers
ensure their dealers/retailers are aware that they are responsible for providing customers access to
reprogramming services at a reasonable cost and in a timely manner.
Although programming of controllers has become a common service practice at GM
dealers/retailers, the EPA has received reports from consumers and the aftermarket repair industry
that they were unable to purchase a new (programmed) Electronically Reprogrammable Device
(ERD) over-the-counter. As a result, on August 1, 1995, the Federal Government issued a
regulation requiring all manufacturers to make available reprogramming to the independent
aftermarket by December 1, 1997.
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Controls - Aftermarket Accessory Usage > Page 4119
Today, the Off Board Programming Adapter (OBPA) is used to reprogram ERD's sold
over-the-counter. For all practical purposes, the OBPA takes the place of the vehicle when the
vehicle is not available.
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Controls - Aftermarket Accessory Usage > Page 4122
The list of dealerships/retailers currently own the OBPA (see Attachments 1 - 3). These locations
are equipped to provide over-the-counter preprogrammed ERD's. The hardware required to
perform reprogramming in addition to the OBPA is a Techline terminal, Tech 1/1A and associated
cables and adapters. THE TECH 2 SHOULD NOT BE USED WITH THE OBPA AT THIS TIME
BECAUSE OF INADEQUATE OBPA GROUNDING.
The current OBPA can support reprogramming on all late model General Motor's vehicles except:
^ Premium V-8's
^ 1996 Diesel Truck
^ Cadillac Catera
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^ All 1997 programmable vehicles (requires use of the Tech 2)
A modification to the OBPA is being offered by Kent-Moore to support these additional vehicles and
to allow reprogramming using the Tech 2. The revisions to the OBPA for the Tech 2 is very
important as the Tech 2 is the only tool used for service programming for 1997 and future vehicles.
To have the modifications performed, contact Kent-Moore at (800) 345-2233. The revisions (part
number J 41207 REV-C) are free of charge for GM dealerships/retailers.
A dealership/retailer can purchase the OBPA by contacting Kent-Moore (part number J 41207-C).
Support on how to use the OBPA is provided by the Techline Customer Support Center (TCSC) at
(800) 828-6860 (English) or (800) 503-3222 (French).
If you need to purchase an OBPA and/or cable, contact Kent-Moore at (800) 345-2233. The OBPA
retails for $695.00 (includes all revisions 1-4) under part number J 41207-C.
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4124
Engine Control Module: Specifications
Powertrain Control Module (PCM)
..............................................................................................................................................................
3 Nm (26 lb in.)
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PCM Location
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Page 4127
Engine Control Module: Connector Locations
Powertrain Control Module (PCM)
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Page 4128
Powertrain Control Module (PCM)
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Page 4129
Powertrain Control Module (PCM)
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Page 4130
Powertrain Control Module (PCM)
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and Instructions
Engine Control Module: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Engine Control Module: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Engine Control Module: Connector Views
Powertrain Control Module (PCM): A
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Powertrain Control Module (PCM): B
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Powertrain Control Module (PCM): C
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Powertrain Control Module (PCM): D
Pinout Information
PCM Connectors
CAUTION: Do not backprobe Powertrain Control Module (PCM) connectors! The connectors are
sealed for operation in an underhood environment. Backprobing may damage the seal which could
eventually cause the connector to fail due to corrosion.
This information applies to the PCM connector charts in the next four images. These charts may be
used with the J 39700-A breakout box in conjunction with J 39700-110 and J 39700-140 cables
and high impedance digital multimeter J 39200 to obtain voltage present for each circuit listed.
Install the
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breakout box between the PCM connectors and the PCM. The breakout box PIN numbers
correspond with the PCM connector PIN numbers. Voltage may vary slightly, but should be very
close. Certain exceptions are called out in the chart legend below.
The following conditions must be met before checking typical voltages:
Key "ON":
^ DVM negative (black) lead connected to a known good ground.
^ Scan tool "NOT" installed.
^ All accessories "OFF."
^ Battery fully charged.
Engine Running:
^ All conditions listed above.
^ Engine at normal operating temperature.
^ Engine at idle/closed throttle/operating in "Closed Loop."
^ In park or neutral.
CHART LEGEND
(1) Less than .5 volt when system enabled. (2) Battery voltage for first two seconds with ignition
"ON." (3) Varies. (4) Varies with temperature. (5) Battery voltage when in gear. (6) Less than .5 volt
with brake pedal applied. (7) Battery voltage with A/C "ON." (8) Varies with altitude. (9) Less than
.5 volt with high power steering load. (*) Less than .5 volt.
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Connector "A"
RED
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Connector "B"
BLACK
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Connector "C"
GREY/CLEAR
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Connector "D"
BLUE
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Engine Control Module: Description and Operation
PCM Connectors
The Powertrain Control Module (PCM) is the control center of the fuel injection system. It
constantly looks at the information from various sensors and controls the systems that affect
vehicle performance. The PCM also performs a diagnostic function check of the system. It can
recognize operational problems and alert the driver through the Malfunction Indicator Lamp (MIL)
"Service Engine Soon" and store Diagnostic Trouble Code(s) (DTC) which identify the problem
areas to aid the technicians making repairs.
The PCM supplies 5 or 12 volts to power various sensors or switches. This is done through
resistances in the PCM which are so high in value that a test light will not light when connected to
the circuit. In some cases, even an ordinary shop voltmeter will not give an accurate reading
because its resistance is too low. Therefore, the use of a 10 megohm input impedance digital
voltmeter (J 39200) is required to assure accurate voltage readings.
Refer to Computers and Controls / System Diagnosis / Flow of Diagnosis / "Strategy Based
Diagnostics" for more information on using the diagnostic function of the PCM.
MEMORY
There are three types of memory storage within the PCM: Read Only Memory (ROM), Random
Access Memory (RAM) and Electrically Erasable Programmable Read Only Memory (EEPROM).
ROM Read Only Memory (ROM) is a permanent memory that is physically soldered to the circuit
boards within the PCM. The ROM contains the overall control programs. Once the ROM is
programmed, it cannot be changed. The ROM memory is non-erasable, and does not need power
to be retained.
RAM Random Access Memory (RAM) is the microprocessor "scratch pad." The processor can
write into, or read from this memory as needed. This memory is erasable and needs a constant
supply of voltage to be retained. If the voltage is lost, the memory is lost.
EEPROM Electrically Erasable Programmable Read Only Memory (EEPROM) is a permanent
memory that is physically soldered to the circuit boards within the PCM. The EEPROM contains the
overall control algorithms. The EEPROM can be reprogrammed by using the Tech 1 scan tool or
other Decline terminal/equipment.
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Tests and General Diagnostics
Engine Control Module: Component Tests and General Diagnostics
To display diagnostic trouble codes, use a Tech 1 (or equivalent scanner). Grounding the DLC will
NOT flash Diagnostic Trouble Code(s) (DTC), but will enable most outputs when the ignition is
"ON" engine "OFF." Grounding the Data Link Connector (DLC) while the engine is running will
cause the Malfunction Indicator Lamp (MIL) to flash to indicate "Open" or "Closed Loop. This is
referred to as Field Service Mode."
To clear the DTCs from memory use the Tech 1 or:
^ ignition "OFF."
^ Disconnect the # 2 fuse (located in the underhood electrical center) for 30 seconds.
Since the Powertrain Control Module (PCM) can have a failure which may affect only one circuit,
following the diagnostic procedures in this section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections or PCM is the cause of a problem and the
PCM is replaced the Knock Sensor (KS) module must be transferred to the new PCM and the new
PCM must then be programmed. If this does not correct the problem, one of the following may be
the reason:
^ There is a problem with the PCM terminal connections. The diagnostic chart will say PCM
connections or PCM. The terminals may have to be removed from the connector in order to check
them properly.
^ The problem is intermittent. This means that the problem is not present at the time the system is
being checked. In this case. Refer to Diagnosis by Symptom and make a careful physical
inspection of all portions of the system involved.
^ Shorted solenoid, relay coil, or harness. Solenoids and relays are turned "ON" and "OFF" by the
PCM using internal electronic switches called
"drivers."
A shorted solenoid, relay coil, or PCM harness will not damage the PCM but will cause the
component to be inoperative.
J 34636 or BT-8405 testers or equivalent provide a fast accurate means of checking for a shorted
coil or a short to battery voltage.
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Engine Control Module: Service and Repair
Removal
Hardware Removal
NOTE: To prevent internal Powertrain Control Module (PCM) damage, the ignition must be "OFF",
when disconnecting or reconnecting power to the PCM.
Remove or Disconnect:
1. Disconnect negative battery cable 2. Disconnect PCM mounting hardware 3. Disconnect PCM
electrical connectors 4. Remove PCM from engine compartment
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PCM With Knock Sensor Module
5. Remove PCM access cover
Removing Knock Sensor Module From PCM
6. Remove knock sensor module from PCM
Install or Connect:
1. Install knock sensor module and access cover 2. Install PCM in vehicle 3. Connect PCM
electrical connectors 4. Connect PCM mounting hardware 5. Connect negative battery cable
EEPROM Programming
CAUTION:The software/calibration used for PCM reprogramming must match the vehicle
application, or improper operation and/or damage may
occur.
^ Ensure battery is charged
^ Turn ignition "ON"
^ Ensure connections to the Data Link Connector (DLC) and battery/cigar lighter are secure
^ Follow the most current Decline terminal/equipment instructions
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PCM Reprogramming Failure
^ Check PCM connections
^ Check Decline terminal/equipment for latest software version
^ Repeat reprogramming procedures. If it fails again, replace the PCM. The replacement PCM
must be programmed.
PCM Functional Check
^ Refer to System Diagnosis / Diagnostic System Check.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Relays and Modules Computers and Control Systems > Knock Sensor Module > Component Information > Locations
PCM With Knock Sensor Module
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Knock Sensor Module: Service and Repair
PCM With Knock Sensor Module
Removing Knock Sensor Module From PCM
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Powertrain Control Module (PCM) from mounting bracket (refer to
PCM removal). 3. Knock sensor (KS) module access cover. 4. Knock sensor module.
INSTALL OR CONNECT
NOTICE: To prevent possible electrostatic discharge damage to the PCM and KS module, Do Not
touch the connector pins or soldered components on the circuit board.
1. Knock senor module. 2. Access cover. 3. PCM to mounting bracket (refer to PCM installation). 4.
Negative battery cable.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Locations > Component Locations
Powertrain Control Module (PCM)
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Page 4188
Powertrain Control Module (PCM)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Instructions > Page 4191
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Instructions > Page 4193
Fig.1-Symbols (Part 1 Of 3)
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Instructions > Page 4194
Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Instructions > Page 4197
Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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Instructions > Page 4204
FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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MAF Sensor Circuit.
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Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
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and Instructions
Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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and Instructions > Page 4257
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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and Instructions > Page 4259
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Coolant Temperature Sensor/Switch (For Computer) > Component Information >
Specifications
Coolant Temperature Sensor/Switch (For Computer): Specifications
Engine Coolant Temperature (ECT) Sensor
................................................................................................................................................ 23 Nm
(17 lb ft.)
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Coolant Temperature Sensor/Switch (For Computer): Locations
Left Front Of Engine
The engine coolant temperature sensor is located near water pump.
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Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value
based on temperature) immersed in the engine coolant stream. Low coolant temperature produces
a high resistance while high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the ECT through a resistor in the
PCM and measures the voltage. The voltage will be high when the engine is cold and low when the
engine is hot. By measuring the voltage. the PCM knows the engine coolant temperature. Engine
coolant temperature affects most systems the PCM controls. A failure in the ECT circuit should set
either a Diagnostic Trouble Code (DTC) 14 or 15. Remember these DTCs indicate a failure in the
engine coolant temperature sensor circuit, so proper use of the chart will lead to either repairing a
wiring problem or replacing the sensor to properly repair a problem.
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Specifications > Page 4265
Coolant Temperature Sensor/Switch (For Computer): Service and Repair
Engine Coolant Temperature Sensor
IMPORTANT: Care must be taken when handling engine coolant (ECT) temperature sensor.
Damage to engine coolant sensor will affect proper operation of the fuel injection system.
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Relieve coolant pressure. 3. Electrical connector. 4. Carefully back out
sensor.
INSTALL OR CONNECT
1. Coat threads with sealer. 2. Install sensor in engine. 3. Torque to 23 Nm (17 ft lb). 4. Connect
electrical connector. 5. Refill lost coolant. 6. Connect negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Crankshaft Position Sensor > Component Information > Diagrams > Diagram
Information and Instructions
Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Information and Instructions > Page 4270
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information and Instructions > Page 4272
Fig.1-Symbols (Part 1 Of 3)
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Information and Instructions > Page 4273
Fig.2-Symbols (Part 2 Of 3)
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Information and Instructions > Page 4274
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Information and Instructions > Page 4276
Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information and Instructions > Page 4298
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Intake Air Temperature Sensor > Component Information > Specifications
Intake Air Temperature Sensor: Specifications Torque Valve
Torque Valve
Induction Air Sensor 44 in.lb
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Intake Air Temperature Sensor: Locations IAT Sensor
The Intake Air Temperature (IAT) sensor is located in the air ducting, just forward of the throttle
body assembly.
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Intake Air Temperature Sensor: Locations Intake Air Temperature (IAT) Sensor
Component Location - Pictorial View
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Page 4307
Component Location - Pictorial View
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Information and Instructions
Intake Air Temperature Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information and Instructions > Page 4312
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Intake Air Temperature Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information and Instructions > Page 4338
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information and Instructions > Page 4340
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information and Instructions > Page 4341
Intake Air Temperature (IAT) Sensor Circuit.
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Intake Air Temperature Sensor: Description and Operation
Engine Coolant Temperature (ECT) Sensor
The Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on
temperature). It is mounted in the air intake duct. Low temperature produces a high resistance and
high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the sensor through a resistor in
the PCM and measures the voltage. The voltage will be high when the intake air is cold, and low
when the intake manifold air is hot. By measuring the voltage, the PCM knows the intake air
temperature. A failure in the IAT sensor circuit should set either a DTC 23 or DTC 25.
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Intake Air Temperature Sensor: Service and Repair
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Electrical connector. 3. Carefully remove sensor from air duct.
INSTALL OR CONNECT
1. Install sensor in engine. 2. Connect electrical connector. 3. Connect negative battery cable.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Knock Sensor > Component Information > Specifications
Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Knock Sensor > Component Information > Locations > Component Locations
Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
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4349
Engine Harness/U/Hood Electrical Center, Right Side
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Instructions
Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Instructions > Page 4354
Fig.1-Symbols (Part 1 Of 3)
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Instructions > Page 4355
Fig.2-Symbols (Part 2 Of 3)
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Instructions > Page 4356
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Instructions > Page 4358
Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor Circuit
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Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
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Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
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Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
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Electrical Specifications
MAP Sensor Chart
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Electrical Specifications > Page 4391
Manifold Pressure/Vacuum Sensor: Mechanical Specifications
Manifold Absolute Pressure (MAP) Bolt
...................................................................................................................................................... 6
Nm (50 lb in.)
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4392
Manifold Pressure/Vacuum Sensor: Locations
MAP Sensor Location
Component Location - Pictorial View
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Information and Instructions
Manifold Pressure/Vacuum Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Manifold Pressure/Vacuum Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Information and Instructions > Page 4421
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Information and Instructions > Page 4422
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information and Instructions > Page 4423
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Information and Instructions > Page 4424
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information and Instructions > Page 4425
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information and Instructions > Page 4426
Map Sensor Circuit.
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Manifold Pressure/Vacuum Sensor: Description and Operation
MAP Sensor
The Manifold Absolute Pressure (MAP) sensor is a pressure sensor that measures changes in
intake manifold pressure. The pressure changes as a result of engine load and speed. The MAP
sensor converts this to a voltage output.
A closed throttle on engine coastdown would produce a relatively low MAP output while a
wide-open throttle would produce a high MAP output voltage. This high output voltage is produced
because the pressure inside the manifold is the same as outside the manifold, so you measure
100% of outside air pressure. Manifold Absolute Pressure (MAP) is inversely proportional to what
you would measure on a vacuum gage. When manifold pressure is high vacuum is low. The MAP
sensor is also used to measure barometric pressure under certain conditions which allows the
Powertrain Control Module (PCM) to automatically adjust for different altitudes.
The PCM sends a 5 volt reference signal to the MAP sensor. As the manifold pressure changes the
electrical resistance of the MAP sensor also changes. By monitoring the sensor output voltage the
PCM knows the manifold pressure. The PCM uses the MAP sensor to control ignition timing. The
MAP sensor is also used for speed density fuel management. When the PCM detects a
malfunction with the Mass Air Flow (MAF) sensor circuit the PCM will default to speed density.
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Manifold Pressure/Vacuum Sensor: Service and Repair
MAP Sensor Location
REMOVE OR DISASSEMBLE
1. Negative battery cable. 2. Resonator. 3. Electrical connector. 4. Hold down bolts (2). 5. Sensor
from intake manifold.
INSTALL OR CONNECT
1. New sensor seal (lightly coated with clean engine oil). 2. Sensor into intake manifold. 3. Hold
down bolts. 4. Torque to 6 Nm (50 lb in). 5. Connect electrical connector. 6. Resonator. 7. Connect
negative battery cable.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Oxygen Sensor > Component Information > Technical Service Bulletins > Oxygen
Sensors - Silica Contamination
Oxygen Sensor: Technical Service Bulletins Oxygen Sensors - Silica Contamination
Model Year: 1981
Bulletin No: 81-I-37
File In Group: 60
Number: 11
Date: Feb. 81
Subject: Silica Contamination of Oxygen Sensors and Gelation of Oil.
Models Affected: All
Oxygen sensor performance can deteriorate if certain RTV silicone gasket materials are used.
Other RTV's when used with certain oils, may cause gelation of the oil. The degree of performance
severity depends on the type of RTV and application of the engine involved.
Therefore, when repairing engines where this item is involved, it is important to use either cork
composition gaskets or RTV silicone gasket material approved for such use. GMS (General Motors
Sealant) or equivalent material can be used. GMS is available through GMPD with the following
part numbers:
1052366 3 oz.
1052434 10.14 oz.
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Oxygen Sensor Output
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Page 4435
Oxygen Sensor: Mechanical Specifications
Heated Oxygen Sensor (HO2S) ..........................................................................................................
......................................................... 41 Nm (30 lb ft.)
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Oxygen Sensor > Component Information > Locations > LH
Engine, Left Side Lower
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Lower Right Side Of Engine
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HO2S Location
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Oxygen Sensor > Component Information > Diagrams > Diagram Information and
Instructions
Oxygen Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Instructions > Page 4442
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Instructions > Page 4444
Fig.1-Symbols (Part 1 Of 3)
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Instructions > Page 4445
Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Oxygen Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Oxygen Sensor: Electrical Diagrams
Heated Oxygen Sensor (HO2S) Sensor Circuit.
Right Heated Oxygen Sensor Circuit.
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Oxygen Sensor: Description and Operation
HO2S Cutaway
Oxygen Sensor Element
The Heated Oxygen Sensor (HO2S) is essentially a small variable battery; it has the ability to
produce a low voltage signal that feeds information on engine exhaust oxygen content to the
Powertrain Control Module (PCM).
The PCM sends a reference signal of 450 mV. The reference signal serves to run the engine when
it is in "Open Loop" mode of operation. When the air/fuel ratio is correct the PCM displays 450 mV.
When the engine is operating with a rich air/fuel ratio, there is a reduction of free oxygen in the
exhaust stream and the oxygen voltage rises above the reference voltage.
The HO2S is constructed from a material (zirconia/platinum) that conducts electricity under certain
conditions. At operating temperature, 315°C (60o° F), the element becomes a semiconductor. A
platinum coating on the outer surface of the element stimulates further combustion of the exhaust
gases right
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at the surface and this helps keep the element up to the desired temperature. The HO2S has an
inter cavity which is filled with atmospheric (reference) air. The reference air has approximately
21% oxygen in it. In this electrical circuit this inter cavity is the positive (+) terminal. The outer
surface of the element is exposed to the exhaust gas stream. It is the negative (-) or ground
terminal. The oxygen concentration differences between the reference air and exhaust gases
produce small voltages.
A rich exhaust (excessive fuel) has almost no oxygen. When there is a large difference in the
amount of oxygen touching the inside and outside surfaces, there is more conduction, and the
sensor puts out a voltage signal above 600 mV. With lean exhaust (excessive oxygen) there is
about two percent oxygen in the exhaust. This is a smaller difference in oxygen from the outside
surfaces which results in less conduction and a voltage signal below 300 mV. The voltages are
monitored and used by the PCM to "fine tune" the air/fuel ratio to achieve the ideal mixture desired.
When the engine is running lean. the voltage drops below the reference voltage due to excess
oxygen in the exhaust stream. The HO2S provides the feedback information for the "Closed Loop"
operating mode of the fuel delivery system. The HO2S indicates to the PCM what is happening in
the exhaust. It does not cause things to happen. It is a type of gage: Low voltage output = lean
mixture = high oxygen content in exhaust; high voltage output = rich mixture = low oxygen content
in the exhaust.
An open Heated Oxygen Sensor (HO2S) circuit, should set Diagnostic Trouble Code (DTC) 13 or
63. A constant low voltage in the HO2S circuit could set a DTC 44 or 64. A constant high voltage in
the circuit should set a DTC 45 or 65. DTCs 44. 45. 64, or 65 could also be set as a result of fuel
system problems.
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Oxygen Sensor: Service and Repair
HO2S Location
CAUTION: The Heated Oxygen Sensor (HO2S) uses a permanently attached pigtail and
connector. This pigtail should not be removed from the oxygen sensor. Damage or removal of the
pigtail or connector could affect proper operation of the oxygen sensor.
^ Take care when handling the oxygen sensor. The in-line electrical connector and louvered end
must be kept free off grease, dirt or other contaminants. Also, avoid using cleaning solvents of any
type. Be careful not to subject the sensor to sharp impact.
REMOVAL:
NOTICE: The HO2S may be difficult to remove when engine temperature is below 48° C (120° F).
Excessive force may damage threads in exhaust pipe.
1. Disconnect the negative battery cable. 2. Raise vehicle. 3. Disconnect the oxygen sensor
electrical connector. 4. Carefully remove the oxygen sensor.
INSTALLATION:
NOTICE: A special anti-seize compound is used on the oxygen sensor threads. The compound
consists of a liquid graphite and glass beads. The graphite will burn away, but the glass beads will
remain, making the sensor easier to remove. New or service sensors will already have the
compound applied to the threads. If a sensor is removed from an engine, and, if for any reason it is
to be reinstalled, the threads must have anti-seize compound applied before reinstallation.
1. Coat the threads of the HO2S with anti-seize compound P/N 5613695, or equivalent if
necessary. 2. Install the sensor in the engine, and tighten to 41 Nm (30 ft lb). 3. Connect the
electrical connector. 4. Lower vehicle. 5. Connect the negative battery cable.
NOTICE: The system has a learning ability which allows it to make corrections for minor variations
in the fuel system to improve driveability. When the battery is disconnected the computer's memory
is cleared and the learning process has to begin all over again. A change may be noticed in the
driving performance of the vehicle. To reset the vehicles learning ability, make sure the engine is at
operating temperature and operate the vehicle at part throttle, moderate acceleration, and idle
conditions, until normal performance returns.
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Left Front Of Engine
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Information and Instructions
Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Power Steering Pressure Switch Circuit.
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Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
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Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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Throttle Position Sensor: Locations
Component Location - Pictorial View
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Component Location - Pictorial View
Throttle Body
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and Instructions
Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Throttle Position Sensor Circuit.
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Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
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RH Side Of Steering Column
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Component Locations > Page 4561
RH Side Of Steering Column
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Diagram Information and Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Diagram Information and Instructions > Page 4573
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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4596
Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Rear Of Transmission
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Vehicle Speed Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Vehicle Speed Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Instructions > Page 4624
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Instructions > Page 4625
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Instructions > Page 4626
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Instructions > Page 4627
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Instructions > Page 4628
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Instructions > Page 4629
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Instructions > Page 4630
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Instructions > Page 4632
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Sensors and Switches Computers and Control Systems > Vehicle Speed Sensor > Component Information > Description and Operation > General
Description
Vehicle Speed Sensor: Description and Operation General Description
Vehicle Speed Sensor (2WD)
The Vehicle Speed Sensor (VSS) is a pulse counter type input that informs the Powertrain Control
Module (PCM) how fast the vehicle is being driven. The VSS system uses an inductive sensor
mounted in the tail housing of the transmission and a toothed reluctor wheel on the tail shaft. As
the reluctor rotates, the teeth alternately interfere with the magnetic field of the sensor creating an
induced voltage pulse.
The VSS produces an AC voltage signal that increases with vehicle speed. The PCM processes
this signal and sends it to the instrument panel, EVO module, chime module and cruise control
module on CKT 817. A malfunction in the VSS system could set Diagnostic Trouble Code (DTC) 24
or DTC 72.
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Description > Page 4635
Vehicle Speed Sensor: Description and Operation Circuit Operation
The Speed Sensor Circuit consists of a magnetic type sensor and wiring. Gear teeth pressed on
the Transmission Output Shaft induce an alternating current in the sensor. This sensor generates a
sine wave output with a frequency proportional to vehicle speed. The Powertrain Control Module
(PCM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses
per mile at the DK GRN/WHT wire (CKT 817) which feeds the Turn Signal Alarm, Power Steering
Control Module, Instrument Cluster, Cruise Control Module and Radio (Chev only).
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Inspection and Diagnostic Overview
Vehicle Speed Sensor: Initial Inspection and Diagnostic Overview
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
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Inspection and Diagnostic Overview > Page 4638
Vehicle Speed Sensor: Symptom Related Diagnostic Procedures
Chart #1 Speedometer And Cruise Control Inoperative; Code 24 Not Set
Symptom Table
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Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Throttle Position Sensor >
Component Information > Specifications
Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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Component Information > Specifications > Page 4642
Throttle Position Sensor: Locations
Component Location - Pictorial View
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Component Information > Specifications > Page 4643
Component Location - Pictorial View
Throttle Body
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Component Information > Diagrams > Diagram Information and Instructions
Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Component Information > Diagrams > Diagram Information and Instructions > Page 4646
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Component Information > Diagrams > Diagram Information and Instructions > Page 4647
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Component Information > Diagrams > Diagram Information and Instructions > Page 4648
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Component Information > Diagrams > Diagram Information and Instructions > Page 4651
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Component Information > Diagrams > Diagram Information and Instructions > Page 4652
Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Throttle Position Sensor Circuit.
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Component Information > Diagrams > Page 4678
Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Switch/Sensor, A/T > Component Information > Locations > Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
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RH Side Of Steering Column
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RH Side Of Steering Column
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Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 4696
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Component Information > Locations
Rear Of Transmission
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Component Information > Diagrams > Diagram Information and Instructions
Vehicle Speed Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Vehicle Speed Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4749
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4750
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4751
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4752
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4753
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4754
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4755
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4756
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Description and Operation > General Description
Vehicle Speed Sensor: Description and Operation General Description
Vehicle Speed Sensor (2WD)
The Vehicle Speed Sensor (VSS) is a pulse counter type input that informs the Powertrain Control
Module (PCM) how fast the vehicle is being driven. The VSS system uses an inductive sensor
mounted in the tail housing of the transmission and a toothed reluctor wheel on the tail shaft. As
the reluctor rotates, the teeth alternately interfere with the magnetic field of the sensor creating an
induced voltage pulse.
The VSS produces an AC voltage signal that increases with vehicle speed. The PCM processes
this signal and sends it to the instrument panel, EVO module, chime module and cruise control
module on CKT 817. A malfunction in the VSS system could set Diagnostic Trouble Code (DTC) 24
or DTC 72.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Description and Operation > General Description > Page 4759
Vehicle Speed Sensor: Description and Operation Circuit Operation
The Speed Sensor Circuit consists of a magnetic type sensor and wiring. Gear teeth pressed on
the Transmission Output Shaft induce an alternating current in the sensor. This sensor generates a
sine wave output with a frequency proportional to vehicle speed. The Powertrain Control Module
(PCM) converts this signal to an output that is switched to ground at a frequency of 4000 pulses
per mile at the DK GRN/WHT wire (CKT 817) which feeds the Turn Signal Alarm, Power Steering
Control Module, Instrument Cluster, Cruise Control Module and Radio (Chev only).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Testing and Inspection > Initial Inspection and Diagnostic Overview
Vehicle Speed Sensor: Initial Inspection and Diagnostic Overview
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Computers and Control Systems > Vehicle Speed Sensor >
Component Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 4762
Vehicle Speed Sensor: Symptom Related Diagnostic Procedures
Chart #1 Speedometer And Cruise Control Inoperative; Code 24 Not Set
Symptom Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Check Valve > Component Information > Specifications
Air Injection Check Valve: Specifications
Check Valves 17 ft.lb
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Check Valve > Component Information > Specifications > Page 4768
AIR System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Check Valve > Component Information > Specifications > Page 4769
Air Injection Check Valve: Description and Operation
The check valves prevent back flow of exhaust gases into the pump in the event of an exhaust
backfire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Check Valve > Component Information > Specifications > Page 4770
Air Injection Check Valve: Testing and Inspection
A check valve should be inspected whenever the hose is disconnected from a check valve or
whenever check valve failure is suspected. (An Air Injection Reaction (AIR) pump that had become
inoperative and had shown indications of having exhaust gases in the outlet port would indicate
check valve failure.) Blow through the check valve (toward the cylinder head) then attempt to suck
back through the check valve. Flow should only be in one direction (toward the exhaust manifold).
Replace valve which does not operate properly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Check Valve > Component Information > Specifications > Page 4771
Air Injection Check Valve: Service and Repair
Left Side Air
LEFT SIDE
Remove or Disconnect 1. Check valve clamp. 2. Hose from check valve. 3. Left check valve pipe.
4. Unscrew check valve from air injection pipe.
Install or Connect 1. Screw check valve onto air injection pipe.
Tighten Valve to 23 Nm (17 lb ft.).
2. Air pipe to exhaust manifold. 3. Air hose to check valve. 4. Check valve clamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Check Valve > Component Information > Specifications > Page 4772
Right Side Air
RIGHT SIDE
Remove or Disconnect 1. Clamp and air hoses from AIR system right pipe. 2. Check valve clamp.
3. Right check valve pipe. 4. Unscrew check valve from air injection pipe.
Install or Connect 1. Screw check valve onto air injection pipe.
Tighten Valve to 23 Nm (17 lb ft.).
2. Check valve pipe and clamp. 3. Check AIR system for proper operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Hose/Tube > Component Information > Locations
AIR System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Hose/Tube > Component Information > Locations > Page 4776
Air Injection Hose/Tube: Testing and Inspection
INSPECT
^ Inspect hoses and/or pipes for deterioration or holes.
^ Inspect all hoses or pipe connections, and clamp torque.
^ Inspect hose and pipe routing. Interference may cause wear.
^ If a leak on the pressure side is suspected, or if a hose or pipe has been disconnected on the
pressure side, the connections should be checked for leaks with a soapy water solution. With the
Air Injection Reaction (AIR) pump running, bubbles will form if a leak exists.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Hose/Tube > Component Information > Locations > Page 4777
Air Injection Hose/Tube: Service and Repair
Air System
REMOVE OR DISCONNECT
1. Clamp and air hose to check valve both sides, from cross under pipe. 2. Clamp and air hose to
air pump, from cross under pipe. 3. Raise vehicle. 4. Fasteners from air cross under pipe bracket,
both sides. 5. Cut cross under pipe near center of oil pan to aid in removal. 6. Cross under pipe.
INSTALL OR CONNECT
1. Cross under pipe. New cross under pipe must be cut similarly to old pipe before installation. 2.
Use appropriate length of 5/8 heater hose to join both halves of cross under pipe. Clamp both ends
of hose securely with stainless steel clamps. 3. Fasteners to AIR cross under pipe bracket, both
sides. 4. Lower vehicle. 5. Clamp and AIR hose from AIR pump to cross under pipe 6. Clamp and
AIR hose from check valve, both sides, to cross under pipe. 7. Check AIR system for proper
operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump > Component Information > Specifications
Air Injection Pump: Specifications Reactor Pump Torque
Reactor Pump Torque
Air Injection Reactor (AIR) Pump 50 in.lb
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump > Component Information > Locations > Air Pump Assembly
AIR System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump > Component Information > Locations > Air Pump Assembly > Page 4783
Left Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump > Component Information > Locations > Page 4784
Air Injection Pump: Description and Operation
The Air Injection Reaction (AIR) pump is mounted to the lower left front of the engine and supplies
the air to the AIR system. The electric air pump pressurizes air from the engine air cleaner and
pumps it to the check valves near the exhaust manifolds.
The AIR pump is controlled by the Powertrain Control Module (PCM). Battery voltage to the AIR
pump is controlled by the AIR pump relay. An integral stop valve prevents air flow through the
pump during "OFF" periods. When the PCM provides a ground circuit for the secondary AIR pump
relay, battery voltage is allowed to power up the AIR pump and integral stop valve. The AIR pump
motor is protected by a 20 amp fuse and has its own remote ground.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump > Component Information > Locations > Page 4785
Air Injection Pump: Testing and Inspection
The Air Injection Reaction (AIR) pump is a regenerative turbine type which is permanently
lubricated and requires no periodic maintenance. The engine should be at normal operating
temperature in neutral at idle. Using the scan tool select "Miscellaneous Test" then "Output Test."
Select "AIR System" in "Output Test" directory. Select Heated Oxygen Sensor (HO2S) voltages for
both Bank 1 and Bank 2 HO2S. Enable the "Output Test" for the AIR system. The "Output Test" will
energize the AIR pump for only 5 seconds. When the output Test" is enabled, the HO2S voltages
for both sensors should remain under 300 mV because air is being directed to the exhaust ports. If
the HO2S voltages remain low during the "Output Test," the AIR pump and integral stop valve are
operating satisfactorily.
If the HO2S voltage does not remain low when the "Output Test" is commanded "ON," proceed as
follows.
1. For a seized AIR pump. 2. Hoses, tubes and all connections for leaks and proper routing. 3. For
air flow going to the exhaust ports. 4. AIR pump for proper mounting.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump > Component Information > Locations > Page 4786
Air Injection Pump: Service and Repair
Air Pump Service
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector from Air Injection Reaction (AIR) pump. 3. Outlet
and inlet hoses. 4. Three electric air pump mounting bolts from bracket.
INSTALL OR CONNECT:
1. Electric air pump mounting bracket to electric air pump assembly. 2. Three mounting bolts.
Tighten Mounting bolts to 5.6 N-m (50 lb in.).
3. Outlet and inlet hoses to pump. 4. Electric connector to air pump. 5. Negative battery cable. 6.
Check AIR system for proper operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump Relay > Component Information > Locations
Air Injection Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Air Injection Reaction (AIR) System
<--> [Air Injection] > Air Injection Pump Relay > Component Information > Locations > Page 4790
Air Injection Pump Relay: Description and Operation
Chart C-6
The Powertrain Control Module (PCM) controls operation of the electric air pump relay which in
turn controls air availability to the air injection system. The PCM completes the ground to the coil
side of the relay. The relay in turn activates the electric air pump and the integral stop valve.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Catalytic Converter > Component
Information > Locations
Catalytic Converter Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Evaporative Emissions System >
Canister Purge Solenoid > Component Information > Locations > Canister Purge Control Solenoid
Canister Purge Solenoid
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Evaporative Emissions System >
Canister Purge Solenoid > Component Information > Locations > Canister Purge Control Solenoid > Page 4799
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Evaporative Emissions System >
Canister Purge Solenoid > Component Information > Diagrams > Diagram Information and Instructions
Canister Purge Solenoid: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Evaporative Emissions System >
Canister Purge Solenoid > Component Information > Diagrams > Diagram Information and Instructions > Page 4802
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Canister Purge Solenoid: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Evaporative Canister Purge Solenoid Circuit
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Canister Purge Solenoid: Description and Operation
Canister Purge Solenoid
This system has a remote mounted canister purge control solenoid valve. The Powertrain Control
Module (PCM) operates this solenoid valve to control vacuum to the canister. Under cold engine or
idle conditions, the solenoid valve is closed, which prevents vacuum from being applied to the
canister. The PCM activates (or opens) the solenoid valve and allows purge when:
^ Engine is warm.
^ After the engine has been running a specified period of time.
^ Above a specified road speed.
^ Above a specified throttle opening.
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Canister Purge Solenoid > Component Information > Diagrams > Page 4835
Canister Purge Solenoid: Service and Repair
Canister Purge Solenoid
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Fastener from ignition test connector. 3. Electrical connector and
hoses from solenoid. 4. Bracket and solenoid from intake manifold.
INSTALL OR CONNECT
1. Solenoid to intake manifold
Tighten ^
Bolt to intake manifold to 5.8 Nm (52 lb in.).
2. Hoses and electrical connector to solenoid 3. Ignition test connector to bracket 4. Negative
battery cable
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Evaporative Check Valve > Component Information > Locations
Canister And Valve Location
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Evaporative Check Valve: Description and Operation
EVAP Pressure Control Valve
This system uses an in-line Evaporative Emissions (EVAP) pressure control valve as a pressure
relief valve. When vapor pressure in the tank exceeds approximately 5 kPa (.7 psi) the diaphragm
valve opens, allowing vapors to vent to the canister. A 1.14 mm (0.045 inch) orifice in the passage
leading to the canister tube causes pressure to drop slowly, preventing the valve from oscillating
(buzzing). When the tank pressure drops below 5 kPa (.7 psi), the valve closes causing vapors to
be held in the fuel tank.
RESULTS OF INCORRECT OPERATION
^ Poor idle, stalling and poor driveability can be caused by: Inoperative purge solenoid valve.
- Damaged canister.
- Hoses split, cracked and, or not connected to the proper tubes.
^ Evidence of fuel loss or fuel vapor odor can be caused by: Liquid fuel leaking from fuel lines.
- Cracked or damaged canister.
- Inoperative canister control valve.
- Disconnected, misrouted, kinked, deteriorated or damaged vapor hoses, or control hoses.
If the solenoid valve is open. or is not receiving power, the canister can purge to the intake
manifold at the incorrect time. This can allow extra fuel during warm-up, which can cause rough or
unstable idle.
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Evaporative Check Valve: Testing and Inspection
With a hand vacuum pump, apply approximately 51 kPa (15" Hg) to the control vacuum tube. After
ten seconds, there should be at least 17 kPa (5" Hg) vacuum remaining. Be sure the hand vacuum
pump being used does not have an internal leak and the hose connections to control vacuum tube
and pump are secure. If after 10 seconds there is less than 17 kPa (5" Hg) vacuum, the valve must
be replaced. With 51 kPa (15" Hg) vacuum still applied to the control vacuum tube, attach a short
piece of hose to the valve's tank tube side. Blow into the tube. You should feel the air pass through
the valve. If air does not pass through, the valve must be replaced.
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Evaporative Emission Control Canister > Component Information > Locations
Canister And Valve Location
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Evaporative Emission Control Canister > Component Information > Locations > Page 4844
Evaporative Emission Control Canister: Description and Operation
Fuel Vapor Canister
The Evaporative Emission (EVAP) control system uses a 1500 cc charcoal canister to absorb fuel
vapors from the gas tank. When gasoline vapor builds enough to overcome the spring tension of
the EVAP pressure control valve, the vapor will flow to the canister where it is absorbed and stored
by the charcoal. Under certain operating conditions the Powertrain Control Module (PCM) will
command the purge solenoid valve to open. This allows the vapor to flow into the intake manifold
for combustion.
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Evaporative Emission Control Canister > Component Information > Locations > Page 4845
Evaporative Emission Control Canister: Testing and Inspection
Perform a visual inspection of the Canister, replace if cracked or damaged.
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Evaporative Emission Control Canister: Service and Repair
Canister And Valve Location
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Raise vehicle 3. Access panel. 4. Hoses from canister. 5. Canister
from bracket. 6. Canister from vehicle.
INSTALL OR CONNECT
1. Canister to vehicle. 2. Canister to bracket. 3. Hoses to canister. 4. Access panel. 5. Lower
vehicle. 6. Negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Evaporative Emissions System >
Evaporative Emissions Hose > Component Information > Technical Service Bulletins > Fuel Odor - Right Hand Side of
Passenger Compartment
Evaporative Emissions Hose: Technical Service Bulletins Fuel Odor - Right Hand Side of
Passenger Compartment
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 67-65-18
Date: March, 1996
Subject: Fuel Odor Near the Right Hand Side of the Passenger Compartment (Reroute Canister
Fresh Air Hose)
Models: 1994-95 Buick Roadmaster 1994-95 Cadillac Fleetwood 1994-95 Chevrolet Caprice,
Impala SS with 4.3L, 5.7L Engine (VINs W, P - RPOs L99, LT1) and with Automatic
HYDRA-MATIC 4L60-E Transmission
Condition
Some owners may comment of fuel odor near the RH (Right Hand) side of the passenger
compartment.
Cause
Under high ambient temperatures and slow speed driving conditions, (i.e. stop and go traffic) fuel
odor from the canister fresh air inlet hose located in the RH side fender well may carryover to RH
side of the passenger compartment.
Correction
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Evaporative Emissions Hose > Component Information > Technical Service Bulletins > Fuel Odor - Right Hand Side of
Passenger Compartment > Page 4851
Relocate the canister fresh air hose to the front radiator support. See Figure 1.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Labor Time
T-2495 0.4 hr
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Evaporative Fuel Vapor Return Hose > Component Information > Description and Operation
Evaporative Fuel Vapor Return Hose: Description and Operation
The evaporative emission (EVAP) pipe extends from the fuel sender assembly to the evaporative
emission canister. It is made up of nylon pipe and is connected to the fuel sender assembly and the
evaporative emission canister with fuel resistant rubber hoses.
WARNING: To Reduce the Risk of Fire and Personal Injury:
^ Always cover nylon vapor pipes with a wet towel before using a torch near them. Also, never
expose the vehicle to temperatures higher then 115° C (239° F) for more than one hour, or more
than 90° C (194° F) for any extended period.
^ Take care not to nick or scratch the nylon vapor pipes. If damaged, they must be replaced.
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Evaporative Fuel Vapor Return Hose > Component Information > Description and Operation > Page 4855
Evaporative Fuel Vapor Return Hose: Service and Repair
Evaporative Emissions (EVAP) Pipe Replacement
NOTICE:
^ If nylon pipes becomes kinked, and cannot be straightened, they must be replaced.
^ Do Not attempt to repair sections of nylon pipes. If damaged, replace.
^ When replacing evaporative emissions (EVAP) pipes, always replace them with original
equipment or parts that meet the GM specifications for those parts.
^ When replacing EVAP hoses always replace them with original equipment or parts meeting GM
specifications, use only reinforced fuel-resistant hose which is identified with the word
"Fluoroelastomer" or "GM 6163-M" on the hose.
REMOVE OR DISCONNECT
1. Raise vehicle. 2. Fuel feed, return, and EVAP pipe underbody retainer.
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3. EVAP pipe clamp at fuel sender assembly. 4. EVAP pipe retaining clips.
^ Note position of EVAP pipe for installation.
5. Lower vehicle. 6. EVAP pipe hose end clamp at EVAP canister. 7. Forward pipe assembly
retaining clips. 8. EVAP pipe.
INSTALL OR CONNECT
1. Insert rear end of EVAP pipe into top forward frame hole. Load until formed pipe/conduit reaches
into hole. 2. Forward pipe assembly retaining clips. 3. EVAP pipe hose end to EVAP canister.
Secure with clamp. 4. Raise vehicle. 5. Position new EVAP pipe in same position as noted during
disassembly and install retaining clips. 6. EVAP pipe clamp at fuel sender assembly. 7. Fuel feed,
return, and EVAP pipe underbody retainer. 8. Lower vehicle.
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Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Control Solenoid > Component Information > Specifications
EGR Control Solenoid: Specifications Bracket Nut Torque
Bracket Nut Torque
Solenoid Valve and Bracket Nut 25 ft.lb
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Control Solenoid > Component Information > Specifications > Page 4861
Engine Left Side Upper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Locations
EGR Solenoid Valve
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions
EGR Electronic Vacuum Regulator Solenoid: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4867
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4869
Fig.1-Symbols (Part 1 Of 3)
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4870
Fig.2-Symbols (Part 2 Of 3)
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4871
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4872
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4873
EGR Electronic Vacuum Regulator Solenoid: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4874
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Page 4875
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Page 4877
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Page 4893
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4894
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4895
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4896
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4897
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Diagram Information and Instructions >
Page 4898
Exhaust Gas Recirculation (EGR) Circuit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Page 4899
EGR Electronic Vacuum Regulator Solenoid: Description and Operation
The Exhaust Gas Recirculation (EGR) vacuum control has a vacuum control solenoid that is
controlled by Pulse Width Modulation (PWM). This means that the Powertrain Control Module
(PCM) turns the solenoid "OFF" and "ON" many times a second and varies the amount of "ON"
time (pulse width) to vary the amount ported manifold vacuum to the EGR valve.
The PCM uses RPM and information from the following sensors to regulate the EGR solenoid
valve:
^ Engine Coolant Temperature (ECT) sensor.
^ Intake Air Temperature (IAT) sensor.
^ Throttle Position (TP) sensor.
^ Manifold Absolute Pressure (MAP) sensor.
^ Park/Neutral Position (PNP) switch.
^ Vehicle Speed Sensor (VSS).
Grounding the Data Link Connector (DLC) output / field service enable terminal with the ignition
"ON" and the engine not running will energize the solenoid valve and allow vacuum to the EGR
valve.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Electronic Vacuum Regulator Solenoid > Component Information > Diagrams > Page 4900
EGR Electronic Vacuum Regulator Solenoid: Service and Repair
EGR Solenoid Valve
REMOVE OR DISCONNECT
1. Negative battery cable 2. Electrical connector 3. Vacuum hoses 4. Nut and solenoid
INSTALL OR CONNECT
1. Solenoid and bracket
Tighten Nut to 34 Nm (25 lb ft.).
2. Vacuum hoses 3. Electrical connector 4. Negative battery cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Valve > Component Information > Specifications
EGR Valve: Specifications
Exhaust Gas Recirculation Valve Bolts 16 ft.lb
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Valve > Component Information > Specifications > Page 4904
EGR Valve Service
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Valve > Component Information > Specifications > Page 4905
EGR Valve: Application and ID
EGR Valve Identification
EXHAUST GAS RECIRCULATION (EGR) VALVE IDENTIFICATION
^ Negative backpressure EGR valves are stamped with a "N" on the top side of the valve after the
part number.
^ Positive backpressure EGR valves are stamped with a "P" on the top side of the valve after the
part number.
^ Port EGR valves will have no identification stamped after the part number.
When replacing an EGR valve, always check for correct part number in the part catalog or
supplemental bulletins.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Valve > Component Information > Specifications > Page 4906
EGR Valve: Description and Operation
The Exhaust Gas Recirculation (EGR) valve used on this engine is a negative backpressure valve.
It varies the amount of exhaust gas flow into the manifold depending on manifold vacuum and
variations in exhaust backpressure. The diaphragm on this EGR valve has an internal vacuum
bleed hole which is held closed by a small spring when there is no exhaust backpressure the
amount of vacuum to the valve is controlled by an Powertrain Control Module (PCM) controlled
solenoid valve. Engine vacuum opens the EGR valve again the pressure of a large spring. When
vacuum combines with negative exhaust backpressure, the vacuum bleed hole opens and the EGR
valve closes.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Valve > Component Information > Specifications > Page 4907
EGR Valve: Testing and Inspection
Too much Exhaust Gas Recirculation (EGR) flow dilutes the fresh intake air/fuel mixture, causing
the engine to run roughly or stall. With too much EGR flow (at idle, cruise, or cold operation) tends
to weaken combustion and may result in any of the following conditions:
^ Engine stops after cold start.
^ Engine stops at idle after deceleration.
^ Vehicle surges during cruise.
^ Rough idle.
Too little or no EGR flow allows combustion temperatures to get too high during acceleration and
load conditions. This could cause: ^
Spark knock (detonation).
^ Engine overheating.
^ Emission test failure.
For diagnosis of the EGR system refer to Computers and Control Systems / System Diagnosis /
Procedures / Diagnostic chart C-7.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Exhaust Gas Recirculation > EGR
Valve > Component Information > Specifications > Page 4908
EGR Valve: Service and Repair
EGR Valve Service
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Vacuum line. 3. Retaining nuts. 4. Exhaust Gas Recirculation (EGR)
valve.
INSPECT
If EGR passages in the inlet manifold indicate excessive build-up of deposits, the passages should
be cleaned. Care should be taken to ensure that all loose particles are completely removed to
prevent them from clogging the EGR valve or from being ingested into the engine.
CLEAN
1. With a wire wheel, buff the exhaust deposits from the mounting surface and around the valve. 2.
Look for exhaust deposits in the valve outlet. Remove deposit build-up with a screwdriver. 3. Clean
mounting surfaces of intake manifold and valve assembly.
INSTALL OR CONNECT
1. EGR valve on intake manifold using a new gasket
Tighten Bolts to 22 Nm (16 lb ft.).
2. Vacuum hose to valve 3. Negative battery cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Positive Crankcase Ventilation >
Positive Crankcase Ventilation Valve > Component Information > Locations
Crankcase Ventilation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Positive Crankcase Ventilation >
Positive Crankcase Ventilation Valve > Component Information > Locations > Page 4913
Positive Crankcase Ventilation Valve: Testing and Inspection
If an engine is idling rough, check for a clogged positive crankcase ventilation (PCV) valve or
plugged hose. Replace as required. Use the following procedure:
1. Remove PCV valve from intake manifold. 2. Run the engine at idle. 3. Place your thumb over
end of valve to check for vacuum. If there is no vacuum at the valve, check for plugged hoses or
manifold port, or PCV
valve. Replace plugged or deteriorated hoses.
4. Turn "OFF" the engine and remove PCV valve. Shake valve and listen for the rattle of check
needle inside the valve. If valve does not rattle,
replace valve.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Positive Crankcase Ventilation >
Positive Crankcase Ventilation Valve > Component Information > Locations > Page 4914
Positive Crankcase Ventilation Valve: Service and Repair
Crankcase Ventilation
REMOVE OR DISCONNECT
1. Remove positive crankcase ventilation (PCV) valve from valve cover. 2. Remove PCV valve
from vacuum hose.
INSPECT
1. Ensure hoses and vacuum passages are free of obstruction. Ensure PCV valve is not stuck or
bound.
INSTALL OR CONNECT:
1. Reverse removal procedures to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Relays and Modules - Emission
Control Systems > Air Injection Pump Relay > Component Information > Locations
Air Injection Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Emission Control Systems > Relays and Modules - Emission
Control Systems > Air Injection Pump Relay > Component Information > Locations > Page 4919
Air Injection Pump Relay: Description and Operation
Chart C-6
The Powertrain Control Module (PCM) controls operation of the electric air pump relay which in
turn controls air availability to the air injection system. The PCM completes the ground to the coil
side of the relay. The relay in turn activates the electric air pump and the integral stop valve.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure > Diagnostic
Connector - Fuel Pump > Component Information > Locations
Diagnostic Connector - Fuel Pump: Locations
The fuel pump test connector is located in the engine compartment near the A/C accumulator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure > Fuel Pressure
Test Port > Component Information > Locations
Fuel Pressure Test Port
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure > Fuel Pressure
Test Port > Component Information > Locations > Page 4928
Fuel Pressure Test Port: Service and Repair
Fuel Test Port Valve
CLEAN
^ Area around fuel pressure connection with GM X-3OA or equivalent.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery System / Service and Repair.
3. Fuel pressure connection valve assembly.
INSTALL OR CONNECT
1. Fuel pressure connection valve assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten
seconds. Again turn to "ON" position, and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Release >
System Information > Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Speed > System
Information > Specifications
Idle Speed: Specifications
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Speed > System
Information > Specifications > Page 4935
Idle Speed: Adjustments
The Idle Speed is controlled by the Powertrain Control Module and is not adjustable. If Idle Speed
is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air/Fuel Mixture > System
Information > Specifications
Air/Fuel Mixture: Specifications
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air/Fuel Mixture > System
Information > Specifications > Page 4939
Air/Fuel Mixture: Adjustments
The Air / Fuel mixture is controlled by the Powertrain Control Module and is not adjustable. If Air /
Fuel mixture is incorrect begin diagnosis at Powertrain Management / System Diagnosis / Flow of
Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Recalls for Accelerator Controls: > 95C23 >
Jun > 95 > Recall - Excessive Friction in Accelerator Pedal
Technical Service Bulletin # 95C23 Date: 950602
Recall - Excessive Friction in Accelerator Pedal
CHEVROLET No: 95-C-23
Issued: 06/01/95
Subject: PRODUCT SAFETY CAMPAIGN 95-C-23 ACCELERATOR PEDAL ASSEMBLY
Model and Year: 1994-1995 CHEVROLET CAPRICE/IMPALA
TO: All Chevrolet/Geo Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle which is
subject to a recall campaign of this type must be adequately repaired within a reasonable time after
the owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a
vehicle is prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonably equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solutions, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the attached copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact the National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1994-95 Chevrolet Caprice and Impala model vehicles
may have been built with a defective accelerator pedal assembly which causes the vehicles to fail
to conform to the requirements of the Federal Motor Vehicle Safety Standard (FMVSS) 124,
"Accelerator Control Systems". Under some circumstances at low temperatures, there may be
excessive friction in the accelerator pedal assembly. If there is excessive friction in the pedal
assembly, in the event of a failure of a throttle return spring the engine speed may not return to idle
as specified in FMVSS 124.
To correct this condition, dealers are to replace the accelerator pedal assembly.
VEHICLES INVOLVED
Involved are certain 1994-95 Chevrolet Caprice a Impala model vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign.
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with the
campaign bulletin has no involved vehicles currently assigned.
Parts Information
A preshipment of parts will be sent to involved dealers the week of May 29, 1995. Preshipment
parts will be charged to the dealers, open parts account.
Additional parts required to complete this campaign are to be obtained from General Motors
Service Parts Operations (GMSPO). To ensure these parts will be obtained as soon as possible,
they should be ordered from GMSPO on a "C.I.O." order with no special instruction code, but on an
advise code (2). All Goodwrench parts system test dealers should order on a "VIP" order.
Quantity
Part Number Description Vehicle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Recalls for Accelerator Controls: > 95C23 >
Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4948
12553725 Accelerator Pedal Assembly 1
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the owners letter accompanying this bulletin. Campaign
follow-up cards should not be used for this purpose, since the owner may not as yet have received
the notification letter
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory, or is in
your dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
This bulletin is notice to you that the new motor vehicles included in this campaign may not comply
with the standard identified above Under Section 108 of the National Traffic and Motor Vehicle
Safety Act, it is illegal for a dealer to sell a new motor vehicle which the dealer knows does not
comply with an applicable Federal Motor Vehicle Safety Standard. As a consequence, if you sell
any of these motor vehicles without first performing the campaign correction, your dealership may
be subject to a civil penalty up to $1,000 for each such sale.
Service Procedure
1. Place ignition in full lock position and set parking brake.
2. Disconnect accelerator cable from accelerator pedal assembly.
3. Remove three (3) screws from accelerator pedal assembly.
4. Remove instrument panel/body harness connector mounting screws and connector from
accelerator pedal assembly
5. Remove accelerator pedal assembly from dash panel.
6. Install instrument panel/body harness connector mounting screws and connector to new
accelerator Pedal assembly. Torque to 7 Nm (62 lb. in).
7. Install new accelerator pedal assembly to dash panel. Torque to 2.8 Nm (25 lb. in).
Important:
Insure accelerator pedal assembly plate is positioned flat against dash panel. Other material such
as carpeting, insulation, etc. must NOT interfere with the accelerator pedal assembly plate and the
dash panel.
The floor carpet assembly in pedal area must be positioned to lay flat and be free of wrinkles and
bunches.
8. Connect accelerator cable to accelerator pedal assembly.
TO INSURE THAT THE THROTTLE SYSTEM OPERATES PROPERLY AFTER THE ABOVE
SERVICE PROCEDURE, PERFORM AN INSPECTION OF THE FOLLOWING THROTTLE
COMPONENTS:
9. Cable assembly must not be kinked or damaged in any way during assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Recalls for Accelerator Controls: > 95C23 >
Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4949
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Recalls for Accelerator Controls: > 95C23 >
Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4950
10. Inspect the accelerator cable and throttle return spring at the throttle lever on the throttle body.
See illustrations.
Reposition accelerator cable and throttle return spring if necessary.
11. Check for complete throttle opening and closing positions by operating accelerator pedal.
Throttle must operate freely without binding between full closed throttle and full open throttle.
12. Install Campaign Identification Label.
Campaign ID Label & Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Each "Campaign Identification Label", is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
"Campaign Identification Labels" can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean, dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Recalls for Accelerator Controls: > 95C23 >
Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4951
Net price plus 40% of all parts required for the repair.
Refer to the Chevrolet Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1994-95 Chevrolet Caprice and Impala model vehicles
may have been built with a defective accelerator pedal assembly which causes the vehicles to fail
to conform to the requirements of the Federal Motor Vehicle Safety Standard (FMVSS) 124
"Accelerator Control Systems". Under some circumstances at low temperatures, there may be
excessive friction in the accelerator pedal assembly. If there is excessive friction in the pedal
assembly, in the event of a failure of a throttle return spring the engine speed may not return to idle
as specified in FMVSS 124.
WHAT WE WILL DO
To correct this condition, it is necessary to install a new accelerator pedal assembly. This service
will be performed for you at no charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date and so the
dealer may order the necessary parts for the repair. Instructions for making this correction have
been sent to your dealer. The labor time necessary to perform this service correction is
approximately 20 minutes. Please ask your dealer if you wish to know how much additional time
will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the Administrator, National Traffic Safety Administration, 400 Seventh Street,
S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your safety and continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Accelerator
Controls: > 95C23 > Jun > 95 > Recall - Excessive Friction in Accelerator Pedal
Technical Service Bulletin # 95C23 Date: 950602
Recall - Excessive Friction in Accelerator Pedal
CHEVROLET No: 95-C-23
Issued: 06/01/95
Subject: PRODUCT SAFETY CAMPAIGN 95-C-23 ACCELERATOR PEDAL ASSEMBLY
Model and Year: 1994-1995 CHEVROLET CAPRICE/IMPALA
TO: All Chevrolet/Geo Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle which is
subject to a recall campaign of this type must be adequately repaired within a reasonable time after
the owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a
vehicle is prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonably equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solutions, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the attached copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact the National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1994-95 Chevrolet Caprice and Impala model vehicles
may have been built with a defective accelerator pedal assembly which causes the vehicles to fail
to conform to the requirements of the Federal Motor Vehicle Safety Standard (FMVSS) 124,
"Accelerator Control Systems". Under some circumstances at low temperatures, there may be
excessive friction in the accelerator pedal assembly. If there is excessive friction in the pedal
assembly, in the event of a failure of a throttle return spring the engine speed may not return to idle
as specified in FMVSS 124.
To correct this condition, dealers are to replace the accelerator pedal assembly.
VEHICLES INVOLVED
Involved are certain 1994-95 Chevrolet Caprice a Impala model vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign.
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with the
campaign bulletin has no involved vehicles currently assigned.
Parts Information
A preshipment of parts will be sent to involved dealers the week of May 29, 1995. Preshipment
parts will be charged to the dealers, open parts account.
Additional parts required to complete this campaign are to be obtained from General Motors
Service Parts Operations (GMSPO). To ensure these parts will be obtained as soon as possible,
they should be ordered from GMSPO on a "C.I.O." order with no special instruction code, but on an
advise code (2). All Goodwrench parts system test dealers should order on a "VIP" order.
Quantity
Part Number Description Vehicle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Accelerator
Controls: > 95C23 > Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4957
12553725 Accelerator Pedal Assembly 1
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the owners letter accompanying this bulletin. Campaign
follow-up cards should not be used for this purpose, since the owner may not as yet have received
the notification letter
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory, or is in
your dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
This bulletin is notice to you that the new motor vehicles included in this campaign may not comply
with the standard identified above Under Section 108 of the National Traffic and Motor Vehicle
Safety Act, it is illegal for a dealer to sell a new motor vehicle which the dealer knows does not
comply with an applicable Federal Motor Vehicle Safety Standard. As a consequence, if you sell
any of these motor vehicles without first performing the campaign correction, your dealership may
be subject to a civil penalty up to $1,000 for each such sale.
Service Procedure
1. Place ignition in full lock position and set parking brake.
2. Disconnect accelerator cable from accelerator pedal assembly.
3. Remove three (3) screws from accelerator pedal assembly.
4. Remove instrument panel/body harness connector mounting screws and connector from
accelerator pedal assembly
5. Remove accelerator pedal assembly from dash panel.
6. Install instrument panel/body harness connector mounting screws and connector to new
accelerator Pedal assembly. Torque to 7 Nm (62 lb. in).
7. Install new accelerator pedal assembly to dash panel. Torque to 2.8 Nm (25 lb. in).
Important:
Insure accelerator pedal assembly plate is positioned flat against dash panel. Other material such
as carpeting, insulation, etc. must NOT interfere with the accelerator pedal assembly plate and the
dash panel.
The floor carpet assembly in pedal area must be positioned to lay flat and be free of wrinkles and
bunches.
8. Connect accelerator cable to accelerator pedal assembly.
TO INSURE THAT THE THROTTLE SYSTEM OPERATES PROPERLY AFTER THE ABOVE
SERVICE PROCEDURE, PERFORM AN INSPECTION OF THE FOLLOWING THROTTLE
COMPONENTS:
9. Cable assembly must not be kinked or damaged in any way during assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Accelerator
Controls: > 95C23 > Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4958
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Accelerator
Controls: > 95C23 > Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4959
10. Inspect the accelerator cable and throttle return spring at the throttle lever on the throttle body.
See illustrations.
Reposition accelerator cable and throttle return spring if necessary.
11. Check for complete throttle opening and closing positions by operating accelerator pedal.
Throttle must operate freely without binding between full closed throttle and full open throttle.
12. Install Campaign Identification Label.
Campaign ID Label & Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Each "Campaign Identification Label", is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
"Campaign Identification Labels" can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean, dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Accelerator
Controls: > 95C23 > Jun > 95 > Recall - Excessive Friction in Accelerator Pedal > Page 4960
Net price plus 40% of all parts required for the repair.
Refer to the Chevrolet Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1994-95 Chevrolet Caprice and Impala model vehicles
may have been built with a defective accelerator pedal assembly which causes the vehicles to fail
to conform to the requirements of the Federal Motor Vehicle Safety Standard (FMVSS) 124
"Accelerator Control Systems". Under some circumstances at low temperatures, there may be
excessive friction in the accelerator pedal assembly. If there is excessive friction in the pedal
assembly, in the event of a failure of a throttle return spring the engine speed may not return to idle
as specified in FMVSS 124.
WHAT WE WILL DO
To correct this condition, it is necessary to install a new accelerator pedal assembly. This service
will be performed for you at no charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date and so the
dealer may order the necessary parts for the repair. Instructions for making this correction have
been sent to your dealer. The labor time necessary to perform this service correction is
approximately 20 minutes. Please ask your dealer if you wish to know how much additional time
will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the Administrator, National Traffic Safety Administration, 400 Seventh Street,
S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your safety and continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Page 4961
Accelerator Controls: Description and Operation
The accelerator control system is cable type. There are no linkage adjustments. Therefore, the
specific cable must be used.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Accelerator Controls <-->
[Accelerator Pedal] > Component Information > Technical Service Bulletins > Page 4962
Accelerator Controls: Service and Repair
Accelerator Pedal
REMOVE OR DISCONNECT
1. Accelerator pedal push on nut. 2. accelerator pedal from accelerator pedal lever.
INSTALL OR CONNECT
1. accelerator pedal and spring to accelerator pedal lever. 2. New push on nut to accelerator pedal
lever.
INSPECT
^ Check for complete throttle opening and closing positions by operating accelerator pedal. Also
check for poor carpet fit under the accelerator pedal. Throttle should operate freely without blind
between full closed and wide open throttle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air
Cleaner Fresh Air Duct/Hose > Component Information > Locations
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Customer Interest for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Customer Interest for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 4975
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Air Filter Element: >
04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 4981
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Page 4982
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Page 4983
Air Filter Element: Service and Repair
Air Ducting
Air Intake System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Cleaner Housing > Air Filter
Element > Component Information > Technical Service Bulletins > Page 4984
REMOVE OR DISCONNECT
1. Loosen wing nuts at front of air cleaner housing. 2. Lift air cleaner lid, Mass Air Flow (MAF)
sensor and resonator as a unit. 3. Remove air filter element.
INSTALL OR CONNECT
1. Install air filter element. 2. Move air cleaner lid, MAF sensor and resonator into place. 3. Tighten
wing nuts. 4. Check clamps at MAF sensor and tighten if necessary. 5. Check joints between duct,
resonators and throttle body for possible air leaks. Repair if necessary.
NOTICE: If the Mass Air Flow (MAF) sensor is installed backwards, the system will go rich. An
arrow cast into the plastic portion of the sensor indicates proper air flow direction. The arrow must
point toward the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Locations > Component Locations
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Locations > Component Locations > Page 4989
Powertrain Control Module (PCM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4992
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4993
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 4994
Fig.1-Symbols (Part 1 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4995
Fig.2-Symbols (Part 2 Of 3)
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Component Information > Diagrams > Diagram Information and Instructions > Page 4996
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 4997
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 4998
Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5013
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Component Information > Diagrams > Diagram Information and Instructions > Page 5014
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 5015
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Component Information > Diagrams > Diagram Information and Instructions > Page 5016
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 5017
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5018
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5019
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Component Information > Diagrams > Diagram Information and Instructions > Page 5020
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5021
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5022
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5023
MAF Sensor Circuit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Air Flow Meter/Sensor >
Component Information > Diagrams > Page 5024
Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Page 5025
Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Diagnostic Connector - Fuel
Pump > Component Information > Locations
Diagnostic Connector - Fuel Pump: Locations
The fuel pump test connector is located in the engine compartment near the A/C accumulator.
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel > Component Information
> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada)
Fuel: Technical Service Bulletins Fuel System - TOP TIER Detergent Gasoline (Canada)
INFORMATION
Bulletin No.: 05-06-04-022G
Date: October 27, 2010
Subject: TOP TIER Detergent Gasoline Information and Available Brands (Deposits, Fuel
Economy, No Start, Power, Performance, Stall Concerns) - Canada ONLY
Models:
2011 and Prior GM Passenger Cars and Trucks (Canada Only)
Supercede: This bulletin is being revised to update the model years and include an additional
gasoline brand as a TOP TIER source. Please discard Corporate Bulletin Number 05-06-04-022F
(Section 06 - Engine/Propulsion System). In the U.S., refer to the latest version of Corporate
Bulletin Number 04-06-04-047I.
A new class of fuel called TOP TIER Detergent Gasoline is appearing at retail stations of some fuel
marketers. This gasoline meets detergency standards developed by six automotive companies. All
vehicles will benefit from using TOP TIER Detergent Gasoline over gasoline containing the "Lowest
Additive Concentration" recommended by the Canadian General Standards Board (CGSB). Those
vehicles that have experienced deposit related concerns may especially benefit from use of TOP
TIER Detergent Gasoline.
Intake valve: 16,093 km (10,000 mi) with TOP TIER Detergent Gasoline
Intake valve: 16,093 km (10,000 mi) with Minimum Additive recommended by the CGSB
Top Tier Fuel Availability
Chevron was the first to offer TOP TIER Detergent Gasoline in Canada. Shell became the first
national gasoline retailer to offer TOP TIER Detergent Gasoline across Canada. Petro-Canada
began offering TOP TIER Detergent Gasoline nationally as of October 1, 2006. Sunoco began
offering TOP TIER Detergent Gasoline in March of 2007. Esso began offering TOP TIER Detergent
Gasoline in May of 2010.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel > Component Information
> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada) > Page 5033
Gasoline Brands That Currently Meet TOP TIER Detergent Gasoline Standards
The following gasoline brands meet the TOP TIER Detergent Gasoline Standards in all octane
grades :
Chevron Canada (markets in British Columbia and western Alberta)
- Shell Canada (nationally)
- Petro-Canada (nationally)
- Sunoco-Canada (Ontario)
- Esso-Canada (nationally)
What is TOP TIER Detergent Gasoline?
TOP TIER Detergent Gasoline is a new class of gasoline with enhanced detergency and no
metallic additives. It meets new, voluntary deposit control standards developed by six automotive
companies that exceed the detergent recommendations of Canadian standards and does not
contain metallic additives, which can damage vehicle emission control components.
Where Can TOP TIER Detergent Gasoline Be Purchased?
The TOP TIER program began in the U.S. and Canada on May 3, 2004. Some fuel marketers have
already joined and introduced TOP TIER Detergent Gasoline. This is a voluntary program and not
all fuel marketers will offer this product. Once fuel marketers make public announcements, they will
appear on a list of brands that meet the TOP TIER standards.
Who developed TOP TIER Detergent Gasoline standards?
TOP TIER Detergent Gasoline standards were developed by six automotive companies: BMW,
General Motors, Honda, Toyota, Volkswagen and Audi.
Why was TOP TIER Detergent Gasoline developed?
TOP TIER Detergent Gasoline was developed to increase the level of detergent additive in
gasoline. In the U.S., government regulations require that all gasoline sold in the U.S. contain a
detergent additive. However, the requirement is minimal and in many cases, is not sufficient to
keep engines clean. In Canada, gasoline standards recommend adherence to U.S. detergency
requirements but do not require it. In fact, many brands of gasoline in Canada do not contain any
detergent additive. In order to meet TOP TIER Detergent Gasoline standards, a higher level of
detergent is needed than what is required or recommended, and no metallic additives are allowed.
Also, TOP TIER was developed to give fuel marketers the opportunity to differentiate their product.
Why did the six automotive companies join together to develop TOP TIER?
All six corporations recognized the benefits to both the vehicle and the consumer. Also, joining
together emphasized that low detergency and the intentional addition of metallic additives is an
issue of concern to several automotive companies.
What are the benefits of TOP TIER Detergent Gasoline?
TOP TIER Detergent Gasoline will help keep engines cleaner than gasoline containing the "Lowest
Additive Concentration" recommended by Canadian standards. Clean engines help provide optimal
fuel economy and engine performance, and also provide reduced emissions. Also, the use of TOP
TIER Detergent Gasoline will help reduce deposit related concerns.
Who should use TOP TIER Detergent Gasoline?
All vehicles will benefit from using TOP TIER Detergent Gasoline over gasoline containing the
"Lowest Additive Concentration" recommended by Canadian standards. Those vehicles that have
experienced deposit related concerns may especially benefit from use of TOP TIER Detergent
Gasoline. More information on TOP TIER Detergent Gasoline can be found at this website,
http://www.toptiergas.com/.
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> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada) > Page 5034
Disclaimer
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel > Component Information
> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada) > Page 5035
Fuel: Technical Service Bulletins Fuel System - 'TOP TIER' Detergent Gasoline Information
INFORMATION
Bulletin No.: 04-06-04-047I
Date: August 17, 2009
Subject: TOP TIER Detergent Gasoline (Deposits, Fuel Economy, No Start, Power, Performance,
Stall Concerns) - U.S. Only
Models:
2010 and Prior GM Passenger Cars and Trucks (including Saturn) (U.S. Only) 2003-2010
HUMMER H2 (U.S. Only) 2006-2010 HUMMER H3 (U.S. Only) 2005-2009 Saab 9-7X (U.S. Only)
Supercede: This bulletin is being revised to add model years and additional sources to the Top Tier
Fuel Retailers list. Please discard Corporate Bulletin Number 04-06-04-047H (Section 06 Engine/Propulsion System). In Canada, refer to Corporate Bulletin Number 05-06-04-022F.
A new class of fuel called TOP TIER Detergent Gasoline is appearing at retail stations of some fuel
marketers. This gasoline meets detergency standards developed by six automotive companies. All
vehicles will benefit from using TOP TIER Detergent Gasoline over gasoline containing the "Lowest
Additive Concentration" set by the EPA. Those vehicles that have experienced deposit related
concerns may especially benefit from the use of TOP TIER Detergent Gasoline.
Intake valve: - 10,000 miles with TOP TIER Detergent Gasoline
Intake valve: - 10,000 miles with Legal Minimum additive
Gasoline Brands That Currently Meet TOP TIER Detergent Gasoline Standards
As of August 1, 2009, all grades of the following gasoline brands meet the TOP TIER Detergent
Gasoline Standards:
- Chevron
- Chevron-Canada
- QuikTrip
- Conoco
Phillips 66
- 76
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> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada) > Page 5036
- Shell
- Shell-Canada
- Entec Stations located in the greater Montgomery, Alabama area.
- MFA Oil Company located throughout Missouri.
- Kwik Trip, Inc. in Minnesota and Wisconsin and Kwik Star convenience stores in Iowa.
The Somerset Refinery, Inc. at Somerset Oil stations in Kentucky.
Aloha Petroleum
- Tri-Par Oil Company
- Turkey Hill Minit Markets
- Texaco
- Petro-Canada
- Sunoco-Canada
- Road Ranger located in Illinois, Indiana, Iowa, Kentucky, Missouri, Ohio and Wisconsin
What is TOP TIER Detergent Gasoline?
TOP TIER Detergent Gasoline is a new class of gasoline with enhanced detergency. It meets new,
voluntary deposit control standards developed by six automotive companies that exceed the
detergent requirements imposed by the EPA.
Where Can TOP TIER Detergent Gasoline Be Purchased?
The TOP TIER program began on May 3, 2004 and many fuel marketers have joined the program
and have introduced TOP TIER Detergent Gasoline. This is a voluntary program and not all fuel
marketers will offer this product. Once fuel marketers make public announcements, they will appear
on a list of brands that meet the TOP TIER standards.
Where Can I find the Latest Information on TOP TIER Fuel and Retailers?
On the web, please visit www.toptiergas.com for additional information and updated retailer lists.
Who developed TOP TIER Detergent Gasoline standards?
TOP TIER Detergent Gasoline standards were developed by six automotive companies: Audi,
BMW, General Motors, Honda, Toyota and Volkswagen.
Why was TOP TIER Detergent Gasoline developed?
TOP TIER Detergent Gasoline was developed to increase the level of detergent additive in
gasoline. The EPA requires that all gasoline sold in the U.S. contain a detergent additive. However,
the requirement is minimal and in many cases, is not sufficient to keep engines clean. In order to
meet TOP TIER Detergent Gasoline standards, a higher level of detergent is needed than what is
required by the EPA. Also, TOP TIER was developed to give fuel marketers the opportunity to
differentiate their product.
Why did the six automotive companies join together to develop TOP TIER?
All six corporations recognized the benefits to both the vehicle and the consumer. Also, joining
together emphasized that low detergency is an issue of concern to several automotive companies.
What are the benefits of TOP TIER Detergent Gasoline?
TOP TIER Detergent Gasoline will help keep engines cleaner than gasoline containing the "Lowest
Additive Concentration" set by the EPA. Clean engines help provide optimal fuel economy and
performance and reduced emissions. Also, use of TOP TIER Detergent Gasoline will help reduce
deposit related concerns.
Disclaimer
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel > Component Information
> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada) > Page 5037
Fuel: Technical Service Bulletins Fuel - Top Tier Detergent Gasoline Information
Bulletin No.: 04-06-00-047
Date: June 24, 2004
ADVANCED SERVICE INFORMATION
Subject: Top Tier Detergent Gasoline (Deposits, Fuel Economy, No Start, Power, Performance,
Stall Concerns)
Models: 2005 and Prior All General Motors Passenger Cars and Trucks (U.S. Only)
A new class of gasoline, called Top Tier Detergent Gasoline, will be appearing at retail stations of
some fuel marketers. This gasoline meets detergency standards developed by four automotive
companies. A description of the concept and benefits of Top Tier is provided in the following
question and answer section.
What is Top Tier Detergent Gasoline?
Top Tier Detergent Gasoline is a new class of gasoline with enhanced detergency. It meets new,
voluntary deposit control standards developed by four automotive companies that exceed the
detergent requirements imposed by the EPA.
Who developed Top Tier Detergent Gasoline standards?
Top Tier Detergent Gasoline standards were developed by four automotive companies: BMW,
General Motors, Honda and Toyota.
Why was Top Tier Detergent Gasoline developed?
Top Tier Detergent Gasoline was developed to increase the level of detergent additive in gasoline.
The EPA requires that all gasoline sold in the U.S. contain a detergent additive. However, the
requirement is minimal and in many cases, is not sufficient to keep engines clean. In order to meet
Top Tier Detergent Gasoline standards, a higher level of detergent is needed than what is required
by the EPA. Also, Top Tier was developed to give fuel marketers the opportunity to differentiate
their product.
Why did the four automotive companies join together to develop Top Tier?
All four corporations recognized the benefits to both the vehicle and the consumer. Also, joining
together emphasized that low detergency is an issue of concern to several automotive companies.
What are the benefits of Top Tier Detergent Gasoline?
Top Tier Detergent Gasoline will help keep engines cleaner than gasoline containing the "Lowest
Additive Concentration" set by the EPA. Clean engines help provide optimal fuel economy and
performance and reduced emissions. Also, use of Top Tier Detergent Gasoline will help reduce
deposit related concerns.
Who should use Top Tier Detergent Gasoline?
All vehicles will benefit from using Top Tier Detergent Gasoline over gasoline containing the
"Lowest Additive Concentration" set by the EPA. Those vehicles that have experienced deposit
related concerns may especially benefit from use of Top Tier Detergent Gasoline.
Where can Top Tier Detergent Gasoline be purchased?
The Top Tier program began on May 3, 2004. Some fuel marketers have already joined and are
making plans to introduce Top Tier Detergent Gasoline. This is a voluntary program and not all fuel
marketers will offer this product. Once fuel marketers make public announcements, a list of all fuel
marketers meeting Top Tier standards will be made available. For now, look for the "Top Tier"
designation at the gas pump.
Disclaimer
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> Technical Service Bulletins > Fuel System - TOP TIER Detergent Gasoline (Canada) > Page 5038
Fuel: Technical Service Bulletins Fuel - Reformulated/Oxygenated Gasolines
FILE IN SECTION: 0 - General Information
BULLETIN NO.: 57-01-02
DATE: June, 1995
SUBJECT: Reformulated Gasoline (RFG), Oxygenated Gasoline and California Phase 2 RFG
MODELS: 1995 and Prior Passenger Cars and Trucks
General Motors customers will be potentially exposed to a variety of different fuel types. Besides
the conventional gasoline available, new types such as Reformulated Gasoline (RFG), oxygenated
gasoline, and starting in 1996, California Phase 2 RFG. Reformulated Gasoline (RFG) is blended
to burn more cleanly and not to evaporate as readily. RFG must contain a minimum of 2 percent
oxygen, which is usually achieved with ethanol or EPA-approved ethers such as methyl
tertiary-butyl ether (MTBE). This type of fuel is required by the Clean Air Act in the nine worst
ozone non-attainment areas of the country, and may also be required in other areas designated
ozone non-attainment, at the option of the states. RFG is intended to produce approximately 15
percent less pollution than conventional gasoline. Using RFG should reduce the total health risk to
the public by reducing exposure to ozone and air toxins. General Motors supports the use of RFG
as a cost effective means of providing air quality benefits.
Oxygenated gasolines are prevalent in the wintertime for Carbon Monoxide (CO) non-attainment
areas. These fuels contain oxygen components similar to RFG. Approximately 50 percent of the
fuel sold in the U.S. in the wintertime contains an oxygenate component.
Vehicle fuel economy may be slightly reduced, if at all, by the use of gasoline containing
oxygenates. Fuel economy is most affected by engine and vehicle type, driving habits, weather
conditions, and vehicle maintenance.
Properly blended RFG, oxygenated gasoline, and California Phase 2 RFG will have no adverse
effect on vehicle performance or to the durability of engine and fuel system components. In fact,
the General Motors Owner's Manual fuel statements have consistently permitted the use of
properly blended fuels containing up to 10 percent ethanol (since 1980) and up to 15 percent
methyl tertiary-butyl ether (MTBE) for current and all past model year vehicles. These statements
continue to be valid. The use of oxygenate-containing fuels will not invalidate the GM vehicle
warranty.
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> Technical Service Bulletins > Page 5039
Fuel: Specifications
FUEL SPECIFICATIONS
The fuel must meet ASTM Standard: D4814 (U.S.).
OCTANE REQUIREMENTS
Minimum octane recommended: 87 {(R+M)/2} octane where R = research octane number and M =
motor octane number.
GASOLINE WITH ALCOHOL
NOTICE: Do not spill fuel containing alcohol on the vehicle. Alcohol can cause damage to the paint
finish and trim.
Methyl Tertiary-Butyl Ether (MTBE) Fuel containing Methyl Tertiary-butyl Ether (MTBE) may be
used, providing there is no more than 15% alcohol by volume.
Ethanol Fuel containing ethanol (ethyl) or grain alcohol may be used, providing there is no more
than 10% ethanol alcohol by volume.
Methanol Fuel containing methanol (methyl) or wood alcohol may be used, providing there is no
more than 5% methanol by volume. Use of fuel (gasohol) that contains more than 5% methanol
can corrode metal fuel system components and damage plastic and rubber parts.
NOTICE: Do not use fuel that contains more than 5% methanol. Use of a fuel (gasohol) that
contains more than 5% of methanol can corrode metal fuel system components and damage
plastic and rubber parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Filler Cap > Component
Information > Locations
Filler Pipe And Cap
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Filler Cap > Component
Information > Locations > Page 5043
Fuel Filler Cap: Description and Operation
Filler Pipe And Cap
The fuel tank filler pipe is equipped with a threaded-type cap. The threaded part of the cap requires
several turns counterclockwise to remove. A built-in torque-limiting device prevents over tightening.
To install, turn the cap clockwise until a clicking noise is heard. This signals that the correct torque
has been reached and the cap is fully seated.
NOTICE: If a fuel filler cap requires replacement, use only a cap with the same features. Failure to
use the correct cap can result in a serious malfunction of the system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Filter > Fuel Pressure
Release > System Information > Service and Repair
Fuel Pressure Release: Service and Repair
WARNING:
- To reduce the risk of fire and personal injury, it is necessary to relieve the fuel system pressure
before servicing fuel system components.
- After relieving the fuel system pressure a small amount of fuel may be released when servicing
fuel lines or connections. In order to reduce the chance of personal injury, cover fuel line fittings
with a shop towel before disconnecting, to catch any fuel that may leak out. Place the shop towel in
an approved container when the disconnect is complete.
Fuel Pressure Test Port
PROCEDURE:
1. Disconnect the negative battery cable to avoid possible fuel discharge if an accidental attempt is
made to start the engine. 2. Loosen the fuel filler cap to relieve tank pressure. 3. Connect the J
34730-1 fuel pressure gauge to the fuel pressure connection on the fuel rail. Wrap a shop towel
around the fitting while connecting
the gauge to avoid spillage.
4. Install a bleed hose into an approved container and open the valve slowly to relieve system
pressure. Fuel connections are now safe for servicing. 5. Drain any fuel remaining in the gauge into
an approved container.
NOTE: After repairs are complete, tighten the fuel cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Technical Service Bulletins > Fuel System - Fuel Injector Maintenance Cleaning
Fuel Injector: Technical Service Bulletins Fuel System - Fuel Injector Maintenance Cleaning
Bulletin No.: 04-06-04-051B
Date: January 04, 2006
INFORMATION
Subject: Maintenance Cleaning of Fuel Injectors
Models: 2006 and Prior All General Motors Passenger Cars and Trucks 2003-2006 HUMMER H2
2006 HUMMER H3
Supercede:
This bulletin is being revised to add models and model years and update the name and part
number of GM Fuel System Treatment. Please discard Corporate Bulletin Number 04-06-04-051A
(Section 06 - Engine/Propulsion System).
General Motors is aware that some companies are marketing tools, equipment and programs to
support fuel injector cleaning as a preventative maintenance procedure. General Motors does not
endorse, support or acknowledge the need for fuel injector cleaning as a preventative maintenance
procedure. Fuel injector cleaning is approved only when performed as directed by a published GM
driveability or DTC diagnostic service procedure.
Due to variation in fuel quality in different areas of the country, the only preventative maintenance
currently endorsed by GM regarding its gasoline engine fuel systems is the addition of GM Fuel
System Treatment PLUS, P/N 88861011 (for U.S. ACDelco(R), use P/N 88861013) (in Canada,
P/N 88861012), added to a tank of fuel at each oil change. Refer to Corporate Bulletin Number
03-06-04-030A for proper cleaning instructions.
Disclaimer
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Fuel Injector: Technical Service Bulletins Tools - Introduction Of The Fuel Injector Tester
NO.: 93-I-39 DATE: June, 1993 GROUP: 6 CORP. NO.: 316501R
SUBJECT: INFORMATION ON THE INTRODUCTION OF THE FUEL INJECTOR TESTER TOOL
J - 39021
This bulletin is being revised to add information about the coil test and a list of driveability
problems.
In February, 1993, Kent-Moore shipped a new Fuel Injector Tester, tool J-39021, as part of the
Essential Tool Program. This tool has the capability of performing injector balance and coil tests on
all GM and many non-GM fuel injection systems. The injector balance test is one familiar to most
technicians where fuel pressure drop is measured as an injector is energized for a set period of
time. This fuel pressure drop is compared to that of the other injectors in the vehicle or a published
standard.
The injector coil test is a new test whereby the injector's resistance is measured during normal
gperation by feeding a fixed current through the injector and measuring the voltage across the
injector. Injector coil failures are more accurately detected using this method than by simply
measuring the injectors resistance with an ohmmeter. Refer to the instructions included with the
tool for testing procedures.
This tool, and the injector coil test specifically, were developed to detect deterioration of injector
coils due to the introduction of injector cleaners and fuel blends containing high levels of alcohol.
Alcohol and water carried by the alcohol may attack and corrode injector coils resulting in a change
in coil resistance and one or more of the following driveability symptoms:
^ rough idle
^ engine miss/surge
^ stall after start/hard start
^ fails emission test
^ poor fuel economy
^ exhaust odor
The injector coil test procedure also requires the use of the Digital Voltmeter, J-39200, to measure
the voltage across the injector during the test. The Fuel Injector Tester, J-39021, supplies one of
three fixed current values throughout the duration of the test. Selection of the supply current value
(0.5, 2.5, or 4.0 amps) is based on the injector's specified resistance. When the push-to-start-test
button is pressed, the tool energizes the injector coil for five seconds. The condition of the injector
coil (pass/fail) is determined by the voltage reading displayed on the voltmeter while the injector is
energized. Instructions and specifications for most GM fuel injectors are included with the tool.
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Information > Technical Service Bulletins > Page 5053
Fuel Injector: Specifications
Injector Resistence ..............................................................................................................................
........................................................ 11.8 - 12.6 ohms
At 68 degrees F
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Information > Technical Service Bulletins > Page 5054
Fuel Injector: Locations
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Technical Service Bulletins > Page 5055
Engine Left Side Upper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Diagram Information and Instructions
Fuel Injector: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Information > Diagrams > Diagram Information and Instructions > Page 5058
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Information > Diagrams > Diagram Information and Instructions > Page 5059
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information > Diagrams > Diagram Information and Instructions > Page 5060
Fig.1-Symbols (Part 1 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Diagram Information and Instructions > Page 5061
Fig.2-Symbols (Part 2 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Diagram Information and Instructions > Page 5062
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Information > Diagrams > Diagram Information and Instructions > Page 5063
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 5064
Fuel Injector: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 5065
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Information > Diagrams > Diagram Information and Instructions > Page 5066
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Information > Diagrams > Diagram Information and Instructions > Page 5081
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Information > Diagrams > Diagram Information and Instructions > Page 5082
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 5083
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Diagram Information and Instructions > Page 5084
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Diagram Information and Instructions > Page 5085
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information > Diagrams > Diagram Information and Instructions > Page 5086
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 5087
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information > Diagrams > Diagram Information and Instructions > Page 5088
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Page 5089
Fuel Injector: Application and ID
Fuel Injector Id
When ordering new fuel injectors, be sure to order the correct injector for the application being
serviced. The upper and lower fuel injector O-rings use different part numbers. To identify the
correct 0-ring, the upper 0-ring is black and the lower 0-ring is brown. Both are the same size but
are made of different material.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Page 5090
Fuel Injector: Description and Operation
Fuel Injector
The top-feed fuel injector assembly is a solenoid operated device, controlled by the Powertrain
Control Module (PCM), that meters pressurized fuel to a single engine cylinder. The PCM
energizes the injector solenoid. which opens a ball valve, allowing fuel to flow past the ball valve,
and through a recessed flow director plate. The director plate has six machined holes that control
the fuel flow, generating a conical spray pattern of finely atomized fuel at the injector tip.
Fuel is directed at the intake valve, causing it to become further atomized and vaporized before
entering the combustion chamber.
An injector that is stuck partly open would cause loss of pressure after engine shutdown.
Consequently, long cranking times would be noticed on some engines. Dieseling could also occur,
because some fuel could be delivered to the engine after the ignition is turned "OFF".
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Page 5091
Fuel Injector: Testing and Inspection
Most GM manufacturers now use a voltage drop and/or a fuel pressure drop test to measure Fuel
Injector Coil Integrity.
These test sequences can be found in Computers and Control Systems, under A, C or System
Diagnostic Charts. See: Computers and Control Systems/Testing and Inspection
Within these tests you might find an "Ohm" reading of the Injector, but generally this measurement
is No Longer Used to solely determine the Pass/Fail quality of the Injector coil.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Injector > Component
Information > Diagrams > Page 5092
Fuel Injector: Service and Repair
Fuel Injector and Clip
CAUTION: Use care in removing the fuel injectors to prevent damage to the electrical connector
pins on the injector and the nozzle. The fuel injector is serviced as a complete assembly only. The
fuel injector is an electrical component and should not be immersed in any type of cleaner. If fuel
injectors are found to be leaking, the engine oil may be contaminated with fuel.
REMOVE OR DISCONNECT
1. Disconnect negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery / Service and Repair.
3. Remove Fuel Rail assembly.
^ Refer to Fuel Rail / Service and Repair.
DISASSEMBLE
1. Spread injector clip to release injector from fuel rail. 2. Fuel injector assembly. 3. Discard injector
retainer clip. 3. Injector O-ring seals from both ends of injector and discard. Save O-Ring backup
for use in reinstallation.
NOTICE: ^
Refer to Application and ID to insure ordering correct replacement parts.
^ When replacing injector 0-rings, be sure to install the brown 0-ring in the lower position.
^ The fuel injector lower O-ring uses a nylon collar, called the O-ring backup, to properly position
the O-ring on the injector. Be sure to reinstall the O-ring backup, or the sealing O-ring may move
on the injector when installing the fuel rail and result in a possible vacuum leak.
ASSEMBLE
1. Lubricate new injector O-ring seals with clean engine oil, and install on injector. 2. New retainer
clip onto injector. 3. Fit injector into fuel rail injector socket, with electrical connector facing outward.
4. Push injector into socket until retainer clip locks onto flange on fuel rail.
INSTALL OR CONNECT
1. Install fuel rail assembly. 2. Tighten fuel filler cap 3. Connect negative battery cable
INSPECT
^ Turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Regulator >
Component Information > Specifications
Fuel Pressure Regulator: Specifications
Fuel Pressure Regulator Attaching Screw
................................................................................................................................................... 10
Nm (89 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Regulator >
Component Information > Specifications > Page 5096
Fuel Pressure Regulator: Locations
Fuel Rail Assembly.
The fuel pressure regulator is bolted to the fuel rail assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Regulator >
Component Information > Specifications > Page 5097
Fuel Pressure Regulator: Description and Operation
Pressure Regulator
The fuel pressure regulator is a diaphragm-operated relief valve with fuel pump pressure on one
side, and regulator spring pressure and intake manifold vacuum on the other. The regulator's
function is to maintain a constant pressure differential across the injectors at all times. The
pressure regulator compensates for engine load by increasing fuel pressure as engine vacuum
drops.
With the ignition "ON" and engine "OFF" (zero vacuum), system fuel pressure at the pressure test
connection should be 284 - 325 kPa (41 - 47 psi). If the pressure is too low, poor performance
could result. If the pressure is too high excessive odor and a Diagnostic Trouble Code (DTC) 45/65
may result. CHART A-7 has information on diagnosing fuel pressure conditions.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Regulator >
Component Information > Specifications > Page 5098
Fuel Pressure Regulator: Service and Repair
Fuel Rail Assembly.
Fuel Pressure Regulator Assembly.
NOTICE: Fuel pressure Regulator is serviced as a complete assembly only.
REMOVE OR DISCONNECT
1. Disconnect negative battery terminal. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery / Service and Repair.
3. Remove fuel rail assembly.
^ Refer to Fuel Rail / Service and Repair.
DISASSEMBLE
1. Remove fuel tube bracket attaching screw and bracket. 2. Remove pressure regulator attaching
screw.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Regulator >
Component Information > Specifications > Page 5099
3. Remove pressure regulator from fuel rail. 4. Remove fuel outlet tube retainer clip and fuel outlet
tube from pressure regulator. 6. Remove fuel regulator inlet O-ring and discard. 6. Remove fuel
outlet tube O-ring and discard.
INSPECT
^ Filter screen for contamination. Remove and discard if dirty.
ASSEMBLE
1. Lubricate new pressure regulator inlet O-ring with clean engine oil and install on regulator. 2.
Lubricate new fuel outlet tube O-ring with clean engine oil and install on on fuel outlet tube. 3.
Install fuel outlet tube into regulator and install retainer clip. 4. Push regulator into rail 5. Pressure
regulator attaching screw.
Thread-Locking Material The hardware used to attach the pressure regulator is coated with
thread-locking adhesive. If the pressure regulator are removed for service, inspect the attaching
screw threads. There should he enough thread-locking material (adhesive or compound) on the
threads to insure proper relocking. If not, clean the threads and apply Loctite 262 to the threads
before re-assembly Replacement screws are included in the service screw assortment package.
New attaching hardware is included in the service packages.
Tighten ^
Pressure regulator attaching screw to 10 Nm (89 lb in.).
6. Fuel tube bracket and attaching screw.
Tighten ^
Pressure regulator attaching screw to 5 Nm (44 lb in.).
INSTALL OR CONNECT
1. Fuel rail assembly. 2. Tighten fuel filler cap. 3. Connect negative battery cable.
INSPECT
^ Turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Test Port >
Component Information > Locations
Fuel Pressure Test Port
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pressure Test Port >
Component Information > Locations > Page 5103
Fuel Pressure Test Port: Service and Repair
Fuel Test Port Valve
CLEAN
^ Area around fuel pressure connection with GM X-3OA or equivalent.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery System / Service and Repair.
3. Fuel pressure connection valve assembly.
INSTALL OR CONNECT
1. Fuel pressure connection valve assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten
seconds. Again turn to "ON" position, and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pump > Fuel Pressure >
Diagnostic Connector - Fuel Pump > Component Information > Locations
Diagnostic Connector - Fuel Pump: Locations
The fuel pump test connector is located in the engine compartment near the A/C accumulator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Fuel Pressure Test Port > Component Information > Locations
Fuel Pressure Test Port
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pump > Fuel Pressure >
Fuel Pressure Test Port > Component Information > Locations > Page 5112
Fuel Pressure Test Port: Service and Repair
Fuel Test Port Valve
CLEAN
^ Area around fuel pressure connection with GM X-3OA or equivalent.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to Fuel Delivery System / Service and Repair.
3. Fuel pressure connection valve assembly.
INSTALL OR CONNECT
1. Fuel pressure connection valve assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten
seconds. Again turn to "ON" position, and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Pump > Fuel Pump Relay
> Component Information > Locations
Fuel Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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> Component Information > Diagrams > Diagram Information and Instructions
Fuel Pump Relay: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5118
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5119
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5120
Fig.1-Symbols (Part 1 Of 3)
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5121
Fig.2-Symbols (Part 2 Of 3)
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5122
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5123
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Fuel Pump Relay: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5141
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5143
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5144
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5145
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5146
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5147
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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> Component Information > Diagrams > Diagram Information and Instructions > Page 5148
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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> Component Information > Diagrams > Page 5149
Fuel Pump Relay: Description and Operation
When the ignition switch is turned to the "ON" position (before engaging starter), the energizes the
fuel pump relay for two seconds causing the fuel pump to pressurize the fuel system. If the
Powertrain Control Module (PCM) does not receive ignition reference pulses (engine cranking or
running) within two seconds, it shuts "OFF" the fuel pump relay, causing the fuel pump to stop.
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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> Component Information > Diagrams > Page 5150
Fuel Pump Relay: Service and Repair
Fuel Pump (Circuit Opening) Relay
REMOVE OR DISCONNECT
1. Underhood (U/H) electrical center cover. 2. Fuel pump relay.
INSTALL OR CONNECT
1. Fuel pump relay. 2. Underhood (U/H) electrical center cover.
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Information > Specifications
Fuel Rail: Specifications
Fuel Crossover Tube Screws ..............................................................................................................
........................................................... 5 Nm (44 lb in.)
Fuel Pressure Regulator Screw ...........................................................................................................
......................................................... 10 Nm (89 lb in.)
Fuel Rail and Resonator Bracket Bolts
........................................................................................................................................................ 10
Nm (89 lb in.)
Fuel Tube Bracket Attaching Screw
..............................................................................................................................................................
5 Nm (44 lb in.)
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Fuel Rail
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Fuel Rail
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Fuel Rail: Application and ID
Fuel Rail Identification
An eight digit identification number is stamped on the fuel rail assembly. Refer to this model
identification number if servicing or part replacement is required. Names of component parts will be
found on the numbered list that accompanies the disassembled view in Fuel Rail / Diagrams.
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Fuel Rail: Description and Operation
Fuel Rail
The fuel rail assembly is mounted to the engine intake manifold and performs several functions; it
positions the injectors in the intake manifold, it distributes fuel evenly to the injectors, and it
integrates the fuel pressure regulator into the fuel metering system.
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Fuel Rail: Service and Repair Fuel Rail X-Over Tube
Fuel X-Over Tube
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to the Fuel Delivery System / Service and Repair.
3. Fuel rail assembly.
^ Refer to Fuel Rail / Service and Repair.
DISASSEMBLE
1. Fuel tube bracket attaching screw and bracket. 2. Crossover tube retainer attaching screws. 3.
Crossover tube assembly from fuel rails. 4. 0-rings from crossover tube assembly and discard.
ASSEMBLE
1. Lubricate new crossover tube assembly 0-rings with clean engine oil and install on crossover
tube. 2. Crossover tube assembly into fuel rail sections. 3. Crossover tube retainer attaching
screws.
Tighten ^
Crossover tube retainer attaching screws to 5 Nm (44 lb in.).
4. Fuel tube bracket and attaching screw.
Tighten ^
Fuel tube bracket attaching screw to 5 Nm (44 lb in.).
INSTALL OR CONNECT
1. Fuel rail assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
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Fuel Rail: Service and Repair Fuel Outlet Tube
Fuel Outlet Tube
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to the Fuel Delivery System / Service and Repair.
3. Fuel rail assembly.
^ Refer to Fuel Rail / Service and Repair.
DISASSEMBLE
1. Fuel tube bracket and attaching screw. 2. Fuel outlet tube retainer clip. 3. Fuel outlet tube from
pressure regulator. 4. 0-ring from outlet tube and discard.
ASSEMBLE
1. Lubricate new 0-ring with clean engine oil and install on fuel outlet tube. 2. Push fuel outlet tube
into fuel pressure regulator. 3. Fuel outlet tube retainer clip. 4. Fuel tube bracket and attaching
screw.
Tighten ^
Fuel tube bracket attaching screw to 5 Nm (44 lb in.).
INSTALL OR CONNECT
1. Fuel rail assembly. 2. Tighten fuel filler cap. 3. Negative battery cable.
INSPECT
^ Turn ignition switch to "0N" position for two seconds, then turn "OFF" for ten seconds. Again turn
to "ON" position and check for fuel leaks.
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Fuel Rail: Service and Repair Fuel Rail Replacement
NOTICE
^ Use care in removing the fuel rail assembly to prevent damage to the injector electrical connector
terminals and the injector spray tips. When removed, support the rail to avoid damaging its
components.
^ Prevent dirt and other contaminates from entering open lines and passages. Fittings should be
capped, and holes plugged, during servicing.
^ The upper and lower 0-rings are different colors (black and brown). Be sure to install the black
0-ring in the upper position and the brown 0-ring in the lower position on the injector. The 0-rings
are the same size but are made of different materials.
CLEAN
^ Before removal, the fuel rail assembly may be cleaned with a spray type engine cleaner, GM
X-30A or equivalent, following package instructions. Do Not soak fuel rails in liquid cleaning
solvent.
Fuel Rail
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Fuel Rail
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure.
^ Refer to the Fuel Delivery System / Service and Repair.
3. Resonator. 4. Quick-connect fittings at engine fuel pipes:
A. Slide rubber dust covers from quick-connect fittings at engine fuel pipes. B. Grasp both sides of
fitting. Twist female connector 1/4 turn in each direction to loosen any dirt within fining.
WARNING: Safety glasses must be worn when using compressed air, as flying dirt particles may
cause eye injury.
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C. Using compressed air, blow dirt out of fitting. D. Choose correct tool from J 37088-A tool set for
size of fitting. Insert tool into female connector, then push/pull inward to release locking tabs. E.
Pull connection apart.
CLEAN AND INSPECT
NOTICE: If it is necessary to remove rust or burrs from fuel pipe, use emery cloth in a radial motion
with the pipe end to prevent damage to O-ring sealing surface.
^ Using a clean shop towel, wipe off male pipe end.
^ Inspect both ends of fitting for dirt and burrs. Clean or replace component assemblies as
required.
5. Vacuum lines at pressure regulator and Emissions Vapor (EVAP) canister purge solenoid. 6.
Electrical harness and cables from routing clips on resonator bracket. 7. Resonator bracket. 8.
Injector electrical connectors.
^ Identify connectors to their corresponding injectors to assure correct sequential injector firing
order after reassembly.
9. Fuel rail assembly.
DISASSEMBLE
^ Injector lower 0-ring seal (Brown) from spray tip end of each injector. Discard 0-ring seals. Save
0-ring backups.
^ The fuel injector lower 0-ring uses a nylon collar, called the 0-ring backup, to properly position the
0-ring on the injector. Be sure to reinstall the 0-ring backup, or the sealing 0-ring may move on the
injector when installing the fuel rail and result in a possible vacuum leak and driveability complaints
will occur.
ASSEMBLE
^ Lubricate new lower injector 0-ring seals (brown) and install on spray tip end of each injector.
INSTALL OR CONNECT
1. Fuel rail assembly to intake manifold. 2. Resonator bracket.
Tighten ^
Fuel rail and resonator attaching bolts to 10 Nm (89 lb in.).
3. Injector electrical connectors.
^ Make sure that each connector is installed on the proper injector to assure correct sequential
injector firing order.
^ Rotate injector(s) as required to avoid stretching wire harness.
4. Electrical harness and cables into routing clips on resonator bracket. 5. Vacuum lines to EVAP
canister purge solenoid and fuel pressure regulator. 6. Quick-connect fittings to engine fuel pipes:
A. Apply a few drops of clean engine oil to the male ends of the engine fuel rail inlet and outlet
tubes.
B. Push both sides of fitting together to cause the retaining tabs/fingers to snap into place.
C. Once installed, pull on both sides of fitting to make sure connection is secure.
D. Slide dust covers over quick-connect fittings.
7. Tighten fuel filler cap. 8. Negative battery cable.
Inspect
^ Turn ignition switch to "0N" position for two seconds, then turn "OFF" for ten seconds. Again turn
to "ON" position and check for fuel leaks.
9. Resonator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Return Line > Component
Information > Locations
Fuel Return Line: Locations
Supply And Return Line Replacement
The fuel supply and return lines are routed along the left frame rail under the vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Return Line > Component
Information > Description and Operation > Nylon Fuel Pipes
Fuel Return Line: Description and Operation Nylon Fuel Pipes
Nylon fuel pipes are designed to perform the same job as the steel or flexible fuel pipes or hoses
they replace. Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to
fuel additives, and changes in temperature. There are two sizes used: 3/8" ID for the fuel feed, and
5/16" ID for the fuel return.
The fuel feed and return pipes are assembled as a harness. Retaining clips hold the pipes together
and provide a means for attaching the pipes to the vehicle. Sections of the pipes that are exposed
to chafing, high temperature or vibration are protected with heat resistant rubber hose and/or
corrugated plastic conduit.
Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle.
However, if forced into sharp bends, nylon pipes will kink and restrict fuel flow. Also, once exposed
to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far. Some special care
should be taken when working on a vehicle with nylon fuel pipes.
WARNING: To Reduce the Risk of Fire and Personal Injury:
^ Always cover nylon fuel pipes with a wet towel before using a torch near them. Also, never
expose the vehicle to temperatures higher then 115° C (239° F) for more than one hour, or more
than 90° C (194° F) for any extended period.
^ Take care not to nick or scratch the nylon fuel pipes. If damaged, they must be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Return Line > Component
Information > Description and Operation > Nylon Fuel Pipes > Page 5169
Fuel Return Line: Description and Operation Quick-Connect Fittings
Quick-connect type fittings provide a simplified means of installing and connecting fuel system
components. There are two types of quick-connect fittings used at different locations in the fuel
system. Each type consists of a unique female socket and a compatible male connector. O-rings,
located inside the female socket, provide the fuel seal. Integral locking tabs or fingers hold the
fittings together.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Return Line > Component
Information > Description and Operation > Page 5170
Fuel Return Line: Service and Repair
Supply And Return Line Replacement
TOOLS REQUIRED
J 37088-A, Fuel Line Separator Tool Set.
NOTICE:
^ If nylon fuel feed or return pipes becomes kinked, and cannot be straightened, they must be
replaced.
^ Do Not attempt to repair sections of nylon fuel pipes. If damaged, replace.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure. Refer to Fuel Delivery / Service and
Repair. 3. Quick-connect fittings at fuel rail in engine compartment. 4. Fuel feed and return pipe
retaining clip at brake booster. 5. Raise vehicle. 6. Quick-connect fittings at fuel filter. 7. Lower fuel
tank shield attaching screws and lower fuel tank shields. 8. Fuel feed, return, and EVAP pipe
underbody retainer. 9. Quick-connect fittings at fuel sender assembly.
10. Fuel feed and return pipe retaining clips and fuel feed and return pipes.
^ Note position of fuel pipes for installation.
INSTALL OR CONNECT
WARNING: To Reduce the Risk of Fire and Personal Injury:
^ If nylon fuel pipes are nicked, scratched or damaged during installation, they must be replaced.
^ When installing new fuel pipes, Do NOT hammer directly on the fuel harness body clips as this
may damage the nylon pipes resulting in a possible fuel leak.
1. Lower vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Return Line > Component
Information > Description and Operation > Page 5171
2. Rear ends of fuel feed and return pipes into top forward frame hole. 3. Raise vehicle. 4. Route
pipes in same position as noted during disassembly. 5. Quick-connect fittings at fuel sender
assembly. 6. Fuel feed, return, and EVAP pipe underbody retainer. 7. Lower fuel tank shields and
tank shield attaching screws.
Tighten Lower fuel tank shield screws to 1 Nm (9 lb in.).
8. Quick-connect fittings at fuel filter. 9. Close all retaining clips.
10. Lower vehicle. 11. Fuel feed and return pipe retaining clip at brake booster. 12. Quick-connect
fittings at fuel rail in engine compartment. 13. Negative battery cable.
INSPECT
^ Turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Supply Line > Component
Information > Locations
Fuel Supply Line: Locations
Supply And Return Line Replacement
The fuel supply and return lines are routed along the left frame rail under the vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Supply Line > Component
Information > Description and Operation > Nylon Fuel Pipes
Fuel Supply Line: Description and Operation Nylon Fuel Pipes
Nylon fuel pipes are designed to perform the same job as the steel or flexible fuel pipes or hoses
they replace. Nylon pipes are constructed to withstand maximum fuel system pressure, exposure to
fuel additives, and changes in temperature. There are two sizes used: 3/8" ID for the fuel feed, and
5/16" ID for the fuel return.
The fuel feed and return pipes are assembled as a harness. Retaining clips hold the pipes together
and provide a means for attaching the pipes to the vehicle. Sections of the pipes that are exposed
to chafing, high temperature or vibration are protected with heat resistant rubber hose and/or
corrugated plastic conduit.
Nylon fuel pipes are somewhat flexible and can be formed around gradual turns under the vehicle.
However, if forced into sharp bends, nylon pipes will kink and restrict fuel flow. Also, once exposed
to fuel, nylon pipes may become stiffer and are more likely to kink if bent too far. Some special care
should be taken when working on a vehicle with nylon fuel pipes.
WARNING: To Reduce the Risk of Fire and Personal Injury:
^ Always cover nylon fuel pipes with a wet towel before using a torch near them. Also, never
expose the vehicle to temperatures higher then 115° C (239° F) for more than one hour, or more
than 90° C (194° F) for any extended period.
^ Take care not to nick or scratch the nylon fuel pipes. If damaged, they must be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Supply Line > Component
Information > Description and Operation > Nylon Fuel Pipes > Page 5177
Fuel Supply Line: Description and Operation Quick-Connect Fittings
Quick-connect type fittings provide a simplified means of installing and connecting fuel system
components. There are two types of quick-connect fittings used at different locations in the fuel
system. Each type consists of a unique female socket and a compatible male connector. O-rings,
located inside the female socket, provide the fuel seal. Integral locking tabs or fingers hold the
fittings together.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Supply Line > Component
Information > Description and Operation > Page 5178
Fuel Supply Line: Service and Repair
Supply And Return Line Replacement
TOOLS REQUIRED
J 37088-A, Fuel Line Separator Tool Set.
NOTICE:
^ If nylon fuel feed or return pipes becomes kinked, and cannot be straightened, they must be
replaced.
^ Do Not attempt to repair sections of nylon fuel pipes. If damaged, replace.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure. Refer to Fuel Delivery / Service and
Repair. 3. Quick-connect fittings at fuel rail in engine compartment. 4. Fuel feed and return pipe
retaining clip at brake booster. 5. Raise vehicle. 6. Quick-connect fittings at fuel filter. 7. Lower fuel
tank shield attaching screws and lower fuel tank shields. 8. Fuel feed, return, and EVAP pipe
underbody retainer. 9. Quick-connect fittings at fuel sender assembly.
10. Fuel feed and return pipe retaining clips and fuel feed and return pipes.
^ Note position of fuel pipes for installation.
INSTALL OR CONNECT
WARNING: To Reduce the Risk of Fire and Personal Injury:
^ If nylon fuel pipes are nicked, scratched or damaged during installation, they must be replaced.
^ When installing new fuel pipes, Do NOT hammer directly on the fuel harness body clips as this
may damage the nylon pipes resulting in a possible fuel leak.
1. Lower vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Supply Line > Component
Information > Description and Operation > Page 5179
2. Rear ends of fuel feed and return pipes into top forward frame hole. 3. Raise vehicle. 4. Route
pipes in same position as noted during disassembly. 5. Quick-connect fittings at fuel sender
assembly. 6. Fuel feed, return, and EVAP pipe underbody retainer. 7. Lower fuel tank shields and
tank shield attaching screws.
Tighten Lower fuel tank shield screws to 1 Nm (9 lb in.).
8. Quick-connect fittings at fuel filter. 9. Close all retaining clips.
10. Lower vehicle. 11. Fuel feed and return pipe retaining clip at brake booster. 12. Quick-connect
fittings at fuel rail in engine compartment. 13. Negative battery cable.
INSPECT
^ Turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank > Fuel Filler Pipe
<--> [Fuel Filler Hose] > Component Information > Specifications
Fuel Filler Pipe: Specifications
Fuel Filler Pipe Attaching Screws ........................................................................................................
......................................................... 6 Nm (53 lb in.)
Fuel Filler Pipe Ground Strap Screw
.............................................................................................................................................................
4 Nm (35 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank > Fuel Filler Pipe
<--> [Fuel Filler Hose] > Component Information > Specifications > Page 5184
Filler Pipe And Cap
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank > Fuel Filler Pipe
<--> [Fuel Filler Hose] > Component Information > Specifications > Page 5185
Fuel Filler Pipe: Description and Operation
Filler Pipe And Cap
The fuel tank filler pipe outlet is positioned at the rear of the vehicle. To prevent refueling with
leaded fuel the fuel filler pipe has a built-in restrictor and deflector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank > Fuel Gauge
Sender > Component Information > Locations
Fuel Gauge Sender: Locations
Mounted on Fuel Tank, Part of Fuel Tank Unit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank > Fuel Gauge
Sender > Component Information > Locations > Page 5189
Fuel Pump/Sender Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Specifications > Mechanical Specifications
Fuel Tank Unit: Mechanical Specifications
Fuel Sender Assembly Attaching Nuts
.......................................................................................................................................................... 3
Nm (27 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Specifications > Mechanical Specifications > Page 5194
Fuel Tank Unit: Pressure, Vacuum and Temperature Specifications
Fuel Pressure ......................................................................................................................................
......................................... 284 - 325 kPa (41 - 47 psi)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Locations > Component Locations
Fuel Tank Unit: Component Locations
Fuel Sender Assembly Replacement
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Locations > Component Locations > Page 5197
Fuel Sender Assembly
The fuel pump is located in the fuel tank as part of the fuel level sender assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Locations > Component Locations > Page 5198
Fuel Tank Unit: Connector Locations
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Locations > Component Locations > Page 5199
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Locations > Page 5200
Fuel Tank Unit: Description and Operation
Fuel Sender
Typical Rheostat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Locations > Page 5201
Fuel Sender
FUEL TANK UNIT
The fuel tank unit is located inside the fuel tank and is attached to the top of the fuel tank. The fuel
Tank Unit consists of the following major components: a fuel sender, fuel pump, and a fuel pump
strainer.
Fuel Sender Assembly The fuel sender consists of the float, wire float arm, rheostat and roll-over
valve. Fuel level is sensed by the position of the float and float arm which operate the 90 ohm
rheostat. As the float position changes, the amount of current passing through the rheostat varies,
thus changing the gage reading on the instrument panel.
The roll-over valve is pressed into the evaporative emission (EVAP) pipe of the fuel sender and is
not serviced separately. The roll-over valve prevents fuel from entering the evaporative emission
canister if the vehicle rolls over by shutting "OFF" the EVAP pipe to the canister.
Fuel Pump The fuel pump is an electric medium pressure twin turbine pump which is mounted to
the fuel sender assembly inside the fuel tank. The fuel is pumped to the fuel rail assembly at a
specified flow and pressure by the fuel pump. Excess fuel is returned to the fuel tank by the return
pipe. The fuel pump delivers a constant flow of fuel to the engine even during low fuel conditions
and aggressive vehicle maneuvers.
The electric fuel pump operation is controlled by the Powertrain Control Module (PCM) through a
fuel pump relay.
Fuel Pump Strainer A woven plastic fuel pump strainer is attached to the lower end of the fuel
pump in the fuel tank. The functions of the fuel pump strainer are to filter contaminants and to wick
fuel.
The life of the fuel pump strainer is generally considered to be that of the fuel pump. The fuel pump
strainer is self-cleaning and normally requires no maintenance. Fuel stoppage at this point
indicates that the fuel tank contains an abnormal amount of sediment or water. In which case the
tank should be thoroughly cleaned. (See "Fuel System Cleaning.") If the fuel pump strainer is
plugged, replace it with a new fuel pump strainer.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Service and Repair > Fuel Sender Assembly Replacement
Fuel Tank Unit: Service and Repair Fuel Sender Assembly Replacement
Fuel Sender Assembly Replacement
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Service and Repair > Fuel Sender Assembly Replacement > Page 5204
Fuel Sender Assembly
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure. Refer to Fuel Delivery / Service and
Repair. 3. Drain fuel tank. 4. Fuel tank assembly. 5. Fuel sender assembly attaching nuts, retaining
flange, fuel sender assembly and O-ring from fuel tank. Discard O-ring.
CLEAN
^ Fuel sender assembly sealing surfaces.
INSTALL OR CONNECT
NOTICE:
^ Care should be taken not to fold over or twist the fuel pump strainer when installing the fuel
sender assembly as this will restrict fuel flow. Also, assure that the fuel pump strainer does not
block full travel of float arm.
1. Position new 0-ring on fuel tank. 2. Fuel sender assembly, retaining flange and fuel sender
assembly attaching nuts.
Tighten Fuel sender assembly attaching nuts to 3 Nm (27 lb in.).
3. Fuel tank. 4. Add fuel and install fuel filler cap. 5. Negative battery cable.
INSPECT
^ Turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Service and Repair > Fuel Sender Assembly Replacement > Page 5205
Fuel Tank Unit: Service and Repair Fuel Pump Replacement
Fuel Sender Assembly Replacement
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Service and Repair > Fuel Sender Assembly Replacement > Page 5206
Fuel Sender Assembly
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Relieve fuel system pressure. Refer to Fuel Delivery / Service and
Repair. 3. Drain fuel tank. 4. Remove fuel tank assembly. 5. Remove fuel tank unit.
DISASSEMBLE
1. Note position of fuel pump strainer on fuel pump. 2. Support sender with one hand and grasp
strainer with other hand. Rotate strainer in one direction and pull off of pump. Discard strainer after
inspection.
3. Loosen clamp and remove connecting hose from fuel pump outlet 4. Remove terminal retainer.
5. Disconnect fuel pump electrical connector and electrical connector from bottom of sender cover.
6. Remove retainer clip from fuel return pipe. 7. Remove fuel pump and level sensor assembly and
spring from fuel sender. 8. Remove housing cover from fuel pump housing. 9. Fuel pump.
INSPECT AND REPLACE
1. Fuel pump strainer. If strainer is contaminated, it must be replaced and the fuel tank should be
removed and cleaned. 2. Always install a new pump strainer when replacing the fuel pump. 3. Fuel
pump inlet for dirt and debris.
ASSEMBLE 1. Install fuel level sensor to fuel pump housing. 2. Install fuel pump and isolator into
fuel pump housing.
NOTICE:
^ Small hole in the housing cover aligns over the fuel level sensor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Fuel Tank Unit > Component
Information > Service and Repair > Fuel Sender Assembly Replacement > Page 5207
3. Connect housing cover to fuel pump housing. 4. Slide fuel pump and fuel level sensor assembly
and spring onto fuel return pipe.
NOTICE:
^ Fuel pump and fuel level sensor assembly must be aligned directly under fuel sender cover.
5. Depress spring and install retainer. 6. Connect hose to outlet and tighten clamp so that 5-8 teeth
are engaged. 7. Connect fuel pump electrical connector and electrical connector to bottom of
sender cover. 8. Install terminal retainer. 9. Support sender with one hand and position new pump
strainer on pump in same position as noted during disassembly.
INSTALL OR CONNECT
1. Install fuel tank unit. 2. Install fuel tank assembly. 3. Add fuel and install filler cap. 2. Negative
battery cable.
INSPECT
^ Turn ignition switch to "ON" position for two seconds, then turn to "OFF" for ten seconds. Again
turn to "ON" position and check for fuel leaks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Specifications
Idle Air Control (IAC): Specifications
Idle Air Control (IAC) Valve Screws
............................................................................................................................................................
3 Nm (27 lb in.)
IAC Valve/Coolant Cover Assembly Screws
............................................................................................................................................. 3.2 Nm
(28 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Specifications > Page 5211
Idle Air Control (IAC): Locations
Component Location - Pictorial View
Throttle Body
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Specifications > Page 5212
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Diagrams > Diagram Information and Instructions
Idle Air Control (IAC): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Diagrams > Diagram Information and Instructions > Page
5215
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Diagrams > Diagram Information and Instructions > Page
5216
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Diagrams > Diagram Information and Instructions > Page
5217
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Diagrams > Diagram Information and Instructions > Page
5218
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Diagrams > Diagram Information and Instructions > Page
5219
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Idle Air Control (IAC): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Idle Air Control (IAC) Valve
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Idle Air Control (IAC) Circuit
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Idle Air Control (IAC): Description and Operation
Throttle Body
IAC Valve Flow
The purpose of the Idle Air Control (IAC) valve assembly is to control engine idle speed while
preventing stalls do to changes in engine load.
The IAC valve, mounted in the throttle body, controls a portion of the bypass air. An orifice located
between the throttle valves also supplies a constant amount of bypass air. By moving a conical
valve known as a pintle, IN, towards the seat (to decrease air flow) or OUT, away from the seat (to
increase air flow) a controlled amount of air can be bypassed. If engine speed is too low, more air
is bypassed to increase RPM. If engine speed is too high, less air is bypassed to decrease RPM.
The Powertrain Control Module (PCM) moves the IAC valve in small steps, called counts. These
can be measured and displayed by a scan tool which plugs into the Data Link Connector (DLC).
During idle, the proper position of the IAC valve is calculated by the PCM, based on battery
voltage, coolant temperature, engine load, and engine RPM. If the RPM drops below specification
and the throttle valve is closed, the PCM senses a near stall condition and calculates a new valve
position to prevent stalling.
^ Engine idle speed is a function of total air flow into the engine based on IAC valve pintle position
+ crankcase ventilation valve flow + throttle
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valve opening + bypass orifice air flow + calibrated vacuum loss through accessories.
^ Controlled idle speed is programmed into the PCM, which determines the correct lAC valve pintle
position to maintain the desired idle speed for all engine operating conditions and loads.
^ The minimum idle air rate is set at the factory with a stop screw. This setting allows enough air
flow by the throttle valves to cause the IAC valve pintle to be positioned a calibrated number of
steps (counts), from the seat, during controlled idle operation.
^ If the IAC valve is disconnected and reconnected with the engine running, the idle speed may be
wrong. If this occurs, reset the IAC valve by depressing the accelerator pedal slightly, start and run
engine for five seconds, then turn ignition "OFF" for ten seconds.
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Idle Air Control (IAC): Adjustments
To reset Idle Air Control (IAC) valve.
1. Depress accelerator pedal slightly. 2. Start and run engine for 5 seconds. 3. Turn ignition "OFF"
for 10 seconds. 4. Restart engine and check for proper idle operation.
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Procedure
Idle Air Control (IAC): Service and Repair Idle Air Control (IAC) Reset Procedure
1. Depress the accelerator pedal slightly. 2. Start and run the engine for five seconds. 3. Turn the
ignition "OFF" for ten seconds. 4. Restart the engine and check for proper idle operation.
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Procedure > Page 5253
Idle Air Control (IAC): Service and Repair Idle Air Control (IAC) Valve Replacement
Throttle Body Exploded View
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IAC Valve
REMOVE OR DISCONNECT
1. Resonator. 2. Distributor ventilation vacuum line at air intake duct. 3. Electrical connector from
Intake Air Temperature (IAT) sensor. 4. Air intake duct. 5. Electrical connector from Idle Air Control
(IAC) valve. 6. IAC valve assembly attaching screws. 7. IAC valve assembly.
CLEAN AND INSPECT
^ Clean IAC valve O-ring sealing surface, pintle valve seat and air passage. The IAC valve may be cleaned using GM cleaner 1052626 or GM X-66A. Use a shop towel or parts
brush to remove heavy deposits.
- Shiny spots on the pintle or seat are normal, and do not indicate misalignment or a bent pintle
shaft. If air passage has heavy deposits, remove throttle body for complete cleaning.
^ Inspect IAC valve O-ring for cuts, cracks, or distortion. Replace if damaged.
NOTICE: If installing a new IAC valve, be sure to replace with an identical part. IAC valve pintle
shape and diameter are designed for specific application.
MEASURE (IF INSTALLING A NEW IAC)
^ Distance between tip of IAC valve pintle and mounting surface. If greater than 28 mm (1.100 in), use finger pressure to slowly retract the pintle. The force required
to retract the pintle of a NEW valve will not cause damage to the valve.
INSTALL OR CONNECT
1. Lubricate IAC valve O-ring with clean engine oil. 2. IAC Valve assembly. 3. IAC valve attaching
screws.
Tighten ^
IAC attaching screws to 3 Nm (27 lb in.).
4. Electrical connector to IAC valve. 5. Air intake duct. 6. Electrical connector to IAT valve. 7.
Distributor ventilation vacuum line at air intake duct. 8. Resonator. 9. Reset IAC valve pintle
position.
A. Depress accelerator slightly. B. Start engine and release accelerator pedal, run engine for 5
seconds. C. Turn engine "OFF" for 10 seconds. D. Restart engine and check for proper idle
operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Service and Repair > Idle Air Control (IAC) Reset
Procedure > Page 5255
Idle Air Control (IAC): Service and Repair Idle Air Control/Coolant Cover Assembly
Throttle Body Exploded View
REMOVE OR DISCONNECT
2. Negative battery cable. 2. Throttle body from intake manifold.
^ Refer to Throttle Body / Service and Repair.
DISASSEMBLE
1. Idle Air Control (IAC) valve. 2. IAC valve/coolant cover assembly screws. 3. IAC valve/coolant
cover assembly and gasket.
^ Discard gasket
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Idle Air Control (IAC) <--> [Idle
Speed/Throttle Actuator - Electronic] > Component Information > Service and Repair > Idle Air Control (IAC) Reset
Procedure > Page 5256
CLEAN AND INSPECT 1. Clean gasket sealing surface. 2. Inspect gasket sealing surface for
corrosion or damage that would cause a coolant leak. Replace cover assembly or throttle body if
necessary.
ASSEMBLE 1. Install new gasket and cover assembly. 2. IAC Valve / coolant cover assembly
screws.
Tighten ^
IAC Valve / coolant cover assembly screws to 3.2 Nm (28 lb in.).
3. If installing a new IAC valve, measure distance between pintle and mounting surface. If greater
than 28mm, use finger pressure to slowly retract
the pintle.
INSTALL OR CONNECT
1. Install and tighten IAC valve attaching screws
Tighten ^
IAC Valve assembly screws to 3 Nm (27 lb in.).
2. Install throttle body to intake manifold. 3. Negative battery cable. 4. Reset IAC valve pintle
position. Refer to ADJUSTMENTS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Oil Pressure Switch (For Fuel
Pump) > Component Information > Specifications
Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Oil Pressure Switch (For Fuel
Pump) > Component Information > Locations > Fuel Pump/Engine Oil Pressure Indicator Switch
Rear Of Engine
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Oil Pressure Switch (For Fuel
Pump) > Component Information > Locations > Fuel Pump/Engine Oil Pressure Indicator Switch > Page 5262
Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Oil Pressure Switch (For Fuel
Pump) > Component Information > Diagrams > Diagram Information and Instructions
Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5267
Fig.1-Symbols (Part 1 Of 3)
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5268
Fig.2-Symbols (Part 2 Of 3)
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5269
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5270
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5271
Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5272
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5273
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5274
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Fuel Pump Switch/Engine Oil Pressure Gage Sensor
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Pump) > Component Information > Diagrams > Diagram Information and Instructions > Page 5297
Fuel Pump Relay Circuit
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Pump) > Component Information > Diagrams > Page 5298
Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Relays and Modules - Fuel
Delivery and Air Induction > Fuel Pump Relay > Component Information > Locations
Fuel Pump Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
Fuel Pump Relay: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
> Page 5306
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
> Page 5308
Fig.1-Symbols (Part 1 Of 3)
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
> Page 5309
Fig.2-Symbols (Part 2 Of 3)
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
> Page 5310
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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> Page 5311
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
> Page 5312
Fuel Pump Relay: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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> Page 5313
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Diagram Information and Instructions
> Page 5336
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Delivery and Air Induction > Fuel Pump Relay > Component Information > Diagrams > Page 5337
Fuel Pump Relay: Description and Operation
When the ignition switch is turned to the "ON" position (before engaging starter), the energizes the
fuel pump relay for two seconds causing the fuel pump to pressurize the fuel system. If the
Powertrain Control Module (PCM) does not receive ignition reference pulses (engine cranking or
running) within two seconds, it shuts "OFF" the fuel pump relay, causing the fuel pump to stop.
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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Fuel Pump Relay: Service and Repair
Fuel Pump (Circuit Opening) Relay
REMOVE OR DISCONNECT
1. Underhood (U/H) electrical center cover. 2. Fuel pump relay.
INSTALL OR CONNECT
1. Fuel pump relay. 2. Underhood (U/H) electrical center cover.
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Component Information > Locations
Powertrain Control Module (PCM)
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Powertrain Control Module (PCM)
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5347
Powertrain Control Module (PCM)
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions
Air Flow Meter/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5350
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Instructions > Page 5351
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5352
Fig.1-Symbols (Part 1 Of 3)
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5353
Fig.2-Symbols (Part 2 Of 3)
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Instructions > Page 5354
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Instructions > Page 5355
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5356
Air Flow Meter/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Instructions > Page 5357
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Instructions > Page 5380
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5381
MAF Sensor Circuit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Delivery and Air Induction > Air Flow Meter/Sensor > Component Information > Diagrams > Page 5382
Air Flow Meter/Sensor: Description and Operation
The Mass Air Flow (MAF) sensor measures the amount of air that is ingested by a vehicles' engine.
This information is required by the engine's Powertrain Control Module (PCM) to schedule fuel and
maintain the desired air/fuel ratio.
The MAF sensor used on this vehicle is a hot wire type and is used to measure air flow rate. The
Mass Air Flow (MAF) output frequency is a function of the power required to keep the air flow
sensing elements (hot wires) at a fixed temperature above ambient temperature. As air flows
through the MAF sensor the "hot wires" are cooled. The amount of cooling is proportional to the
rate of air flow. As air flow increases a greater amount of current is required to maintain the "hot
wires" at a constant temperature. The MAF sensor converts the changes in current draw to a
frequency signal read by the PCM. The PCM calculates air flow (grams per second) based on this
signal. A failure in the MAF circuit should set a Diagnostic Trouble Code (DTC) 48.
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Air Flow Meter/Sensor: Service and Repair
Mass Air Flow Removal
CAUTION: Take care when handling the Mass Air Flow (MAF). Do not dent, puncture, or otherwise
damage the Honeycell located at the air inlet end of the MAF. Do not touch the sensing elements
or allow anything (including cleaning solvents and lubricants) to come in contact with them. A small
amount of GM lubricant (P/N = 99855406) may be used on the air duct only, to aid in installation.
Do not drop or roughly handle the MAF.
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Electrical connector. 3. Carefully loosen air duct clamps and remove
MAF sensor.
NOTICE: Embossed arrows on MAF sensor indicate air flow and must point toward engine.
INSTALL OR CONNECT
1. MAF sensor into air duct. 2. Tighten clamps to 4 Nm (36 lb in.). 3. Electrical connector. 4.
Negative battery cable.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Specifications
Oil Pressure Switch (For Fuel Pump): Specifications
Fuel Pump Switch and Engine Oil Pressure Sensor
................................................................................................................................... 12 Nm (106 lb
in.)
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Locations > Fuel
Pump/Engine Oil Pressure Indicator Switch
Rear Of Engine
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Locations > Fuel
Pump/Engine Oil Pressure Indicator Switch > Page 5389
Oil Pressure Switch (For Fuel Pump): Locations Oil Pressure Sensor/Fuel Pump Switch
Fuel Pump - Oil Pressure Switch
The sensor is threaded into a TEE fitting at the rear of the engine.
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Information and Instructions
Oil Pressure Switch (For Fuel Pump): Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5392
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5394
Fig.1-Symbols (Part 1 Of 3)
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5395
Fig.2-Symbols (Part 2 Of 3)
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5396
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Information and Instructions > Page 5397
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5398
Oil Pressure Switch (For Fuel Pump): Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5399
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5418
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5419
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5420
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5421
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5422
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5423
Fuel Pump Switch/Engine Oil Pressure Gage Sensor
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Diagram
Information and Instructions > Page 5424
Fuel Pump Relay Circuit
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Page 5425
Oil Pressure Switch (For Fuel Pump): Description and Operation
Fuel Pump - Oil Pressure Switch
As a backup system to the fuel pump relay the fuel pump also can be energized by the fuel pump
switch and engine oil pressure sensor. The sensor has two internal circuits. One operates the oil
pressure indicator or gage on the instrument cluster, and the other is a normally open switch which
closes when oil pressure reaches about 28 kPa (4 psi). If the fuel pump relay fails, the fuel pump
switch and engine oil pressure sensor runs the fuel pump.
An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold.
The fuel pump switch and engine oil pressure sensor energizes the fuel pump as soon as oil
pressure reaches about 28 kPa (4 psi).
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Delivery and Air Induction > Oil Pressure Switch (For Fuel Pump) > Component Information > Diagrams > Page 5426
Oil Pressure Switch (For Fuel Pump): Service and Repair
Fuel Pump - Oil Pressure Switch
REMOVE OR DISCONNECT
1. Disconnect electrical connector. 2. Fuel pump switch and oil pressure sensor.
INSTALL OR CONNECT
1. Fuel pump switch and oil pressure sensor. 2. Tighten to 12 Nm (106 lb in.) 3. Electrical
connector.
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Specifications
Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Specifications > Page 5430
Throttle Position Sensor: Locations
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Specifications > Page 5431
Component Location - Pictorial View
Throttle Body
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions
Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5434
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Instructions > Page 5435
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5436
Fig.1-Symbols (Part 1 Of 3)
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5437
Fig.2-Symbols (Part 2 Of 3)
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5438
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5439
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5440
Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5441
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Instructions > Page 5442
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Sensors and Switches - Fuel
Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5459
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Sensors and Switches - Fuel
Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5460
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5461
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5462
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5463
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Sensors and Switches - Fuel
Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5464
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Sensors and Switches - Fuel
Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Diagram Information and
Instructions > Page 5465
Throttle Position Sensor Circuit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Sensors and Switches - Fuel
Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Page 5466
Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Sensors and Switches - Fuel
Delivery and Air Induction > Throttle Position Sensor > Component Information > Diagrams > Page 5467
Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Specifications
Throttle Body: Specifications
Throttle Body Attaching Bolts ..............................................................................................................
........................................................ 25 Nm (18 lb ft) Clean Air Cover Attaching Screws
..............................................................................................................................................................
3.2 Nm (28 lb in)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Specifications > Page 5471
Throttle Body Removal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Specifications > Page 5472
Throttle Body: Application and ID
Throttle Body Id
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Specifications > Page 5473
Throttle Body Exploded View
An eight digit part identification number is stamped on the throttle body casting as shown in the
image. Refer to this number if servicing or part replacement is required. For identification of parts
during repair, refer to the disassembled view image.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Specifications > Page 5474
Throttle Body: Description and Operation
Throttle Body
The throttle body assembly is attached to the intake manifold and is used to control air flow into the
thereby controlling engine output. The throttle valves within the throttle body are opened by the
vehicle operator through the accelerator controls. During engine idle, the throttle valves are almost
closed. and air flow control is handled by a fixed air bypass orifice and the Idle Air Control (IAC)
valve. To prevent throttle valve icing during cool weather operation, engine coolant is directed
through the coolant cavity on the bottom of the throttle body.
The throttle body also provides the location for mounting the Throttle Position (TP) sensor and for
sensing changes in engine vacuum due to throttle valve position. Vacuum points are located at,
above, or below the throttle valve to generate vacuum signals needed by various components.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Specifications > Page 5475
Throttle Body: Adjustments
To reset Idle Air Control (IAC) valve.
1. Depress accelerator pedal slightly. 2. Start and run engine for 5 seconds. 3. Turn ignition "OFF"
for 10 seconds. 4. Restart engine and check for proper idle operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket
Throttle Body: Service and Repair Clean Air Cover and Gasket
Throttle Body Exploded View
REMOVE OR DISCONNECT
1. Resonator. 2. Clean air cover attaching screws. 3. Clean air cover and gasket.
^ Discard the gasket.
CLEAN
^ Gasket sealing surfaces.
INSTALL OR CONNECT
1. Clean air cover gasket on the throttle body.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5478
2. Clean air cover. 3. Attaching screws.
Tighten ^
Attaching screws to 3.2 Nm (28 lb in.).
4. Resonator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5479
Throttle Body: Service and Repair Idle Air Control/Coolant Cover Assembly
Throttle Body Exploded View
REMOVE OR DISCONNECT
2. Negative battery cable. 2. Throttle body from intake manifold.
^ Refer to Throttle Body / Service and Repair.
DISASSEMBLE
1. Idle Air Control (IAC) valve. 2. IAC valve/coolant cover assembly screws. 3. IAC valve/coolant
cover assembly and gasket.
^ Discard gasket
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5480
CLEAN AND INSPECT 1. Clean gasket sealing surface. 2. Inspect gasket sealing surface for
corrosion or damage that would cause a coolant leak. Replace cover assembly or throttle body if
necessary.
ASSEMBLE 1. Install new gasket and cover assembly. 2. IAC Valve / coolant cover assembly
screws.
Tighten ^
IAC Valve / coolant cover assembly screws to 3.2 Nm (28 lb in.).
3. If installing a new IAC valve, measure distance between pintle and mounting surface. If greater
than 28mm, use finger pressure to slowly retract
the pintle.
INSTALL OR CONNECT
1. Install and tighten IAC valve attaching screws
Tighten ^
IAC Valve assembly screws to 3 Nm (27 lb in.).
2. Install throttle body to intake manifold. 3. Negative battery cable. 4. Reset IAC valve pintle
position. Refer to ADJUSTMENTS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5481
Throttle Body: Service and Repair Throttle Body Assembly Removal and Replacement
Throttle Body Removal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5482
Throttle Body Exploded View
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Partially drain cooling system to allow hoses at throttle body to be
removed. 3. Resonator. 4. Electrical connectors from Intake Air Temperature (IAT) sensor. 5.
Distributor ventilation line at the air intake duct. 6. Air intake duct. 7. Electrical connectors from
Throttle Position (TP) sensor and Idle Air Control (IAC) valve. 8. Vacuum lines from throttle body. 9.
Coolant hoses from throttle body.
10. Accelerator control cable and cruise control cable. 11. Remove throttle body attaching bolts 12.
Remove throttle body assembly and flange gasket, discard gasket
CLEAN
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5483
^ Gasket sealing surfaces.
NOTICE: Use care in cleaning old gasket material from machined aluminum surfaces as sharp
tools may damage sealing surfaces.
INSTALL OR CONNECT
1. Throttle body assembly with new flange gasket. 2. Throttle body attaching bolts
Tighten ^
Throttle body attaching bolts to 15 Nm (11 lb ft.).
3. Accelerator control cable and cruise control cable. 4. Coolant hoses to throttle body. 5. Vacuum
lines to throttle body. 6. Electrical connectors to TP sensor and IAC valve. 5. Distributor ventilation
line at the air intake duct. 4. Electrical connectors from IAT sensor. 3. Resonator. 8. Refill cooling
system. 9. Connect negative battery cable
10. Ensure accelerator pedal is free. 11. Reset IAC valve position. Refer to ADJUSTMENT
PROCEDURES.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Body > Component
Information > Service and Repair > Clean Air Cover and Gasket > Page 5484
Throttle Body: Service and Repair Throttle Body Cleaning
CLEANING CAUTIONS
Do not soak the throttle body in cold immersion type cleaner. The throttle valves have a factory
applied sealing compound (DAG material is applied to outside edge of each valve and throttle bore)
to prevent air bypass at closed throttle. Strong solvents or brushing will remove the material. To
clean the throttle body following dissemble, use a spray type cleaner such as GM X66-A or GM
1052626. Use a shop towel to remove heavy deposits.
The Throttle Position (TP) sensor and Idle Air Control (IAC) valve are electrical components and
should NOT come in contact with solvent or cleaner, as they may be damaged.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Cable/Linkage >
Component Information > Locations
Sensor Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Cable/Linkage >
Component Information > Locations > Page 5488
Throttle Cable/Linkage: Service and Repair
Sensor Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Cable/Linkage >
Component Information > Locations > Page 5489
Accelerator Pedal
REMOVE OR DISCONNECT
1. Accelerator cable from accelerator pedal 2. Accelerator cable retainer 3. Squeeze accelerator
cable cover tangs and push cable through dash panel (Bulkhead). 4. Accelerator cable retaining
clip on resonator bracket. 5. Accelerator cable from accelerator cable bracket and throttle body.
NOTICE: To prevent possible interference, flexible components (hoses, wires, conduits etc.) must
not be routed within 50 mm (2 in.) of moving parts, unless routing is positively controlled.
INSTALL OR CONNECT
1. Accelerator cable cover through dash panel (bulkhead). 2. Accelerator cable retainer. 3.
Accelerator cable to accelerator pedal. 4. Accelerator cable to accelerator cable bracket and
throttle body. 5. Accelerator cable retaining clip on resonator bracket.
INSPECT
^ Check for complete throttle opening and closing positions by operating accelerator pedal. Also
check for poor carpet fit under the accelerator pedal. Throttle should operate freely without blind
between full closed and wide open throttle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Specifications
Throttle Position Sensor: Specifications
Throttle Position (TP) Sensor Screws
.......................................................................................................................................................... 2
Nm (18 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Specifications > Page 5493
Throttle Position Sensor: Locations
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Specifications > Page 5494
Component Location - Pictorial View
Throttle Body
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions
Throttle Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 5497
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Component Information > Diagrams > Diagram Information and Instructions > Page 5498
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5499
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5500
Fig.2-Symbols (Part 2 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5501
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Component Information > Diagrams > Diagram Information and Instructions > Page 5502
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Fuel Delivery and Air Induction > Throttle Position Sensor >
Component Information > Diagrams > Diagram Information and Instructions > Page 5503
Throttle Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Component Information > Diagrams > Diagram Information and Instructions > Page 5526
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Component Information > Diagrams > Diagram Information and Instructions > Page 5528
Throttle Position Sensor Circuit.
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Component Information > Diagrams > Page 5529
Throttle Position Sensor: Description and Operation
Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle
body and is one of the most important sensors for engine/transmission control. The TP sensor has
one end connected to 5 volts from the Powertrain Control Module (PCM) and the other to PCM
ground. A third wire is connected to the PCM to measure the voltage from the TP sensor. As the
throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also
changes.
At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As
the throttle valve opens. the output increases so that at wide open throttle, the output voltage
should be near 5.0 volts.
By monitoring the output voltage from the TP sensor, the PCM can determine fuel delivery based
on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts
of fuel from the injector and cause an unstable idle, because the PCM detects the throttle is
moving.
If the TP sensor circuit is open, the PCM will set a Diagnostic Trouble Code (DTC) 22. IF the TP
sensor circuit is shorted, the PCM will interpret this signal as wide open throttle and a DTC 21 will
be set A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set,
the PCM will use a default value for TP sensor, and some vehicle performance will return.
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Throttle Position Sensor: Service and Repair
Throttle Position Sensor
REMOVE OR DISCONNECT
1. Resonator. 2. Throttle Position Sensor (TPS) sensor electrical connector. 3. Remove two TP
sensor attaching screws. 4. TP sensor.
NOTICE: The TP sensor is an electrical component and must NOT be soaked in any liquid cleaner
or solvent as damage may result.
INSTALL OR CONNECT
1. With the throttle valve in the normally closed idle position, install throttle position sensor on
throttle body assembly, making sure TP sensor lever
lines up with the TP sensor drive lever on the throttle shaft.
2. TP sensor screws.
Tighten ^
TP sensor screws to 2.0 Nm (18.0 lb in.).
3. TP Electrical connector. 4. Resonator.
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Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Firing Order > Component Information >
Specifications > Ignition Firing Order
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Timing > Number One Cylinder >
Component Information > Locations > Number 1 Cylinder Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Timing > Timing Marks and Indicators
> System Information > Locations > Crankshaft Rotation
Timing Marks and Indicators: Locations Crankshaft Rotation
Crankshaft Rotation (Typical Crankshaft Pulley)
Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the
generic image.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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> System Information > Locations > Crankshaft Rotation > Page 5545
Timing Marks and Indicators: Locations Timing Marks
The ignition timing is completely controlled by the Powertrain Control Module (PCM). No timing
reference marks are provided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5606
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5607
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5608
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5609
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5610
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5611
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5612
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5613
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5614
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Crankshaft Position Sensor > Component
Information > Diagrams > Diagram Information and Instructions > Page 5615
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Distributor, Ignition > Distributor Cap >
Component Information > Specifications
Distributor Cap: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Distributor, Ignition > Distributor Cap >
Component Information > Service and Repair > Replacement
Distributor Cap: Service and Repair Replacement
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Distributor cap (30). 2. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten ^
Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
3. Vacuum harness assembly to distributor assembly. 4. Connect four-terminal PCM connector to
distributor. 5. Spark plug wire harness assemblies to distributor assembly. 6. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Distributor, Ignition > Distributor Cap >
Component Information > Service and Repair > Replacement > Page 5622
Distributor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Distributor, Ignition > Ignition Rotor >
Component Information > Specifications
Ignition Rotor: Specifications
Distributor Bolt / Screw ........................................................................................................................
..................................................... 12 Nm (106 lb in.)
Distributor Cap Bolt / Screw ................................................................................................................
..................................................... 2.8 N.m (25 lb in.)
Distributor Rotor Bolt / Screw ..............................................................................................................
....................................................... 0.7 Nm (6 lb in.)
Firing Order .........................................................................................................................................
............................................ 1 - 8 - 4 - 3 - 6 - 5 - 7 - 2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Distributor, Ignition > Ignition Rotor >
Component Information > Specifications > Page 5626
Ignition Rotor: Service and Repair
Cap - Rotor Assembly
Numbers used below refer to image caption.
TOOL REQUIRED
J 39997 Ignition Distributor Cap Socket J 39998 Ignition Distributor Rotor
REMOVE OR DISCONNECT
1. Water pump and crankshaft balancer. 2. Spark plug wire harness assemblies from distributor
assembly. 3. Four-terminal Powertrain Control Module (PCM) connector from distributor assembly.
4. Vacuum harness assembly from distributor assembly. 5. Distributor cap bolts / screws (29) using
J 39997 or equivalent. 6. Distributor cap (30). 7. Rotor bolts / screws (32) using J 39998 or
equivalent. 8. Rotor assembly (32). 9. Distributor cover (33) and shield (34).
NOTICE: Do not touch timing disk, sensor or distributor base.
INSPECT
^ Distributor base and timing disk, for damage, corrosion or plastic particles. If any are present
replace entire distributor assembly.
INSTALL OR CONNECT
1. Shield (34) and distributor cover (33). 2. Rotor (32). 3. Rotor bolts / screws (31) using J 39998 or
equivalent.
Tighten ^
Rotor bolts / screws (31) to 0.7 Nm (61 lb in.).
4. Distributor cap (30). 5. Distributor cap bolts / screws (29) using J 39997 or equivalent.
Tighten
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Distributor, Ignition > Ignition Rotor >
Component Information > Specifications > Page 5627
^ Distributor cap bolts / screws (29) to 2.8 Nm (25 lb in.).
6. Vacuum harness assembly to distributor assembly. 7. Connect four-terminal PCM connector to
distributor. 8. Spark plug wire harness assemblies to distributor assembly. 9. Crankshaft balancer
and water pump assemblies.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications
Spark Plug Wire: Specifications
Wire Harness Support Bolt / Screw
............................................................................................................................................................
40 Nm (30 lb ft.)
Wire Harness Support Channel Bolt / Screw (Right)
................................................................................................................................ 12 Nm (106 lb in.)
Wire Harness Support Channel Bolt/Screw (Left)
..................................................................................................................................... 12 Nm (106 lb
ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5631
Spark Plug Wire: Locations
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5632
Spark Plug Harness Routing
The spark plug wires run down both sides of the engine block under the exhaust manifolds.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5633
Spark Plug Wire: Description and Operation
The spark plug wire hamess assemblies use carbon impregnated cord conductors, encased in 8
mm (5 / 16-inch) diameter silicone jackets. The silicone jackets withstand very high temperatures
and also provide excellent insulation for the high voltage of the system. Silicone spark plug boots
form a tight seal to the spark plugs.
The material used to construct spark plug wires is very soft. This wire will withstand more heat and
carry a higher voltage, but chaffing and cutting become easier. The spark plug wires must be
routed correctly to prevent chafing or cutting. When removing a spark plug wire from a spark plug,
twist the boot on the spark plug one-half turn while pulling on the boot.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5634
Spark Plug Wire: Testing and Inspection
Inspect spark plug wires visually first for any cuts, burns, or damage. While engine is running,
inspect for any arcing to ground or other components. Use a spray bottle to lightly coat the spark
plug wires with water while observing idle quality. If idle quality diminishes or engine stalls, spark
plug wires should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5635
Spark Plug Wire: Service and Repair
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5636
Spark Plug Harness Routing
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5637
Spark Plug Harness Routing
NOTICE: The boots should be twisted one-half turn while removing. Do not pull on the wire
harnesses to remove them from the spark plugs. Pull on the boots, or use a tool designed for this
purpose.
REMOVE OR DISCONNECT
Numbers included in this procedure refer to caption numbers in the included images.
1. Left bank spark plug wire boots from spark plugs. 2. Left bank spark plug wire harness support
channel bolts / screws (19) and channel. Rear bolt / screw (19) is located behind exhaust manifold
takedown. Loosen this bolt / screw using a 10 mm wrench then slide channel upward to disengage
from bolt / screw (19).
3. Left bank spark plug wire harness from clip (17) located behind air injection reactor (AIR) pump.
4. Right bank spark plug wire boots from spark plugs. 5. Air intake resonator.
With mechanical cooling fan: A. Upper radiator fan shroud, B. Loosen fan pulley nuts. C. Fan belt.
D. Mechanical fan and pulley. E. Mechanical fan pulley bracket nuts and bracket. F. Radiator outlet
pipe nuts from A/C compressor mounting studs.
6. Serpentine drive belt. 7. Raise and suitably support vehicle. 8. Transmission oil cooler line
support bolt / screw from accessory drive bracket. 9. Serpentine drive belt tensioner bolts/screws
and tensioner.
10. A/C compressor attaching bolts/screws
Reposition A/C compressor to provide access to front wire harness support (27).
11. Right wire harness support bolt / screw (28). 12. Right wire harness from support (27). 13. Left
and right bank spark plug wire harnesses (6) from distributor. 14. Left wire harness from clips (17,
20, 21 and 23).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug Wire <--> [Ignition Cable] >
Component Information > Specifications > Page 5638
^ Insert screwdriver into tab on top of clip to disengage.
15. Right wire harness from clips (16, 17, and 21).
^ Insert screwdriver into tab on top of clip to disengage.
NOTICE: When replacing spark plug wire harnesses (secondary wiring), route the wire harnesses
correctly and through the proper retainers. Failure to
route the wire harnesses properly can lead to radio ignition noise and cross-firing of the spark
plugs, or shorting of the leads to ground.
INSTALL OR CONNECT
1. Right wire harness to clips (16, 17 and 21). 2. Left wire harness to clips (17, 20, 21 and 23). 3.
Right wire harness to support (27). 4. Right wire harness support bolt / screw (28).
Tighten ^
Bolt / screw (28) to 40 Nm (30 lb ft.).
5. A/C compressor to bracket. 6. A/C compressor attaching bolts / screws and rear bracket nut.
Tighten A. A/C compressor bolts / screws to 50 Nm (37 lb ft.). B. A/C compressor rear bracket nut
to 41 Nm (30 lb ft.).
7. Serpentine drive belt tensioner and tensioner bolts / screws.
Tighten ^
Tensioner bolts / screws to 25 Nm (18 lb ft.).
8. Transmission oil cooler line support bolt / screw.
Tighten ^
Oil cooler line support bolt / screw to 1.9 Nm (17 lb in.).
9. Lower vehicle.
10. Serpentine drive belt.
With mechanical cooling fan: A. Radiator outlet pipe nuts from A/C compressor mounting studs.
Tighten ^
Radiator outlet pipe nuts to 16 Nm (12 lb ft.).
B. Mechanical fan pulley bracket nuts and bracket.
Tighten ^
Mechanical fan pulley bracket nuts to 50 Nm (37 lb .ft).
C. Mechanical fan pulley, fan and nuts.
^ Finger tighten only.
D. Fan belt.
Tighten ^
Mechanical fan nuts to 26 Nm (19 lb ft.).
E. Upper radiator fan shroud.
11. Air intake resonator. 12. Right bank spark plug wire boots to spark plugs. 13. Left bank spark
plug wire harness to clip (17) located behind AIR pump. 14. Left bank spark plug wire harness
support channel and bolts/screws (19). Rear bolt / screw (19) is located behind exhaust manifold
takedown.
Slide channel onto bolt / screw (19) then tighten using a 10 mm wrench.
15. Left bank spark plug wire harness boots to spark plugs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Coil > Component Information >
Specifications > Electrical Specifications
Ignition Coil: Electrical Specifications
COIL PACK RESISTANCE SPECIFICATIONS:
^ The OEM service manual does not provide a specification for coil resistance.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Coil > Component Information >
Specifications > Electrical Specifications > Page 5643
Ignition Coil: Mechanical Specifications
Ignition Coil Assembly Bolt / Screw
...........................................................................................................................................................
25 Nm (18 lb ft.)
Ignition Coil Assembly Stud .................................................................................................................
...................................................... 25 Nm (18 lb ft.)
Ignition Coil Module Bolt / Screw
.............................................................................................................................................................
1.7 Nm (15 lb in.)
Replacement Gin. Coil to-Bracket Bolt / Screw
......................................................................................................................................... 2.8 Nm (25
lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Coil > Component Information >
Specifications > Page 5644
Ignition Coil: Locations
Engine Left Side Upper
Ignition Coil And Module Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Coil > Component Information >
Specifications > Page 5645
Ignition Coil: Description and Operation
Ignition Coil And Module Assembly
Ignition Coil And Module
The ignition coil/ignition control module assembly provides spark to the distributor assembly, timed
by signals from the ECM. Power (B+) for the ignition coil primary circuit and the ignition control
module is supplied by the ignition switch. The ECM combines the camshaft position information
supplied by the distributor with other system parameters and calculates the required spark advance
and coil dwell. The ECM signals the ignition control module, which turns on the primary current to
the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When
the primary current flow stops, high voltage induced in the ignition coil secondary winding becomes
the spark voltage for the spark plug. The spark voltage is delivered to the distributor assembly
through the coil output (secondary) wire, and then directed to the proper spark plug connector by
the distributor rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Coil > Component Information >
Specifications > Page 5646
Ignition Coil: Service and Repair
Ignition Coil
Ignition Coil And Ignition Control Module
Numbers used below refer to image caption.
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Four-terminal Powertrain Control
Module (PCM) connector at ignition coil module. 3. Ignition coil wiring connectors. 4. Ignition coil
harness.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Coil > Component Information >
Specifications > Page 5647
5. Studs (5). 6. Ignition coil / Ignition Control Module assembly (8).
^ Do not wipe silicone grease from bottom of ignition coil assembly (8) if it is to he reinstalled.
NOTICE: If a new ignition coil assembly is to be installed, a package of silicone grease will be
included in the box. This grease is necessary for ignition coil assembly cooling.
INSTALL OR CONNECT
1. Spread silicone grease on metal mounting face of ignition coil bracket (14) if necessary, and
position ignition coil / Ignition Control module
assembly (8) to cylinder head assembly.
2. Studs (5).
Tighten ^
Studs (5) to 25 Nm (18 lb ft.).
3. Ignition coil harness. 4. Ignition coil wiring connectors. 5. Four terminal PCM connector to
ignition coil module.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Control Module > Component
Information > Specifications
Ignition Control Module: Specifications
Ignition Coil Assembly Bolt / Screw
...........................................................................................................................................................
25 Nm (18 lb ft.)
Ignition Coil Assembly Stud .................................................................................................................
...................................................... 25 Nm (18 lb ft.)
Ignition Coil Module Bolt / Screw
.............................................................................................................................................................
1.7 Nm (15 lb in.)
Replacement Coil to-Bracket Bolt / Screw
................................................................................................................................................. 2.8 Nm
(25 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Control Module > Component
Information > Locations > Ignition Coil Module Connector
Engine Left Side Upper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Control Module > Component
Information > Locations > Ignition Coil Module Connector > Page 5653
Ignition Control Module: Locations Ignition Module
Ignition Coil
Ignition Coil And Ignition Control Module
The Ignition Control Module is located on the ignition coil bracket assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Control Module > Component
Information > Locations > Page 5654
Ignition Control Module: Description and Operation
Ignition Coil And Module Assembly
Ignition Coil And Module
The ignition coil/ignition control module assembly provides spark to the distributor assembly, timed
by signals from the ECM. Power (B+) for the ignition coil primary circuit and the ignition control
module is supplied by the ignition switch. The ECM combines the camshaft position information
supplied by the distributor with other system parameters and calculates the required spark advance
and coil dwell. The ECM signals the ignition control module, which turns on the primary current to
the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When
the primary current flow stops, high voltage induced in the ignition coil secondary winding becomes
the spark voltage for the spark plug. The spark voltage is delivered to the distributor assembly
through the coil output (secondary) wire, and then directed to the proper spark plug connector by
the distributor rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Control Module > Component
Information > Locations > Page 5655
Ignition Control Module: Service and Repair
Ignition Coil
Ignition Coil And Ignition Control Module
Numbers used below refer to image caption.
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Four-terminal Powertrain Control
Module (PCM) connector at ignition coil module. 3. Ignition coil wiring connectors. 4. Ignition coil
harness.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Ignition Control Module > Component
Information > Locations > Page 5656
5. Studs (5). 6. Ignition coil / Ignition Control Module assembly (8).
^ Do not wipe silicone grease from bottom of ignition coil assembly (8) if it is to he reinstalled.
DISASSEMBLE
1. Coil (10) from brackets (13 and 14) by drilling out rivets (9). 2. Bolts/screws (12). 3. Ignition
control module (11).
NOTICE: If a new ignition coil assembly is to be installed, a package of silicone grease will be
included in the box. This grease is necessary for ignition coil assembly cooling.
ASSEMBLE
1. Spread silicone grease on metal face of ignition control module (11) and on bracket (13) where it
seats, and position ignition control module (11)
to bracket (13).
2. Bolts / screws (12).
Tighten ^
Bolts / screws (12) to 1.7 Nm (15 lb in.).
3. Coil (10) to brackets (13 and 14) using bolts / screws provided with replacement coil (10).
Tighten ^
Bolts / screws to 2.8 Nm (25 lb in.).
INSTALL OR CONNECT
1. Spread silicone grease on metal mounting face of ignition coil bracket (14) if necessary, and
position ignition coil / Ignition Control module
assembly (8) to cylinder head assembly.
2. Studs (5).
Tighten ^
Studs (5) to 25 Nm (18 lb ft.).
3. Ignition coil harness. 4. Ignition coil wiring connectors. 5. Four terminal PCM connector to
ignition coil module.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Specifications
Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Locations > Component Locations
Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Locations > Component Locations > Page 5662
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions
Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5665
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5666
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5667
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5668
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5669
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5670
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5671
Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5672
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Diagrams > Diagram Information and Instructions > Page 5673
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Diagrams > Diagram Information and Instructions > Page 5674
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Diagrams > Diagram Information and Instructions > Page 5675
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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Diagrams > Diagram Information and Instructions > Page 5676
1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5692
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5693
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5694
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5695
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Diagram Information and Instructions > Page 5696
Knock Sensor Circuit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Page 5697
Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Page 5698
Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Knock Sensor > Component Information >
Diagrams > Page 5699
Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Relays and Modules - Ignition System >
Ignition Control Module > Component Information > Specifications
Ignition Control Module: Specifications
Ignition Coil Assembly Bolt / Screw
...........................................................................................................................................................
25 Nm (18 lb ft.)
Ignition Coil Assembly Stud .................................................................................................................
...................................................... 25 Nm (18 lb ft.)
Ignition Coil Module Bolt / Screw
.............................................................................................................................................................
1.7 Nm (15 lb in.)
Replacement Coil to-Bracket Bolt / Screw
................................................................................................................................................. 2.8 Nm
(25 lb in.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Relays and Modules - Ignition System >
Ignition Control Module > Component Information > Locations > Ignition Coil Module Connector
Engine Left Side Upper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Relays and Modules - Ignition System >
Ignition Control Module > Component Information > Locations > Ignition Coil Module Connector > Page 5706
Ignition Control Module: Locations Ignition Module
Ignition Coil
Ignition Coil And Ignition Control Module
The Ignition Control Module is located on the ignition coil bracket assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Relays and Modules - Ignition System >
Ignition Control Module > Component Information > Locations > Page 5707
Ignition Control Module: Description and Operation
Ignition Coil And Module Assembly
Ignition Coil And Module
The ignition coil/ignition control module assembly provides spark to the distributor assembly, timed
by signals from the ECM. Power (B+) for the ignition coil primary circuit and the ignition control
module is supplied by the ignition switch. The ECM combines the camshaft position information
supplied by the distributor with other system parameters and calculates the required spark advance
and coil dwell. The ECM signals the ignition control module, which turns on the primary current to
the ignition coil by grounding the primary circuit, and then turns it off by removing the ground. When
the primary current flow stops, high voltage induced in the ignition coil secondary winding becomes
the spark voltage for the spark plug. The spark voltage is delivered to the distributor assembly
through the coil output (secondary) wire, and then directed to the proper spark plug connector by
the distributor rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Relays and Modules - Ignition System >
Ignition Control Module > Component Information > Locations > Page 5708
Ignition Control Module: Service and Repair
Ignition Coil
Ignition Coil And Ignition Control Module
Numbers used below refer to image caption.
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Four-terminal Powertrain Control
Module (PCM) connector at ignition coil module. 3. Ignition coil wiring connectors. 4. Ignition coil
harness.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Relays and Modules - Ignition System >
Ignition Control Module > Component Information > Locations > Page 5709
5. Studs (5). 6. Ignition coil / Ignition Control Module assembly (8).
^ Do not wipe silicone grease from bottom of ignition coil assembly (8) if it is to he reinstalled.
DISASSEMBLE
1. Coil (10) from brackets (13 and 14) by drilling out rivets (9). 2. Bolts/screws (12). 3. Ignition
control module (11).
NOTICE: If a new ignition coil assembly is to be installed, a package of silicone grease will be
included in the box. This grease is necessary for ignition coil assembly cooling.
ASSEMBLE
1. Spread silicone grease on metal face of ignition control module (11) and on bracket (13) where it
seats, and position ignition control module (11)
to bracket (13).
2. Bolts / screws (12).
Tighten ^
Bolts / screws (12) to 1.7 Nm (15 lb in.).
3. Coil (10) to brackets (13 and 14) using bolts / screws provided with replacement coil (10).
Tighten ^
Bolts / screws to 2.8 Nm (25 lb in.).
INSTALL OR CONNECT
1. Spread silicone grease on metal mounting face of ignition coil bracket (14) if necessary, and
position ignition coil / Ignition Control module
assembly (8) to cylinder head assembly.
2. Studs (5).
Tighten ^
Studs (5) to 25 Nm (18 lb ft.).
3. Ignition coil harness. 4. Ignition coil wiring connectors. 5. Four terminal PCM connector to
ignition coil module.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions
Camshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5715
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5716
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5717
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5718
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5719
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5720
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5721
Camshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5722
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5723
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Camshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5724
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Crankshaft Position Sensor > Component Information > Diagrams > Diagram Information and Instructions
Crankshaft Position Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Crankshaft Position Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Knock Sensor > Component Information > Specifications
Knock Sensor: Specifications
Knock (KS) Sensor ..............................................................................................................................
........................................................ 19 Nm (14 lb ft.)
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Knock Sensor > Component Information > Locations > Component Locations
Knock Sensor: Component Locations
Engine, Left Side Lower
Lower Right Side Of Engine
There are two knock sensors (KS), located in the engine block, one on each side.
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Engine Harness/U/Hood Electrical Center, Right Side
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Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions
Knock Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Knock Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5815
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5816
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5817
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5818
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5819
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Diagram Information and Instructions > Page 5820
Knock Sensor Circuit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Page 5821
Knock Sensor: Description and Operation
Knock Sensor (KS) Sensor
Knock Sensor Cut-away
Varying octane levels in today's gasoline can cause detonation in high performance engines.
Detonation is sometimes called spark knock. To control spark knock, a Knock Sensor (KS) system
is used. This system is designed to retard spark timing up to 20° to reduce spark knock in the
engine. This allows the engine to use maximum spark advance to improve driveability and fuel
economy.
The knock sensor system is used to detect engine detonation. The Powertrain Control Module
(PCM) will retard the spark timing based on signals from the KS module. The knock sensors
produce an AC voltage which is sent to the KS module. The amount of AC voltage produced by the
sensors is determined by the amount of knock. This signal voltage is input to the PCM. The PCM
then adjusts the Ignition Control (IC) to reduce spark knocking.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Page 5822
Knock Sensor: Testing and Inspection
The Tech 1 (or equivalent) has several positions for diagnosing the Knock Sensor (KS) circuit.
"Knock signal" is used to monitor the input signal from the knock sensor. This position should
display "YES" to indicate when a knock is being detected. "Knock retard" is the indication of how
much the Powertrain Control Module (PCM) is retarding the spark. Diagnostic Trouble Code (DTC)
43 is designed to diagnose the knock sensor circuit. Problems encountered with this circuit should
set DTC 43. However, if no DTC 43 was set but the KS system is suspected, refer to CHART C-5.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Sensors and Switches - Ignition System >
Knock Sensor > Component Information > Diagrams > Page 5823
Knock Sensor: Service and Repair
REMOVE OR DISCONNECT
1. Negative battery cable. 2. Drain cooling system. 3. Raise vehicle. 4. Wiring harness connector
from knock sensor.
WARNING: Engine coolant may be hot. The knock sensor is mounted in the engine block cooling
passage. Engine coolant will drain when the knock sensor is removed.
5. Knock sensor from block.
NOTICE: Do NOT apply thread sealant to sensor threads. Sensor is coated at factory and applying
additional sealant will affect the sensor's ability to detect detonation.
INSTALL OR CONNECT
1. Knock sensor into block.
Tighten ^
Sensor to 19 Nm (14 lb ft.).
2. Wiring harness connector to knock sensor. 3. Lower vehicle. 4. Refill cooling system and
pressure test for leaks. 5. Negative battery cable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications
Spark Plug: Specifications
Spark Plug Install Torque ....................................................................................................................
........................................................ 27 Nm (20 lb ft.)
Spark Plug Gap ...................................................................................................................................
........................................................ 1.27 mm (0.050")
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications > Page 5827
Spark Plug Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications > Page 5828
Spark Plug: Service Precautions
It is important that technicians wash their hands after handling coated spark plugs and before
smoking. The coating itself is a nonhazardous material and incidental contact will not cause any
adverse affects. However, exposure to polymer vapors (the result of a cigarette being coated from
handling, then burned) may cause flu like symptoms and should be avoided.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications > Page 5829
Spark Plug ID
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications > Page 5830
Spark Plug: Description and Operation
Platinum-tipped, resistor-type, tapered-seat spark plugs are used on the engine assembly. No
gasket is used on these tapered-seat spark plugs. When replacing spark plugs, use only the type
specified.
Normal service is assumed to be a mixture of idling, slow speed, and high speed driving.
Occasional or intermittent high-speed driving is needed for good spark plug performance. It gives
increased combustion heat, burning away carbon or oxides that have built up from frequent idling,
or continual stop-and-go driving.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications > Page 5831
Spark Plug: Testing and Inspection
WORN OR DIRTY
Worn or dirty spark plugs may give satisfactory operation at idling speed, but frequently fail at
higher rpm. Faulty spark plugs may cause poor fuel economy, power loss, loss of speed, hard
starting and generally poor engine performance. Follow the scheduled maintenance service
recommendations to assure satisfactory spark plug performance.
NORMAL
Normal spark plug operation will result in brown to grayish - tan deposits appearing on the portion
of the spark plug that projects into the cylinder area. A small amount of red - brown, yellow, and
white powdery material may also be present on the insulator tip around the center electrode. These
deposits are normal combustion by-products of fuels and lubricating oils with additives.
MISFIRING
Engine assemblies which are not running properly are often referred to as "misfiring." This means
the ignition spark is not igniting the fuel/air mixture at the proper time, While other ignition and fuel
system causes must also be considered, possible causes include ignition system conditions which
allow the spark voltage to reach ground in some other manner than by jumping across the air gap
at the tip of the spark plug, leaving the fuel/air mixture unburned. Misfiring may also occur when the
tip of the spark plug becomes overheated and ignites the mixture before the spark jumps. This is
referred to as "pre-ignition."
CARBON FOULING
Carbon fouling of the spark plug is indicated by dry, black carbon (soot) deposits on the portion of
the spark plug in the cylinder. Excessive idling and slow speeds under light engine loads can keep
the spark plug temperatures so low that these deposits are not burned off. Over - rich fuel mixtures
or poor ignition system output may also be the cause.
OIL FOULING
Oil fouling of the spark plug is indicated by wet oily deposits on the portion of the spark plug in the
cylinder. This may be caused by oil getting past worn piston rings. This condition also may occur
during break-in of new or newly overhauled engine assemblies.
DEPOSITS
Deposit fouling of the spark plug occurs when the normal red - brown, yellow or white deposits of
combustion by - products become sufficient to cause misfiring. In some cases, these deposits may
melt and form a shiny glaze on the insulator around the center electrode. If the fouling is found in
only one or two cylinders, valve stem clearances or intake valve seals may be allowing excess
lubricating oil to enter the cylinder, particularly if the deposits are heavier on the side of the spark
plug that was facing the intake valve.
CRACKED OR BROKEN
Cracked or broken insulators may be the result of improper installation or heat shock to the
insulator material. Upper insulators can be broken when a poorly fitting tool is used during
installation or removal, or when the park plug is hit from the outside. Cracks in the upper insulator
may be inside the shell and not visible. Also, the breakage may not cause problems until oil or
moisture penetrates the crack later.
A broken or cracked lower insulator tip (around the center electrode) may result from "heat shock"
(spark plug suddenly operating too hot).
"Heat shock" breakage in the lower insulator tip generally occurs during severe engine operating
conditions (high speeds or heavy loading) and may be caused by over - advanced timing or low
grade fuels. Heat shock refers to a rapid increase in the tip temperature that causes the insulator
material to crack.
Damage during gapping can happen if the gapping tool is pushed against the center electrode or
the insulator around it, causing the insulator to crack. When gapping a spark plug, make the
adjustment by only bending the ground side terminal, keeping the tool clear of other parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Ignition System > Spark Plug > Component Information >
Specifications > Page 5832
Spark Plug: Service and Repair
Spark Plug Assembly
REMOVE OR DISCONNECT
1. Be sure ignition switch is in "OFF" or "LOCK" position. 2. Spark plug wire harness assemblies
from spark plugs. Refer to "Spark Plug Wire Harness Assembly Replacement" in this section.
^ Note positions of wires before removing.
NOTICE: Clean dirt and debris from spark plug recess areas.
3. Spark plugs from cylinder head assemblies.
NOTICE:
Be sure spark plugs thread smoothly into cylinder head assemblies and are fully seated. Cross threading or failing to fully seat spark plugs can cause overheating of spark plugs, exhaust blow-by,
or thread damage. Follow recommended torque specifications carefully. Over or under - tightening
can also cause severe damage to cylinder head assemblies or spark plug.
Check spark plug gap using a wire type gauge before installing. If spark plug gaps are not adjusted
correctly, engine idle quality may be seriously affected. A wire type gauge must be used (as
opposed to a flat feeler type gauge) to insure an accurate reading.
INSTALL OR CONNECT
1. Spark plugs to cylinder head assemblies.
Tighten ^
Spark plugs to 27 Nm (20 lb ft.).
2. Spark plug wire harness assemblies, routed properly as note during removal.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Torque Converter Clutch Solenoid: Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4
Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 5840
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 5841
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > Page 5842
Torque Converter Clutch Solenoid: Service and Repair
REPLACE
1. Raise and support vehicle. 2. Disconnect heated oxygen sensor. 3. Remove catalytic converter
to muffler attaching bolts and nuts. 4. Remove catalytic converter hanger to catalytic converter
bolts. 5. Remove righthand side dampener assembly. 6. Remove nuts holding exhaust pipe to
exhaust manifold. 7. Remove converter and pipe assembly from vehicle. 8. Remove oil pan and oil
filter assembly. 9. Disconnect external wiring harness from transmission pass through connector.
10. Remove accumulator cover attaching bolts. 11. Remove 1-2 accumulator cover, piston and
spring. 12. Disconnect electrical connectors. 13. Remove pressure control solenoid retainer bolt,
then the retainer and solenoid. 14. Remove TCC solenoid retaining bolts. 15. Remove
pass-through electrical connector from transmission case by positioning the small end of power
piston seal protector and diaphragm
retainer installer tool No. J-28458 or equivalent, over the top of the connector, then twist tool to
release the four tabs while at the same time pulling the harness through the case.
16. Remove TCC solenoid with wiring harness from transmission case. 17. Reverse procedure to
install, noting the following:
a. Tighten TCC solenoid retaining bolt to specification. b. Tighten pressure control solenoid
retaining bolt to specification. c. When installing 1-2 accumulator piston to accumulator cover, the
piston legs must face towards the case. d. Tighten accumulator attaching bolts to specification
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 5853
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 5854
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 5855
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment > Page 5861
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment > Page 5862
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment > Page 5863
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Page 5864
Shift Indicator: Description and Operation
DESCRIPTION
This lamp is used on most models equipped with manual transmission.
OPERATION
The Upshift lamp is illuminated to inform the driver of ideal shift points, with improved fuel economy
as the specific objective. When the light is illuminated, the transmission should be shifted to the
next highest gear, if driving conditions permit such an action.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Page 5865
Shift Indicator: Service and Repair
If upshift indicator is not working properly, perform the following test. 1. Disconnect ECM connector
C1. 2. Place ignition switch in run. 3. Measure voltage at terminal A2 of ECM connector. 4. If
battery voltage is present, further ECM diagnosis is necessary. 5. If battery voltage is not present,
repair open circuit in brown/black wire, circuit 456.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Locations > Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Locations > Component Locations > Page 5872
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Locations > Component Locations > Page 5873
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5876
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5877
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5878
Fig.1-Symbols (Part 1 Of 3)
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5879
Fig.2-Symbols (Part 2 Of 3)
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Information > Diagrams > Diagram Information and Instructions > Page 5880
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5881
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5882
Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5883
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5884
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5885
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Transmission Temperature Sensor/Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Temperature Sensor/Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5935
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5936
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5937
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5938
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5939
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5940
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5941
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5942
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5943
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 5944
Transmission Range Switch Assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component
Information > Diagrams > Page 5945
Transmission Temperature Sensor/Switch: Description and Operation
The Transmission Fluid Temperature (TFT) sensor is a thermistor (a device that changes
resistance according to changes in temperature) used to indicate transmission fluid temperature.
High sensor resistance produces high signal input voltage which corresponds to low fluid
temperature. Low sensor resistance produces low signal input voltage which corresponds to high
fluid temperature. The Powertrain Control Module (PCM) uses the TFT sensor signal input to
determine the following:
^ Torque Converter Clutch (TCC) apply and release schedules.
^ Hot mode determination.
^ Shift quality.
The TFT sensor is part of the transmission range fluid pressure switch assembly and is attached to
the control valve body within the transmission. A fault in the Transmission Fluid Temperature (TFT)
sensor circuit will set a DTC 58. 59 or 79.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Customer Interest: > 01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on
Acceleration/DTC's Set
PROM - Programmable Read Only Memory: Customer Interest AIR Pump - Hesitation on
Acceleration/DTC's Set
File In Section: 06 Engine/Propulsion System
Bulletin No.: 01-06-04-011
Date: March, 2001
TECHNICAL
Subject: Water in AIR Pump and/or DTC P0410, P0412, P0415, P0416, P0100, P0101, P0102 or
DTC 48 (AIR System Disable Procedure)
Models: 1995-1996
Buick Roadmaster
1995-1996 Cadillac Fleetwood
1995-1996 Chevrolet Caprice, Impala SS
with 4.3L or 5.7L Engine (VINs W, P - RP0s L99, LT1)
Condition
^ Some customers may comment of a hesitation during heavy/full throttle acceleration.
^ A 1996 vehicle may also set any of the following DTCs:
- P0410
- P0412
- P1415
- P1416
- P0100
- P0101
- P0102
^ A 1995 vehicle may set a DTC 48.
^ There will also be evidence of water in the AIR pump.
Cause
Under high engine speed and load conditions, hot exhaust gasses may leak past the air check
valves. As the exhaust gasses in the air tube cool, water vapors collect into the AIR pump. As the
vehicle is driven, condensation from the AIR pump may come into contact with the Mass Airflow
Sensor through the AIR inlet hose. This condition may cause a hesitation on acceleration and may
also set the DTCs.
Correction
To correct this condition, a Secondary AIR Injection Pump disable procedure has been developed.
(It has been determined that the Secondary AIR Injection system is not required to meet emission
requirements for these vehicles only.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Customer Interest: > 01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on
Acceleration/DTC's Set > Page 5954
1. Locate the relay center (1) and air cleaner box (2).
2. Remove the AIR hose and clamp (1) from the air cleaner box.
3. Insert the plug (2) into the air cleaner box AIR hose inlet (3).
4. Install the AIR hose and clamp (1) to the air cleaner box.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Customer Interest: > 01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on
Acceleration/DTC's Set > Page 5955
5. Remove the cover (1) from the relay center (3).
6. Remove AIR pump relay (2) from the relay center (3).
7. Install the relay cover (1)
8. Install new emission label to radiator support (3).
9. Update vehicle calibration. (1995 4.3 L L99 Caprice, and 1996 vehicles).
Parts Information
Parts are currently available from GMSPO.
Calibration Information
The Calibrations are electronic calibrations and are NOT available from GMSPO. Calibrations will
be available from Techline starting February 2001,
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Customer Interest: > 01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on
Acceleration/DTC's Set > Page 5956
on the TIS 2000 version TIS 2.0/2001 data update or later.
Warranty Information
For vehicles repaired under warranty, use table shown.
1995 4.3 L (RP0 L99) Caprice and 1996 vehicles should also use additional table shown add time
for reprogramming.
DISCLAIMER
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Customer Interest: > 576517A > Jun > 96 > PCM - Chuggle/Surge/Intermittent
DTC 32
PROM - Programmable Read Only Memory: Customer Interest PCM - Chuggle/Surge/Intermittent
DTC 32
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 57-65-17A
Date: June, 1996
Subject: Chuggle or Surge and an Intermittent DTC 32 (Reflash Calibration)
Models: 1994-96 Buick Roadmaster 1994-96 Cadillac Fleetwood 1994-96 Chevrolet Caprice,
Impala SS with 5.7L Engine (VIN P - RPO LT1) and 4L60-E Automatic Transmission
This bulletin is being revised to add the 1996 model year and to update the parts information chart.
Please discard Corporate Bulletin Number 57-65-17 (Section 6E - Engine Fuel and Emission).
Condition
Some owners may comment on a chuggle or a surge condition between 40-65 mph (64-104 kmph).
Also some vehicles may set an intermittent DTC 32 (1994-95 vehicles only).
Correction
Install the proper flash calibration listed from table in Parts Information.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Customer Interest: > 576517A > Jun > 96 > PCM - Chuggle/Surge/Intermittent
DTC 32 > Page 5961
Parts Information
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Labor Time
J6355 Use published labor operation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on Acceleration/DTC's Set
PROM - Programmable Read Only Memory: All Technical Service Bulletins AIR Pump - Hesitation
on Acceleration/DTC's Set
File In Section: 06 Engine/Propulsion System
Bulletin No.: 01-06-04-011
Date: March, 2001
TECHNICAL
Subject: Water in AIR Pump and/or DTC P0410, P0412, P0415, P0416, P0100, P0101, P0102 or
DTC 48 (AIR System Disable Procedure)
Models: 1995-1996
Buick Roadmaster
1995-1996 Cadillac Fleetwood
1995-1996 Chevrolet Caprice, Impala SS
with 4.3L or 5.7L Engine (VINs W, P - RP0s L99, LT1)
Condition
^ Some customers may comment of a hesitation during heavy/full throttle acceleration.
^ A 1996 vehicle may also set any of the following DTCs:
- P0410
- P0412
- P1415
- P1416
- P0100
- P0101
- P0102
^ A 1995 vehicle may set a DTC 48.
^ There will also be evidence of water in the AIR pump.
Cause
Under high engine speed and load conditions, hot exhaust gasses may leak past the air check
valves. As the exhaust gasses in the air tube cool, water vapors collect into the AIR pump. As the
vehicle is driven, condensation from the AIR pump may come into contact with the Mass Airflow
Sensor through the AIR inlet hose. This condition may cause a hesitation on acceleration and may
also set the DTCs.
Correction
To correct this condition, a Secondary AIR Injection Pump disable procedure has been developed.
(It has been determined that the Secondary AIR Injection system is not required to meet emission
requirements for these vehicles only.)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on Acceleration/DTC's Set > Page 5967
1. Locate the relay center (1) and air cleaner box (2).
2. Remove the AIR hose and clamp (1) from the air cleaner box.
3. Insert the plug (2) into the air cleaner box AIR hose inlet (3).
4. Install the AIR hose and clamp (1) to the air cleaner box.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on Acceleration/DTC's Set > Page 5968
5. Remove the cover (1) from the relay center (3).
6. Remove AIR pump relay (2) from the relay center (3).
7. Install the relay cover (1)
8. Install new emission label to radiator support (3).
9. Update vehicle calibration. (1995 4.3 L L99 Caprice, and 1996 vehicles).
Parts Information
Parts are currently available from GMSPO.
Calibration Information
The Calibrations are electronic calibrations and are NOT available from GMSPO. Calibrations will
be available from Techline starting February 2001,
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
01-06-04-011 > Mar > 01 > AIR Pump - Hesitation on Acceleration/DTC's Set > Page 5969
on the TIS 2000 version TIS 2.0/2001 data update or later.
Warranty Information
For vehicles repaired under warranty, use table shown.
1995 4.3 L (RP0 L99) Caprice and 1996 vehicles should also use additional table shown add time
for reprogramming.
DISCLAIMER
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
99-06-04-053 > Nov > 99 > PROM - Powertrain Control Module Reprogramming
PROM - Programmable Read Only Memory: All Technical Service Bulletins PROM - Powertrain
Control Module Reprogramming
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 99-06-04-053
Date: November, 1999
INFORMATION
Subject: Powertrain Control Module (PCM) Reprogramming (Do Not Reprogram Using the Same
Download Files as Those Already Present in The Control Module)
Models: 1990-2000 Passenger Cars and Trucks with Reprogrammable PCM
It is strongly recommended to NOT reinstall the same software and/or calibration download file(s)
into the powertrain control module as those that are already present in the PCM. There is no
technical reason that the download files inside the PCM would ever become corrupted after the
control module had previously been successfully programmed. A P0601 (Control Module Read
Only Memory) Diagnostic Trouble Code would set in memory and the MIL would be illuminated if
the controller memory became corrupted.
The Techline Information System 2000 (TIS 2000) PC, combined with vehicle information gained
through the Tech 2, can determine when an attempt to reprogram a PCM using the same download
files (as those already in the control module) is being requested. If this is attempted, the TIS 2000
PC currently displays the following message:
Notice:
THE CALIBRATION SELECTED IS THE CURRENT CALIBRATION IN THE CONTROL MODULE.
PROGRAMMING WITH THE SAME DOWNLOAD FILES IS NOT AN EFFECTIVE REPAIR.
SELECT ( YES ) TO CONTINUE PROGRAMMING THE CONTROL MODULE,OR ( NO ) TO
CANCEL.
Effective in the first quarter of 2000, the TIS 2000 PC will indicate:
Important:
THE CALIBRATION SELECTED IS ALREADY THE CURRENT CALIBRATION IN THE CONTROL
MODULE. REPROGRAMMING WITH THE SAME DOWNLOAD FILE IS NOT ALLOWED.
Certain learned values, such as: (but not limited to)
^ fuel trim (previously known as block learn memory),
^ IAC learned position in various park/neutral and air conditioning on/off combinations,
^ certain OBDII diagnostic thresholds,
^ automatic transmission shift adapts
will revert back to their unlearned starting point values after a reprogramming event occurs.
It is feasible that the engine or transmission might temporarily operate differently after a
reprogramming event, until these values are re-learned. Relearning occurs while operating the
vehicle through normal driving routines. If the same download files are simply reinstalled, any
changes noticed in engine operation will likely disappear in a short amount of time and/or driving
distance.
Reprogramming the control module with the same download files that already exist in the module
will only accomplish a warranty claim for a non-effective repair, and a likely comeback.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter
PROM - Programmable Read Only Memory: All Technical Service Bulletins PROM - Reprogram
Using Off Board Program Adapter
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 73-65-13
Date: March, 1997
INFORMATION
Subject: Reprogramming Capability using the Off Board Programming Adapter
Models: 1993-97 Passenger Cars and Trucks (Applicable Reprogrammable Vehicles)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5978
The General Motors vehicles contain Electronically Reprogrammable Devices (i.e. PCM, VCM,
ECM). These vehicles cannot be programmed through PROM replacement, however service
programming capability is available through the Tech 1/1A, Tech 2 and Techline terminals via
direct or remote programming.
The Environmental Protection Agency (EPA) has requested that all new vehicle manufacturers
ensure their dealers/retailers are aware that they are responsible for providing customers access to
reprogramming services at a reasonable cost and in a timely manner.
Although programming of controllers has become a common service practice at GM
dealers/retailers, the EPA has received reports from consumers and the aftermarket repair industry
that they were unable to purchase a new (programmed) Electronically Reprogrammable Device
(ERD) over-the-counter. As a result, on August 1, 1995, the Federal Government issued a
regulation requiring all manufacturers to make available reprogramming to the independent
aftermarket by December 1, 1997.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5979
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5980
Today, the Off Board Programming Adapter (OBPA) is used to reprogram ERD's sold
over-the-counter. For all practical purposes, the OBPA takes the place of the vehicle when the
vehicle is not available.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5981
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5982
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5983
The list of dealerships/retailers currently own the OBPA (see Attachments 1 - 3). These locations
are equipped to provide over-the-counter preprogrammed ERD's. The hardware required to
perform reprogramming in addition to the OBPA is a Techline terminal, Tech 1/1A and associated
cables and adapters. THE TECH 2 SHOULD NOT BE USED WITH THE OBPA AT THIS TIME
BECAUSE OF INADEQUATE OBPA GROUNDING.
The current OBPA can support reprogramming on all late model General Motor's vehicles except:
^ Premium V-8's
^ 1996 Diesel Truck
^ Cadillac Catera
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 5984
^ All 1997 programmable vehicles (requires use of the Tech 2)
A modification to the OBPA is being offered by Kent-Moore to support these additional vehicles and
to allow reprogramming using the Tech 2. The revisions to the OBPA for the Tech 2 is very
important as the Tech 2 is the only tool used for service programming for 1997 and future vehicles.
To have the modifications performed, contact Kent-Moore at (800) 345-2233. The revisions (part
number J 41207 REV-C) are free of charge for GM dealerships/retailers.
A dealership/retailer can purchase the OBPA by contacting Kent-Moore (part number J 41207-C).
Support on how to use the OBPA is provided by the Techline Customer Support Center (TCSC) at
(800) 828-6860 (English) or (800) 503-3222 (French).
If you need to purchase an OBPA and/or cable, contact Kent-Moore at (800) 345-2233. The OBPA
retails for $695.00 (includes all revisions 1-4) under part number J 41207-C.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
576517A > Jun > 96 > PCM - Chuggle/Surge/Intermittent DTC 32
PROM - Programmable Read Only Memory: All Technical Service Bulletins PCM Chuggle/Surge/Intermittent DTC 32
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 57-65-17A
Date: June, 1996
Subject: Chuggle or Surge and an Intermittent DTC 32 (Reflash Calibration)
Models: 1994-96 Buick Roadmaster 1994-96 Cadillac Fleetwood 1994-96 Chevrolet Caprice,
Impala SS with 5.7L Engine (VIN P - RPO LT1) and 4L60-E Automatic Transmission
This bulletin is being revised to add the 1996 model year and to update the parts information chart.
Please discard Corporate Bulletin Number 57-65-17 (Section 6E - Engine Fuel and Emission).
Condition
Some owners may comment on a chuggle or a surge condition between 40-65 mph (64-104 kmph).
Also some vehicles may set an intermittent DTC 32 (1994-95 vehicles only).
Correction
Install the proper flash calibration listed from table in Parts Information.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
576517A > Jun > 96 > PCM - Chuggle/Surge/Intermittent DTC 32 > Page 5989
Parts Information
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation Labor Time
J6355 Use published labor operation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming
PROM - Programmable Read Only Memory: All Technical Service Bulletins SPS/FLASH EPROM Programming
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 53-65-08
Date: January, 1996
INFORMATION
Subject: SPS/FLASH EPROM Programming
Models: 1993-96 Passenger Cars and Trucks Applicable Reprogrammable Vehicles
This bulletin is being issued to assist technicians in reprogramming vehicles and should be used in
conjunction with instructions provided on your Techline Terminal and in your Techline Terminal
User's Manual.
THE TECHLINE TERMINAL (T-20, T-50, T-60) HAS BEEN ABLE TO DO 1996 VEHICLE
PROGRAMMING THROUGH THE DIRECT METHOD SINCE 1996 VEHICLES HAVE BEEN
AVAILABLE IN THE DEALERSHIPS/RETAIL FACILITIES. THE TECHLINE CD-ROM TITLED
DISC 13 CONTAINS THE SOFTWARE NEEDED TO PROGRAM ALL 1996 VEHICLES WITH A
TECH 1 (REMOTE PROGRAMMING METHOD).
SPS Tips
1. BATTERY VOLTAGE SHOULD BE CHECKED. A FULLY CHARGED BATTERY IS
NECESSARY BEFORE REPROGRAMMING TAKES PLACE. THE VEHICLE BATTERY SHOULD
NOT BE CONNECTED TO A BATTERY CHARGER DURING A PROGRAMMING EVENT
INCORRECT VOLTAGE COULD CAUSE PROGRAMMING AND/OR CONTROL MODULE
FAILURE. During programming, the control module depends on the battery as its sole source of
power. Also during programming, the vehicle's components (i.e. blower motor) are set to a default
mode which may be turned on, placing additional draw on the vehicle's battery. If the voltage goes
outside the specified range (11 to 14 volts) the controllers and the Techline equipment will stop
communicating. If this happens, it could cause the control module to become inoperable and
require replacement.
2. CHECK THE INTEGRITY OF THE TECH 1 CABLES, MAKE SURE THEY ARE NOT FRAYED,
BROKEN OR TWISTED. Loss of communication for any reason will require additional time in
completing the reprogramming event.
3. IF USING A TECH 1, YOUR MASS STORAGE CARTRIDGE (MSC) MUST BE UPDATED TO
REFLECT THE MOST CURRENT UPDATE OFFERED ON THE TECHLINE CD-ROM. DISC 13,
1995 WAS THE FIRST CD-ROM THAT HAD REMOTE PROGRAMMING SUPPORT If your MSC
is not updated to reflect the current software version on the Techline Terminal, in some situations
the software will not be capable of interpreting the information that is requested from the vehicle.
4. T-100 TERMINALS (CAMS) ARE NOT CAPABLE OF PROGRAMMING OBD II VEHICLES
THROUGH THE DIRECT METHOD. A TECH 1 MUST BE USED (REMOTE METHOD) WHEN
REPROGRAMMING WITH A T-100. The T-100 terminals communicate with vehicles through a
DLC (ALDL) card and cable found within the T-100's computer. The DLC (ALDL) card is not
capable of communicating at the new baud rate used with OBD II.
5. PROGRAMMING IS NOT NEEDED IF THE CURRENT CALIBRATION IS THE SAME AS THE
SELECTED CALIBRATION.
6. IF PROGRAMMING A NEW CONTROL MODULE, YOU MUST REQUEST INFORMATION
FROM THE NEW CONTROL MODULE. The security information that is needed for a control
module to be programmed is stored in the new control module. The security information must be
requested from the control module to be programmed. At that point, the control module can be
successfully programmed. This requesting of security information takes place in both the direct and
remote methods. The request is automatic when using the direct method. Looking at the calibration
stored in the old controller may be helpful in selecting the calibration from the CD-ROM for the new
controller.
7. WHEN PROGRAMMING OBD II VEHICLES WITH A TECH 1 (REMOTE PROGRAMMING
METHOD), A VEHICLE INTERFACE MODULE (VIM) IS REQUIRED. The VIM allows the Tech 1
to communicate with the OBD II vehicles. The VIM is necessary for all other Tech 1 diagnostics on
OBD II vehicles. VIMs are no longer on backorder. If you are interested in obtaining additional
VIMs, call 1-800-GM-TOOLS and ask for VIM kit part number 7000041.
8. DISCONNECT THE TECH I AND VIM FROM THE VEHICLE BETWEEN RETRIEVING DATA
AND PROGRAMMING THE VEHICLE. If the VIM remains powered up after data is requested, a
communication problem may result when the reprogramming function is performed.
9. WHEN CONNECTING THE TECH 1 TO A TECHLINE TERMINAL (EXCEPT T-100 CAMS),
ALWAYS CONNECT THE FLAT GRAY R5232 CABLE FIRST AND THEN THE POWER
ADAPTER. FAILURE TO DO SO COULD RESULT IN A LOSS OF INFORMATION
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming > Page 5994
STORED ON THE TECH 1. When power is turned on to the Tech 1, it looks for the RS232
connection. If it does not see the connection, the Tech 1 in some cases, will erase the information
stored for download.
10. DO NOT DISCONTINUE OR INTERRUPT THE PROGRAM LOADING PROCESS TO THE
VEHICLE. This will result in a programming error and could prevent the Electronic Control Module
(ECM) from functioning properly.
11. AFTER PROGRAMMING IS COMPLETE, PRESS "EXIT". MAKE SURE THE KEY IS CYCLED
OFF FOR APPROXIMATELY 10 SECONDS THEN BACK ON. Some vehicles will lose component
settings (PMC/IAC Valve). Cycling the key off two times (Off for 30 seconds, On for 10 then repeat
a second time) will allow for resetting of the components. Start the vehicle to ensure programming
was successful.
FOR CADILLAC VEHICLES ONLY a. DUE TO OTHER MODULES ON THE DATA LINE TRYING TO COMMUNICATE WITH THE
ECM DURING PROGRAMMING, SOME COMMUNICATION CODES MAY BE SET After
programming is complete, clear any codes and verify they do not reset.
b. TO HELP MINIMIZE BATTERY DRAW DURING ECM PROGRAMMING, DISCONNECT THE
BLOWER MOTOR (AT THE CONNECTOR, NOT THE FUSE) PRIOR TO PROGRAMMING. When
programming is complete, reconnect the blower motor.
12. 1997 VEHICLES REQUIRE REPROGRAMMING BE DONE USING A TECH 2. OBD II vehicle
calibration size and complexity will require more memory than the Tech 1 has available. Tech 2 will
be an essential tool in the first quarter of 1996 containing limited 1996 applications and updates.
13. STG HAS ISSUED BULLETINS (# 53-65-04 and # 53-65-05 - (SEE CHART EXCERPTED
FROM 53-65-05 FOR USE AS A QUICK REFERENCE GUIDE), DEVELOPED QUICK
REFERENCE GUIDES (P/N SPSCARD-1 AVAILABLE THROUGH YOUR LOCAL GM TRAINING
CENTER), PRODUCED CPT VIDEOS (CPT # 56010.00-B), HAD PULSAT BROADCASTS, AND
OFFERS GM TRAINING CENTER CLASSROOM COURSES. As you work through
reprogramming, keep the above-mentioned material in mind as resources to assist you if difficulty
is encountered. As always, the Techline Customer Support Center (1-800-828-6860 English,
1-800-503-3222 French) is always available to assist the technician with any situation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming > Page 5995
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming > Page 5996
SPS/EEPROM Programming
1993 to current Reprogrammable Vehicles
Note: If programming a new control module you must request info from the new control module
first. Battery voltage should be checked and at full charge before reprogramming takes place.
System to be programmed should NOT be connected to a battery charger. Incorrect voltage could
cause programming and/or control module failure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536505 > Oct > 95 > SPS/EEPROM - Programming Chart
PROM - Programmable Read Only Memory: All Technical Service Bulletins SPS/EEPROM Programming Chart
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 53-65-05
Date: October, 1995
Subject: Chart to Assist Technician with SPS/EEPROM Programming
Models: 1995-96 Passenger Cars and Trucks
This bulletin is being issued to assist technicians with the reprogramming of vehicles. The following
chart was developed to be used by technicians that are familiar with the Techline terminals, Tech 1
and all of its adapters:
IMPORTANT
If programming a new control module, you must request information from the new control module
first.
Battery voltage must be between 11 and 14 volts. System to be programmed should NOT be
connected to a battery charger. Incorrect voltage could cause programming and/or control module
failure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536505 > Oct > 95 > SPS/EEPROM - Programming Chart > Page 6001
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for PROM - Programmable Read Only Memory: >
536505 > Oct > 95 > SPS/EEPROM - Programming Chart > Page 6002
Programming Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
99-06-04-053 > Nov > 99 > PROM - Powertrain Control Module Reprogramming
PROM - Programmable Read Only Memory: All Technical Service Bulletins PROM - Powertrain
Control Module Reprogramming
File In Section: 06 - Engine/Propulsion System
Bulletin No.: 99-06-04-053
Date: November, 1999
INFORMATION
Subject: Powertrain Control Module (PCM) Reprogramming (Do Not Reprogram Using the Same
Download Files as Those Already Present in The Control Module)
Models: 1990-2000 Passenger Cars and Trucks with Reprogrammable PCM
It is strongly recommended to NOT reinstall the same software and/or calibration download file(s)
into the powertrain control module as those that are already present in the PCM. There is no
technical reason that the download files inside the PCM would ever become corrupted after the
control module had previously been successfully programmed. A P0601 (Control Module Read
Only Memory) Diagnostic Trouble Code would set in memory and the MIL would be illuminated if
the controller memory became corrupted.
The Techline Information System 2000 (TIS 2000) PC, combined with vehicle information gained
through the Tech 2, can determine when an attempt to reprogram a PCM using the same download
files (as those already in the control module) is being requested. If this is attempted, the TIS 2000
PC currently displays the following message:
Notice:
THE CALIBRATION SELECTED IS THE CURRENT CALIBRATION IN THE CONTROL MODULE.
PROGRAMMING WITH THE SAME DOWNLOAD FILES IS NOT AN EFFECTIVE REPAIR.
SELECT ( YES ) TO CONTINUE PROGRAMMING THE CONTROL MODULE,OR ( NO ) TO
CANCEL.
Effective in the first quarter of 2000, the TIS 2000 PC will indicate:
Important:
THE CALIBRATION SELECTED IS ALREADY THE CURRENT CALIBRATION IN THE CONTROL
MODULE. REPROGRAMMING WITH THE SAME DOWNLOAD FILE IS NOT ALLOWED.
Certain learned values, such as: (but not limited to)
^ fuel trim (previously known as block learn memory),
^ IAC learned position in various park/neutral and air conditioning on/off combinations,
^ certain OBDII diagnostic thresholds,
^ automatic transmission shift adapts
will revert back to their unlearned starting point values after a reprogramming event occurs.
It is feasible that the engine or transmission might temporarily operate differently after a
reprogramming event, until these values are re-learned. Relearning occurs while operating the
vehicle through normal driving routines. If the same download files are simply reinstalled, any
changes noticed in engine operation will likely disappear in a short amount of time and/or driving
distance.
Reprogramming the control module with the same download files that already exist in the module
will only accomplish a warranty claim for a non-effective repair, and a likely comeback.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter
PROM - Programmable Read Only Memory: All Technical Service Bulletins PROM - Reprogram
Using Off Board Program Adapter
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 73-65-13
Date: March, 1997
INFORMATION
Subject: Reprogramming Capability using the Off Board Programming Adapter
Models: 1993-97 Passenger Cars and Trucks (Applicable Reprogrammable Vehicles)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6012
The General Motors vehicles contain Electronically Reprogrammable Devices (i.e. PCM, VCM,
ECM). These vehicles cannot be programmed through PROM replacement, however service
programming capability is available through the Tech 1/1A, Tech 2 and Techline terminals via
direct or remote programming.
The Environmental Protection Agency (EPA) has requested that all new vehicle manufacturers
ensure their dealers/retailers are aware that they are responsible for providing customers access to
reprogramming services at a reasonable cost and in a timely manner.
Although programming of controllers has become a common service practice at GM
dealers/retailers, the EPA has received reports from consumers and the aftermarket repair industry
that they were unable to purchase a new (programmed) Electronically Reprogrammable Device
(ERD) over-the-counter. As a result, on August 1, 1995, the Federal Government issued a
regulation requiring all manufacturers to make available reprogramming to the independent
aftermarket by December 1, 1997.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6013
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6014
Today, the Off Board Programming Adapter (OBPA) is used to reprogram ERD's sold
over-the-counter. For all practical purposes, the OBPA takes the place of the vehicle when the
vehicle is not available.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6015
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6016
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6017
The list of dealerships/retailers currently own the OBPA (see Attachments 1 - 3). These locations
are equipped to provide over-the-counter preprogrammed ERD's. The hardware required to
perform reprogramming in addition to the OBPA is a Techline terminal, Tech 1/1A and associated
cables and adapters. THE TECH 2 SHOULD NOT BE USED WITH THE OBPA AT THIS TIME
BECAUSE OF INADEQUATE OBPA GROUNDING.
The current OBPA can support reprogramming on all late model General Motor's vehicles except:
^ Premium V-8's
^ 1996 Diesel Truck
^ Cadillac Catera
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
736513 > Mar > 97 > PROM - Reprogram Using Off Board Program Adapter > Page 6018
^ All 1997 programmable vehicles (requires use of the Tech 2)
A modification to the OBPA is being offered by Kent-Moore to support these additional vehicles and
to allow reprogramming using the Tech 2. The revisions to the OBPA for the Tech 2 is very
important as the Tech 2 is the only tool used for service programming for 1997 and future vehicles.
To have the modifications performed, contact Kent-Moore at (800) 345-2233. The revisions (part
number J 41207 REV-C) are free of charge for GM dealerships/retailers.
A dealership/retailer can purchase the OBPA by contacting Kent-Moore (part number J 41207-C).
Support on how to use the OBPA is provided by the Techline Customer Support Center (TCSC) at
(800) 828-6860 (English) or (800) 503-3222 (French).
If you need to purchase an OBPA and/or cable, contact Kent-Moore at (800) 345-2233. The OBPA
retails for $695.00 (includes all revisions 1-4) under part number J 41207-C.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming
PROM - Programmable Read Only Memory: All Technical Service Bulletins SPS/FLASH EPROM Programming
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 53-65-08
Date: January, 1996
INFORMATION
Subject: SPS/FLASH EPROM Programming
Models: 1993-96 Passenger Cars and Trucks Applicable Reprogrammable Vehicles
This bulletin is being issued to assist technicians in reprogramming vehicles and should be used in
conjunction with instructions provided on your Techline Terminal and in your Techline Terminal
User's Manual.
THE TECHLINE TERMINAL (T-20, T-50, T-60) HAS BEEN ABLE TO DO 1996 VEHICLE
PROGRAMMING THROUGH THE DIRECT METHOD SINCE 1996 VEHICLES HAVE BEEN
AVAILABLE IN THE DEALERSHIPS/RETAIL FACILITIES. THE TECHLINE CD-ROM TITLED
DISC 13 CONTAINS THE SOFTWARE NEEDED TO PROGRAM ALL 1996 VEHICLES WITH A
TECH 1 (REMOTE PROGRAMMING METHOD).
SPS Tips
1. BATTERY VOLTAGE SHOULD BE CHECKED. A FULLY CHARGED BATTERY IS
NECESSARY BEFORE REPROGRAMMING TAKES PLACE. THE VEHICLE BATTERY SHOULD
NOT BE CONNECTED TO A BATTERY CHARGER DURING A PROGRAMMING EVENT
INCORRECT VOLTAGE COULD CAUSE PROGRAMMING AND/OR CONTROL MODULE
FAILURE. During programming, the control module depends on the battery as its sole source of
power. Also during programming, the vehicle's components (i.e. blower motor) are set to a default
mode which may be turned on, placing additional draw on the vehicle's battery. If the voltage goes
outside the specified range (11 to 14 volts) the controllers and the Techline equipment will stop
communicating. If this happens, it could cause the control module to become inoperable and
require replacement.
2. CHECK THE INTEGRITY OF THE TECH 1 CABLES, MAKE SURE THEY ARE NOT FRAYED,
BROKEN OR TWISTED. Loss of communication for any reason will require additional time in
completing the reprogramming event.
3. IF USING A TECH 1, YOUR MASS STORAGE CARTRIDGE (MSC) MUST BE UPDATED TO
REFLECT THE MOST CURRENT UPDATE OFFERED ON THE TECHLINE CD-ROM. DISC 13,
1995 WAS THE FIRST CD-ROM THAT HAD REMOTE PROGRAMMING SUPPORT If your MSC
is not updated to reflect the current software version on the Techline Terminal, in some situations
the software will not be capable of interpreting the information that is requested from the vehicle.
4. T-100 TERMINALS (CAMS) ARE NOT CAPABLE OF PROGRAMMING OBD II VEHICLES
THROUGH THE DIRECT METHOD. A TECH 1 MUST BE USED (REMOTE METHOD) WHEN
REPROGRAMMING WITH A T-100. The T-100 terminals communicate with vehicles through a
DLC (ALDL) card and cable found within the T-100's computer. The DLC (ALDL) card is not
capable of communicating at the new baud rate used with OBD II.
5. PROGRAMMING IS NOT NEEDED IF THE CURRENT CALIBRATION IS THE SAME AS THE
SELECTED CALIBRATION.
6. IF PROGRAMMING A NEW CONTROL MODULE, YOU MUST REQUEST INFORMATION
FROM THE NEW CONTROL MODULE. The security information that is needed for a control
module to be programmed is stored in the new control module. The security information must be
requested from the control module to be programmed. At that point, the control module can be
successfully programmed. This requesting of security information takes place in both the direct and
remote methods. The request is automatic when using the direct method. Looking at the calibration
stored in the old controller may be helpful in selecting the calibration from the CD-ROM for the new
controller.
7. WHEN PROGRAMMING OBD II VEHICLES WITH A TECH 1 (REMOTE PROGRAMMING
METHOD), A VEHICLE INTERFACE MODULE (VIM) IS REQUIRED. The VIM allows the Tech 1
to communicate with the OBD II vehicles. The VIM is necessary for all other Tech 1 diagnostics on
OBD II vehicles. VIMs are no longer on backorder. If you are interested in obtaining additional
VIMs, call 1-800-GM-TOOLS and ask for VIM kit part number 7000041.
8. DISCONNECT THE TECH I AND VIM FROM THE VEHICLE BETWEEN RETRIEVING DATA
AND PROGRAMMING THE VEHICLE. If the VIM remains powered up after data is requested, a
communication problem may result when the reprogramming function is performed.
9. WHEN CONNECTING THE TECH 1 TO A TECHLINE TERMINAL (EXCEPT T-100 CAMS),
ALWAYS CONNECT THE FLAT GRAY R5232 CABLE FIRST AND THEN THE POWER
ADAPTER. FAILURE TO DO SO COULD RESULT IN A LOSS OF INFORMATION
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming > Page 6023
STORED ON THE TECH 1. When power is turned on to the Tech 1, it looks for the RS232
connection. If it does not see the connection, the Tech 1 in some cases, will erase the information
stored for download.
10. DO NOT DISCONTINUE OR INTERRUPT THE PROGRAM LOADING PROCESS TO THE
VEHICLE. This will result in a programming error and could prevent the Electronic Control Module
(ECM) from functioning properly.
11. AFTER PROGRAMMING IS COMPLETE, PRESS "EXIT". MAKE SURE THE KEY IS CYCLED
OFF FOR APPROXIMATELY 10 SECONDS THEN BACK ON. Some vehicles will lose component
settings (PMC/IAC Valve). Cycling the key off two times (Off for 30 seconds, On for 10 then repeat
a second time) will allow for resetting of the components. Start the vehicle to ensure programming
was successful.
FOR CADILLAC VEHICLES ONLY a. DUE TO OTHER MODULES ON THE DATA LINE TRYING TO COMMUNICATE WITH THE
ECM DURING PROGRAMMING, SOME COMMUNICATION CODES MAY BE SET After
programming is complete, clear any codes and verify they do not reset.
b. TO HELP MINIMIZE BATTERY DRAW DURING ECM PROGRAMMING, DISCONNECT THE
BLOWER MOTOR (AT THE CONNECTOR, NOT THE FUSE) PRIOR TO PROGRAMMING. When
programming is complete, reconnect the blower motor.
12. 1997 VEHICLES REQUIRE REPROGRAMMING BE DONE USING A TECH 2. OBD II vehicle
calibration size and complexity will require more memory than the Tech 1 has available. Tech 2 will
be an essential tool in the first quarter of 1996 containing limited 1996 applications and updates.
13. STG HAS ISSUED BULLETINS (# 53-65-04 and # 53-65-05 - (SEE CHART EXCERPTED
FROM 53-65-05 FOR USE AS A QUICK REFERENCE GUIDE), DEVELOPED QUICK
REFERENCE GUIDES (P/N SPSCARD-1 AVAILABLE THROUGH YOUR LOCAL GM TRAINING
CENTER), PRODUCED CPT VIDEOS (CPT # 56010.00-B), HAD PULSAT BROADCASTS, AND
OFFERS GM TRAINING CENTER CLASSROOM COURSES. As you work through
reprogramming, keep the above-mentioned material in mind as resources to assist you if difficulty
is encountered. As always, the Techline Customer Support Center (1-800-828-6860 English,
1-800-503-3222 French) is always available to assist the technician with any situation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming > Page 6024
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536508 > Jan > 96 > SPS/FLASH EPROM - Programming > Page 6025
SPS/EEPROM Programming
1993 to current Reprogrammable Vehicles
Note: If programming a new control module you must request info from the new control module
first. Battery voltage should be checked and at full charge before reprogramming takes place.
System to be programmed should NOT be connected to a battery charger. Incorrect voltage could
cause programming and/or control module failure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536505 > Oct > 95 > SPS/EEPROM - Programming Chart
PROM - Programmable Read Only Memory: All Technical Service Bulletins SPS/EEPROM Programming Chart
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 53-65-05
Date: October, 1995
Subject: Chart to Assist Technician with SPS/EEPROM Programming
Models: 1995-96 Passenger Cars and Trucks
This bulletin is being issued to assist technicians with the reprogramming of vehicles. The following
chart was developed to be used by technicians that are familiar with the Techline terminals, Tech 1
and all of its adapters:
IMPORTANT
If programming a new control module, you must request information from the new control module
first.
Battery voltage must be between 11 and 14 volts. System to be programmed should NOT be
connected to a battery charger. Incorrect voltage could cause programming and/or control module
failure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536505 > Oct > 95 > SPS/EEPROM - Programming Chart > Page 6030
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > All Other Service Bulletins for PROM - Programmable Read Only Memory: >
536505 > Oct > 95 > SPS/EEPROM - Programming Chart > Page 6031
Programming Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Technical Service Bulletins > Page 6032
PROM - Programmable Read Only Memory: Service Precautions
A PROM is a sensitive electronic part and must be handled with care. If the connector terminals
(pins) on the bottom of the PROM are exposed, avoid touching them. Pins can be broken easily,
and the PROM can be damaged by static electric discharge. Follow these guidelines when
replacing a PROM:
^ Disconnect the battery ground cable before removing a PROM. Reconnect the cable after the
new PROM is installed.
^ DO NOT try to remove a PROM from its plastic PROM carrier.
^ Note the direction in which the original PROM and its carrier were installed in the ECM, and
install the replacement PROM in the same direction. Most PROM's are marked with a notch at one
end for orientation. Many PROM's can be installed in a reversed direction, which will destroy the
PROM when power is applied.
CAUTION: A PROM can be damaged by static electric discharge. Avoid damage as follows:
^ DO NOT remove a PROM from its packing material until you are ready to install it. DO NOT hold
a PROM by its pins.
^ Before entering a vehicle to remove or replace a PROM, touch an exposed metal part of the
vehicle to discharge any static charge from your body or use anti-static wrist straps.
^ Avoid sliding across upholstery or carpeting when removing or installing a PROM. If this is not
possible, touch an exposed metal part of the vehicle with your free hand before removing a PROM
or installing a new one in its socket in the ECM.
^ When available, use an antistatic grounding strap attached to your wrist and clipped to a metal
part of the vehicle body to prevent static charges from accumulating. Antistatic, conductive
floormats are also available.
^ For some vehicles, it may be desirable to remove the ECM when replacing the PROM.
^ NOTE: See POWERTRAIN MANAGEMENT / SERVICE PRECAUTIONS / VEHICLE DAMAGE
WARNINGS / ELECTRICAL PRECAUTIONS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index
PROM - Programmable Read Only Memory: Application and ID Introducing the GM PROM Cross
Reference Index
This PROM cross reference index provides tables that let you use a PROM identification (ID) code
to identify the PROM installed in the engine control module (ECM) on most GM vehicles. The code
can be either - or both - the internal "scan ID" code or the external PROM code. From the PROM
identification, you can find the part number of the PROM and trace the PROM history to determine
if any revised PROM's have been issued to supersede the one in the vehicle.
The PROM history for a specific vehicle lists a succession of superseding PROM's ending with the
most recent PROM released as a service part for the vehicle. PROM's that were released as
service parts and explained in a technical service bulletin (TSB) are listed with a description of why
the PROM was issued. In most cases, the applicable TSB also is referenced.
This index lists ECM PROM's for the 1980-95 vehicles. It does not contain ID codes and part
numbers for all PROM's used in all GM vehicles. NOTE: GM flash PROM's (EEPROM's) can only
be updated at GM Dealerships with factory-supplied equipment. These cars will not display a
PROM ID.
By following the steps outlined below, you can use the PROM index to determine if the problem
you are diagnosing can possibly be corrected by installing a revised PROM. The PROM index
tables are organized by model year, engine displacement, and engine code (the eighth digit of the
Vehicle Identification Number). The table columns are arranged as shown below:
Example of Table Column Arrangement
SCAN PROM PROM PART SUPERSEDING TSB REFERENCE
ID CODE (BCC) NUMBER ID PART NUMBER NUMBER
(1) (2) (3) (4) (5)
..............................................................................................................................................................
........................................................................
9461 8958 AMU 16058955R 8290 01228290 86194
Column 1, SCAN ID:
The scan ID is the internal PROM identification number transmitted on the ECM data stream and
displayed by the scanner as PROM ID. The PROM records for each year and engine are listed
numerically by this scan ID.
Column 2, PROM CODE:
These are the numbers and letters marked on the top of the PROM itself. The numbers are often
referred to as the "external PROM ID." The letters are often called the "broadcast code." Together
they are the external PROM code.
Column 3, PROM P/N:
This is the GM part number for the PROM identified by the codes in columns 1 and 2.
Column 4, SUPERSEDING ID PROM PART NUMBER:
Use the superseding scan ID to locate the newer PROM in the table. If the scan ID for the
superseding PROM is not known, the PROM broadcast code is listed here. If the PROM is
superseded by a newer PROM, that part number is listed here.
Column 5, TSB REFERENCE NUMBER
The TSB NUMBER column identifies the original TSB that released this PROM for service.
Whenever possible you should refer to the TSB for additional information before changing a
PROM. The bulletin may list other parts that must be installed when the PROM is changed, or it
may provide additional troubleshooting information. To find a TSB, see Reading Technical Service
Bulletins. See: Reading Technical Service Bulletins This will display all the TSB's for that particular
vehicle.
EXPANDED FOOTNOTES Here you will find SUPERSEDING SCAN ID, PROM PART NUMBERS,
symptoms and additional parts that need to be replaced when servicing the PROM.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6035
PROM - Programmable Read Only Memory: Application and ID Additional PROM Information
New ECM PROMs for GM vehicles may be released for service at any time. The information in this
system is accurate to the best of the publisher's knowledge and the publication date of the disk.
Before ordering a PROM, consult with a GM parts and service dealer to verify the latest part
number information. Scanner PROM ID information for earlier-model vehicles (1980-83) is less
complete than for later models. To accurately identify PROM's in earlier vehicles, it may be
necessary to check the external PROM code marked on the PROM.
General Motors has often recommended that dealership technicians check the PROM history of a
vehicle and install the most recent PROM revision before performing other diagnostic operations.
Each succeeding PROM revision for a specific vehicle includes all previous revisions. Therefore,
whenever you consider changing a PROM, review the entire PROM history to see if any revision
covered the current driveability problem. Installing the most recent PROM revision may be
impractical however for an independent service facility, particularly if the latest PROM revision does
not address the specific driveability problem of the vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6036
PROM - Programmable Read Only Memory: Application and ID PROM/MEMCAL Identification
Marks
File In Section: 6E - Engine Fuel & Emission
Bulletin No.: 44-65-01
Date: October, 1994
Subject: New PROM/MEMCAL Identification Markings
Models: 1995 and Prior Passenger Cars and Trucks
Note:
For the purposes of this document, the terms PROM and MEMCAL will be used interchangeably.
To simplify identification of service PROMs. a new external marking format will be implemented.
Parts manufactured after Sept. 1994 will feature these new markings. This change will place the full
8-digit service part number on the PROM, in place of the old 4-digit "EXTERNAL ID" number. In the
past, parts and service personnel could not identify a PROM without using a cross-reference table
that matched external IDs and service numbers. In the future, the cross-reference table will not be
required for PROMs; parts will be ordered directly from the number appearing on the PROM.
However, the label will retain the broadcast code alpha characters to allow continued use of
cross-reference charts, if so desired.
Old Marking Format:
New Marking Format:
^ Ordering the above PROM from the old marking format would require using a cross-reference
chart to determine a service part number, based on the BROAD CAST CODE and EXTERNAL ID
NUMBERS.
^ To order from the new format, simply combine the 2nd and 3rd lines to form an 8-digit part
number that can be directly ordered from SPO (number 16134624 in the above example).
As these changes are phased into the parts inventory, it should be noted that dealers will continue
to see parts with both formats for some time in the future. This is because:
^ Millions of vehicles have already been built with the old format.
^ SPO has existing stock of MEMCALs and PROMs with the old format.
^ PROMS with 7-digit part numbers (representing less than 10% of current part numbers) will
continue to use the old format. The 7-digit part numbers are easily identified because they always
begin with "122xxxx".
Due to manufacturing processes, more than one 8-digit part number may appear on a MEMCAL. In
this event, service personnel should use the label on the exterior cover of the MEMCAL assembly.
To avoid confusion, only the service label will include the BROAD CAST CODE, consisting of letter
characters (I.E., ARCL).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6037
CHANGES TO MEMCAL/PROM LABELING FORMATS
^ MEMCALs may use either INK-JET or ADHESIVE labels, as shown.
^ PROMs will always use ADHESIVE labels with the same format as shown for MEMCALs. These
changes will become effective on parts manufactured after 10/94.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6038
PROM - Programmable Read Only Memory: Application and ID Reading Technical Service
Bulletins
Always read any Technical Service Bulletins (TSB's) referenced before replacing a PROM.
Service bulletins list parts that must be installed when a PROM is changed, and provide information
on trouble codes, troubleshooting and driveability problems for which the PROM was released.
To find applicable TSB's:
Complete TSB Listing
1. Hold down right mouse button and select "Vehicle" in the "Pull Right Menu". 2. Select the TSB
ICON. 3. Select "All Technical Service Bulletins by Number, Date, and Title". 4. Select "Sort by
Number", "Sort by Date", or "Sort by Title". 5. Scroll up or down to find the desired TSB.
PROM TSB Listing Only
1. Hold down right mouse button and select "Technical Service Bulletins" in the "Pull Right Menu".
2. Select "All Technical Service Bulletins for PROM - Programmable Read Only Memory". 3. Select
"Sort by Number", "Sort by Date", or "Sort by Title". 4. Scroll up or down to find the desired TSB.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6039
PROM - Programmable Read Only Memory: Application and ID Expanded Footnotes
Footnotes 1 Thru 50
[1] Also needs EGR P/N 1706739.
[2] Also requires EGR P/N 17111295.
[3] Requires Throttle Body service P/N 17067142, EGR valve service P/N 17067111, Injector
service kit P/N 17067976.
[4] Requires Throttle Body service P/N 17067142, EGR valve service P/N 17067107, Injector
service kit P/N 17067976.
[5] Requires Throttle Body service P/N 17067144, EGR valve service P/N 17067110, Injector
service kit P/N 17067976.
[6] PROM I.D. 7080 KJ is also acceptable for PROM I.D. 5853 KJ only. Requires Throttle Body
service P/N 17067144, EGR valve service P/N 17067108 (FED), 17067144 (CAL), Injector service
kit P/N 17067976.
[7] Required Throttle Body service P/N 17067142, EGR valve service P/N 17067107 (FED),
17068210 (CAL), Injector service kit P/N 17067976.
[8] Requires Throttle Body service P/N 17068019, EGR valve service P/N 17067109, Injector
service kit P/N 17067976.
[9] For Federal - Use 01226047 (PROM CODE 7654 BKW). For California - Use 01226049 (PROM
CODE 7665 BKY).
[10] For Federal - Use 01226054. For California - Use 01226056
[11] For Federal - Use 01226055. For California - Use 01226057.
[12] For Federal - Use 01226046 (PROM CODE 7648 BKU). For California - Use 01226049
(PROM CODE 7665 BKY).
[13] For federal - Use 01226046 (PROM CODE 7648 BKU). For California - Use 01226048 (PROM
CODE 7659 BKX).
[14] ECM may have been replaced by service ECM P/N 16019710 (1225500).
[15] ECM may also be 16018161. ECM may also have been replaced by service ECM P/N
16018000 (1225330).
[16] ECM may also be 16018201. ECM may also have been replaced by service ECM P/N
16018000 (1225330).
[17] ECM may also be 16018211. ECM may have been replaced by service ECM P/N 16018000
(1225330).
[18] ECM may also be 16023761. ECM may have been replaced by service ECM P/N 16018000
(1225330).
[19] ECM may also be 16018101. ECM may have been replaced by service ECM P/N 16018000
(1225330).
[20] For 2-board ECM only.
[21] May need EGR valve P/N 17079563. Original equipment P/N 16029014.
[22] Original equipment PROM P/N 16017094, now 16025254
[23] Original equipment PROM P/N 16017224, now 16025264.
[24] Also needs EGR valve P/N 17079013. Original equipment PROM P/N 16030034 (PROM ID:
BOH).
[25] Requires kit P/N 25522748 containing: Wiring harness jumper P/N 12043500, Relay P/N
25522747, Foam P/N 25522723, EGR P/N 17079799.
[26] Needs EGR valve P/N 17079818.
[27] For (MY7) - Use 01226473 (SCAN I.D. = 3941). For (M19) - Use 01226474 (SCAN I.D. =
3951).
[28] For (MY7) or (M19, C60) - Use 01226473 (SCAN I.D. = 3941). For (M19) - Use 01226474
(SCAN I.D. = 3951).
[29] ECM may also be 16023561(M5), or 16033061(M4 with A/C).
[30] For F62 axle - Use 01226441 (SCAN I.D. = 3622). For F17 axle - Use 01226439 (SCAN I.D. =
3332).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6040
[31] For one_board ECM only.
[32] Requires Thermac Sensor P/N 8997916.
[33] For Federal - Use 01227729 (SCAN I.D. = 7729). For California - Use 01227728 (SCAN I.D. =
7728).
[34] Use 01227629 (SCAN I.D. = 7629) only to resolve surge or chuggle.
[35] Use 01227381 (SCAN I.D. = 7381) only to resolve chuggle.
[36] Use 01227386 (SCAN I.D. = 7386) only to resolve chuggle.
[37] Retrofit PROM - Does not supersede the regular replacement service PROM. To be used only
as required to resolve cases of chuggle.
[38] Retrofit PROM - Supersedes all previous service PROM part numbers. To be used as both the
regular service replacement (PROM-damaged or
defective), and to resolve cases of chuggle.
[39] Retrofit PROM - Supersedes all previous service PROM part numbers. To be used as both the
regular service replacement (PROM-damaged or
defective), and to resolve cases of chuggle, detonation, or flatness.
[40] Retrofit PROM - Does not supersede the regular replacement service PROMS. To be used
only as required to resolve cases of chuggle, detonation,
or flatness.
[41] Need EGR valve P/N 17111577 (Federal only).
[42] For use with P215/65 tires - use 01228290 (SCAN I.D. = 8290). For use with P235/60,
P245/50 tires - use 01228291 (SCAN I.D. = 8291).
[43] For use with P215/65 tires - use 01228292 (SCAN I.D. - 8292). For use with P235/60, P245/50
tires - use 01228293 (SCAN I.D. = 8293).
[44] Use 16143570 (SCAN I.D. = 3531) for hot hard restart (Requires Fuel Pump P/N 25115764,
Fuel Sender P/N 25093526). Use 16143459 (SCAN
I.D. = 3571) for Code 42, Spark Knock, High Idle.
[45] Use 16143455 (SCAN I.D. = 3511) for hot hard restart (Requires Fuel Pump P/N 25115764,
Fuel Sender P/N 25093526). Use 16143453 (SCAN
I.D. = 3501) for Code 42, Spark Knock, High Idle.
[46] Use 16143575 (SCAN I.D. = 3541) for hot hard restart (Requires Fuel Pump P/N 25115764).
Use 16143460 (SCAN I.D. = 3581) for Code 42,
Spark Knock, High Idle.
[47] Use 16143580 (SCAN I.D. = 3551) for hot hard restart (Requires Fuel Pump P/N 25115764).
Use 16143462 (SCAN I.D. = 3591) for Code 42,
Spark Knock, High Idle.
[48] Use 16143457 (SCAN I.D. = 3521) for hot hard restart (Requires Fuel Pump P/N 25115925,
Fuel Sender P/N 25092778). Use 16143466 (SCAN
I.D. = 3481) for Code 42, Spark Knock, High Idle.
[49] Use 16143452 (SCAN I.D. = 3491) for hot hard restart (Requires Fuel Pump P/N 25115925,
Fuel Sender P/N 25092778). Use 16143463 (SCAN
I.D. = 3451) for Code 42, Spark Knock, High Idle.
[50] Needs air injection service kit (P/N 10115773) and new vehicle emission control label.
Footnotes 51 Thru 100
[51] Must be ordered with service kit P/N 10115773.
[52] With this PROM installed, use 1987-88 2.8L speed density engine driveability and emissions
manual.
[53] PROM update eliminates MAF sensor, replacing it with a speed density system. With a 1990
or earlier primary cartridge, I.D. vehicle on scanner
as a 1989 model (VIN = K-1-W).
[54] For 2WD use 16120099 (SCAN I.D. = 9941). For 4WD use 16120109 (SCAN I.D. = 9901).
[55] For 2.73 (GU2) Axle use 16120077 (SCAN I.D. = 9891). For 3.08 (GU4) Axle use 16120082
(SCAN I.D. = 9901). For 3.42 (GU6) and 3.73
(GT4) Axles use 16120086 (SCAN I.D. = 9911).
[56] For 2WD use 16120042 (SCAN I.D. = 9991). For 4WD use 16120129 (SCAN I.D. = 0011).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6041
[57] Needs accelerator pump check ball spring P/N 17069583.
[58] For false Code 44 on long coast down, use retrofit service PROM 01228486 AAND 1050. For
regular service replacement, use PROM 16062797
AAND 2798.
[59] For false Code 44 on long coast down, use retrofit service PROM 01228487 AANF 1052. For
regular service replacement, use PROM 16062801
AANF 2802.
[60] USE 16143545 (SCAN I.D. = 3461) For hot hard restart (Requires Fuel Pump P/N 25115764,
Fuel Sender P/N 25093744). Use 16143465 (SCAN
I.D. = 3471) for Code 42, Spark Knock, High Idle.
[61] With this PROM installed, use 1987-88 2.8L speed density engine driveability and emissions
manual.
[62] For use with model C1 Trucks - Use 16121162 (SCAN I.D. = 3511). For use with model C2, K,
K2, AND K1000 Trucks - use 16121166 (SCAN
I.D. = 3521).
[63] Also requires installation of new EGR valve package P/N 17112238 (Contains EGR valve P/N
17090078 and a gasket).
[64] Use 16181863 (SCAN I.D. = 0844) for cold start stall. Use 16181859 (SCAN I.D. = 0834) only
if required to solve both cold start stall and
chuggle.
[65] Use 16181871 (SCAN I.D. = 0864) for cold start stall. Use 16181867 (SCAN I.D. = 0854) only
if required to solve both cold start stall and
chuggle.
[66] Use 16165848 (SCAN I.D. = 5614) for cold start stall. Use 16165843 (SCAN I.D. = 5624) only
if required to solve both cold start stall and
chuggle.
[67] Do not rely on the scanner ID to determine which PROM is in a vehicle. Look at the BCC on
the PROM to be sure. Do not confuse with some
1991 models with a 2.84 axle ratio and a Federal emissions pkg which used scanner ID 5644 but
had a BCC of AWJD.
[68] This PROM may have a negative impact on fuel economy.
[69] Cannot be used on vehicles that do not have digital EGR valves.
[70] Use 16165839 (SCAN I.D. = 5634) for cold start stall. Use 16165829 (SCAN I.D. = 5644) only
if required to solve both cold start stall and
chuggle.
[71] Use 16181883 (SCAN I.D. = 0894) for cold start stall. Use 16181875 (SCAN I.D. = 0874) only
if required to solve both cold start stall and
chuggle.
[72] Use 16181887 (SCAN I.D. = 0904) for cold start stall. Use 16181879 (SCAN I.D. = 0884) only
if required to solve both cold start stall and
chuggle.
[73] This PROM may have a negative impact on fuel economy.
[74] PROM can only be used with ECM P/N 16144288.
[75] Make certain the vehicle has been updated with previously attempted service fixes as follows:
EGR valve P/N 17090156 (stamped on valve)
17112373 (GMSPO kit), PCV valve P/N 25098542, ESC module P/N 16175099 (BCC=BARC).
[76] For vehicles with sleeve bearing engines.
[77] Combination detonation and neutral gear rattle PROM available.
[78] Needs ESC P/N 16175099.
[79] Model 2DDM Transmissions - Check dealer records to see if the torque converter has already
been replaced with P/N 8650935 (Tagged BCC:
DGAF). Trans. with torque converters with P/N 8656959 (Tagged BCC: DG5F) need to replace it
with P/N 8650935.
[80] For dedicated natural gas vehicles. Order with kit P/N 12545589 unless the only problem is
idle fluctuation.
[81] For chuggle at 40-45 condition, use PROM only. For tip-in hesitation only, use EGR valve only
- P/N 17078431. For cold driveability hesitation,
use both PROM and EGR.
[82] Requires supplementary tune-up label, spark bypass relay kit P/N 14086983, spark plugs P/N
5614009, sun visor starting label P/N 14085150.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6042
Also, remove and discard fuse labeled "crank" from fuse BLK #2 position (3 Amp. Fuse).
[83] Manual transmission cars should also be updated with the clutch anticipate switch per dealer
service bulletin number. 91-472-7C.
[84] Cold driveability, use with PROM 0051 AAF (G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067111, INJECTOR SERVICE KIT P/N 17067976.
[85] Cold driveability, use with PROM 0050 AAF (G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067111, INJECTOR SERVICE KIT P/N 17067976.
[86] Exhaust noise (requires catalytic converter), cold driveability, use with PROM 5884 BH (G057).
REQUIRES THROTTLE BODY SERVICE
P/N 17068019, EGR VALVE SERVICE P/N 17067109, INJECTOR SERVICE KIT P/N 17067976.
[87] Exhaust noise (requires catalytic converter), cold driveability, use with PROM 5869 BH (G057).
REQUIRES THROTTLE BODY SERVICE
P/N 17068019, EGR VALVE SERVICE P/N 17067109, INJECTOR SERVICE KIT P/N 17067976.
[88] Exhaust noise (requires catalytic converter), cold driveability, use with PROM 5779 KB (G057).
REQUIRES THROTTLE BODY SERVICE
P/N 17067144, EGR VALVE SERVICE P/N 17067110, INJECTOR SERVICE KIT P/N 17067976.
[89] Exhaust noise (requires catalytic converter), cold driveability, use with PROM 5778 KB (G057).
REQUIRES THROTTLE BODY SERVICE
P/N 17067144, EGR VALVE SERVICE P/N 17067110, INJECTOR SERVICE KIT P/N 17067976.
[90] Cold driveability, use with PROM 5854 KJ (G057). PROM I.D. 7080 KJ IS ALSO
ACCEPTABLE FOR PROM I.D. 5853 KJ ONLY.
REQUIRES THROTTLE BODY SERVICE P/N 17067144, EGR VALVE SERVICE P/N 17067108
(FED), 17067144 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[91] Cold driveability, use with PROM 5853 KJ (G057). PROM I.D. 7080 KJ IS ALSO
ACCEPTABLE FOR PROM I.D. 5853 KJ ONLY.
REQUIRES THROTTLE BODY SERVICE P/N 17067144, EGR VALVE SERVICE P/N 17067108
(FED), 17067144 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[92] Cold driveability, use with PROM 5861 KK (G057). REQUIRED THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067107 (FED), 17068210 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[93] Cold driveability, use with PROM 5860 KK (G057). REQUIRED THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067107 (FED), 17068210 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[94] Exhaust noise (requires catalytic converter), cold driveability, use with PROM 5786 LW
(G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N 17067107, INJECTOR SERVICE KIT P/N 17067976.
[95] Exhaust noise (requires catalytic converter), cold driveability, use with PROM 5785 LW
(G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N 17067107, INJECTOR SERVICE KIT P/N 17067976.
[96] Cold driveability, use with PROM 7088 LY (G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067111, INJECTOR SERVICE KIT P/N 17067976.
[97] Cold driveability, use with PROM 7087 LY (G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067111, INJECTOR SERVICE KIT P/N 17067976.
[98] Chuggle at 40-45 mph, cold driveability hesitation. FOR CHUGGLE AT 40-45 CONDITION,
USE PROM ONLY. FOR TIP-IN HESITATION
ONLY, USE EGR VALVE ONLY - P/N 17078431. FOR COLD DRIVEABILITY HESITATION, USE
BOTH PROM AND EGR.
[99] Driveability correction for heavy chuggle. REQUIRES KIT P/N 25522748 CONTAINING:
WIRING HARNESS JUMPER P/N 12043500,
RELAY P/N 25522747, FOAM P/N 25522723, EGR P/N 17079799.
[100] Cold startability adjustment. REQUIRES SUPPLEMENTARY TUNE-UP LABEL, SPARK
BYPASS RELAY KIT P/N 14086983, SPARK
PLUGS P/N 5614009, SUN VISOR STARTING LABEL P/N 14085150. ALSO, REMOVE AND
DISCARD FUSE LABELED "CRANK" FROM FUSE BLK #2 POSITION (3 AMP. FUSE).
Footnotes 101 Thru 150
[101] Driveability correction for heavy chuggle. REQUIRES KIT P/N 25522748 CONTAINING:
WIRING HARNESS JUMPER P/N 12043500,
RELAY P/N 25522747, FOAM P/N 25522723, EGR P/N 17079799.
[102] Cold startability adjustment. REQUIRES SUPPLEMENTARY TUNE-UP LABEL, SPARK
BYPASS RELAY KIT P/N 14086983, SPARK
PLUGS P/N 5614009, SUN VISOR STARTING LABEL P/N 14085150. ALSO, REMOVE AND
DISCARD FUSE LABELED "CRANK" FROM FUSE BLK #2 POSITION (3 AMP. FUSE).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6043
[103] Cold startability adjustment. REQUIRES SUPPLEMENTARY TUNE-UP LABEL, SPARK
BYPASS RELAY KIT P/N 14086983, SPARK
PLUGS P/N 5614009, SUN VISOR STARTING LABEL P/N 14085150. ALSO, REMOVE AND
DISCARD FUSE LABELED "CRANK" FROM FUSE BLK #2 POSITION (3 AMP. FUSE).
[104] Cold startability adjustment. REQUIRES SUPPLEMENTARY TUNE-UP LABEL, SPARK
BYPASS RELAY KIT P/N 14086983, SPARK
PLUGS P/N 5614009, SUN VISOR STARTING LABEL P/N 14085150. ALSO, REMOVE AND
DISCARD FUSE LABELED "CRANK" FROM FUSE BLK #2 POSITION (3 AMP. FUSE).
[105] Surge. RETROFIT PROM - DOES NOT SUPERSEDE THE REGULAR REPLACEMENT
SERVICE PROM. TO BE USED ONLY AS
REQUIRED TO RESOLVE CASES OF CHUGGLE.
[106] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE.
[107] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE.
[108] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE.
[109] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE.
[110] Surge. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM PART
NUMBERS. TO BE USED AS BOTH THE
REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO RESOLVE
CASES OF CHUGGLE.
[111] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE.
[112] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE, DETONATION, OR FLATNESS.
[113] Surge and CODE 51. RETROFIT PROM - SUPERSEDES ALL PREVIOUS SERVICE PROM
PART NUMBERS. TO BE USED AS BOTH
THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR DEFECTIVE), AND TO
RESOLVE CASES OF CHUGGLE, DETONATION, OR FLATNESS.
[114] Surge, flatness or tip-in hesitation. RETROFIT PROM - DOES NOT SUPERSEDE THE
REGULAR REPLACEMENT SERVICE PROMS.
TO BE USED ONLY AS REQUIRED TO RESOLVE CASES OF CHUGGLE, DETONATION, OR
FLATNESS.
[115] FOR USE WITH P215/65 TIRES - USE 01228290 (SCAN I.D. = 8290). FOR USE WITH
P235/60, P245/50 TIRES - USE 01228291 (SCAN
I.D. = 8291).
[116] FOR USE WITH P215/65 TIRES - USE 01228290 (SCAN I.D. = 8290). FOR USE WITH
P235/60, P245/50 TIRES - USE 01228291 (SCAN
I.D. = 8291).
[117] Spark knock only. USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764, FUEL
SENDER P/N 25093526). USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK,
HIGH IDLE.
[118] Spark knock only. USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764, FUEL
SENDER P/N 25093526). USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK,
HIGH IDLE.
[119] Spark knock. USE 16143575 (SCAN I.D. = 3541) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764). USE 16143460
(SCAN I.D. = 3581) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[120] Detonation. USE 16143580 (SCAN I.D. = 3551) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764). USE 16143462
(SCAN I.D. = 3591) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[121] Stall, sags, hesitation. USE 16143575 (SCAN I.D. = 3541) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764). USE
16143460 (SCAN I.D. = 3581) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[122] USE 16143575 (SCAN I.D. = 3541) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764). USE 16143460 (SCAN I.D. =
3581) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[123] USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6044
USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[124] USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[125] USE 16143457 (SCAN I.D. = 3521) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115925, FUEL SENDER P/N 25092778).
USE 16143466 (SCAN I.D. = 3481) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[126] USE 16143452 (SCAN I.D. = 3491) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115925, FUEL SENDER P/N 25092778).
USE 16143463 (SCAN I.D. = 3451) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[127] USE 16143457 (SCAN I.D. = 3521) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115925, FUEL SENDER P/N 25092778).
USE 16143466 (SCAN I.D. = 3481) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[128] USE 16143452 (SCAN I.D. = 3491) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115925, FUEL SENDER P/N 25092778).
USE 16143463 (SCAN I.D. = 3451) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[129] Engine stall and/or hesitation after cold start. NEEDS AIR INJECTION SERVICE KIT (P/N
10115773) AND NEW VEHICLE EMISSION
CONTROL LABEL.
[130] Engine stall and/or hesitation after cold start. NEEDS AIR INJECTION SERVICE KIT (P/N
10115773) AND NEW VEHICLE EMISSION
CONTROL LABEL.
[131] Driveability conditions and/or stored engine codes. WITH THIS PROM INSTALLED, USE
1987-88 2.8L SPEED DENSITY ENGINE
DRIVEABILITY AND EMISSIONS MANUAL.
[132] Cold stall and chuggle. DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH
PROM IS IN A VEHICLE. LOOK AT THE
BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A
2.84 AXLE RATIO AND A FEDERAL EMISSIONS PKG. WITH USED SCANNER ID 5644 BUT
HAD A BCC OF AWJD.
[133] Driveability conditions and/or stored engine codes. WITH THIS PROM INSTALLED, USE
1987-88 2.8L SPEED DENSITY ENGINE
DRIVEABILITY AND EMISSIONS MANUAL.
[134] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on clutch operation, with manual transmission equipped vehicle. WITH THIS
PROM INSTALLED, USE 1987-88 2.8L SPEED DENSITY ENGINE DRIVEABILITY AND
EMISSIONS MANUAL.
[135] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on declutch operation with manual transmission equipped vehicle. WITH
THIS PROM INSTALLED, USE 1987-88 2.8L SPEED DENSITY ENGINE DRIVEABILITY AND
EMISSIONS MANUAL.
[136] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[137] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[138] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[139] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[140] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[141] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[142] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6045
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[143] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[144] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[145] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[146] PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED DENSITY
SYSTEM. WITH A 1990 OR EARLIER
PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989 MODEL (VIN = K-1-W).
[147] PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED DENSITY
SYSTEM. WITH A 1990 OR EARLIER
PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989 MODEL (VIN = K-1-W).
[148] PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED DENSITY
SYSTEM. WITH A 1990 OR EARLIER
PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989 MODEL (VIN = K-1-W).
[149] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on declutch operation with manual transmission equipped vehicle. PROM
UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED DENSITY SYSTEM.
WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989
MODEL (VIN = K-1-W).
[150] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on declutch operation with manual transmission equipped vehicle. PROM
UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED DENSITY SYSTEM.
WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989
MODEL (VIN = K-1-W).
Footnotes 151 Thru 200
[151] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[152] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[153] Driveability improvement and eliminate FALSE "Service Engine Soon" lights. FOR 2WD USE
16120099 (SCAN I.D. = 9941). FOR 4WD
USE 16120109 (SCAN I.D. = 9901).
[154] Driveability improvement and eliminate FALSE "Service Engine Soon" lights. FOR 2.73
(GU2) AXLE USE 16120077 (SCAN I.D. = 9891).
FOR 3.08 (GU4) AXLE USE 16120082 (SCAN I.D. = 9901). FOR 3.42 (GU6) AND 3.73 (GT4)
AXLES USE 16120086 (SCAN I.D. = 9911).
[155] Driveability improvement and eliminate FALSE "Service Engine Soon" lights. FOR 2WD USE
16120042 (SCAN I.D. = 9991). FOR 4WD
USE 16120129 (SCAN I.D. = 0011).
[156] Prom calibration. FOR FALSE CODE 44 ON LONG COAST DOWN, USE RETROFIT
SERVICE PROM 01228486 AAND 1050. FOR
REGULAR SERVICE REPLACEMENT, USE PROM 16062797 AAND 2798.
[157] FOR FALSE CODE 44 ON LONG COAST DOWN, USE RETROFIT SERVICE PROM
01228487 AANF 1052. FOR REGULAR SERVICE
REPLACEMENT, USE PROM 16062801 AANF 2802.
[158] Spark knock only. USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764, FUEL
SENDER P/N 25093526). USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK,
HIGH IDLE.
[159] Spark knock only. USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764, FUEL
SENDER P/N 25093526). USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK,
HIGH IDLE.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6046
[160] Detonation. USE 16143580 (SCAN I.D. = 3551) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764). USE 16143462
(SCAN I.D. = 3591) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[161] USE 16143545 (SCAN I.D. = 3461) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093744).
USE 16143465 (SCAN I.D. = 3471) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[162] USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[163] USE 16143545 (SCAN I.D. = 3461) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093744).
USE 16143465 (SCAN I.D. = 3471) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[164] USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[165] USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[166] Hard start when hot and detonation. USE 16143457 (SCAN I.D. = 3521) FOR HOT HARD
RESTART (REQUIRES FUEL PUMP P/N
25115925, FUEL SENDER P/N 25092778). USE 16143466 (SCAN I.D. = 3481) FOR CODE 42,
SPARK KNOCK, HIGH IDLE.
[167] Hard start when hot and detonation. USE 16143452 (SCAN I.D. = 3491) FOR HOT HARD
RESTART (REQUIRES FUEL PUMP P/N
25115925, FUEL SENDER P/N 25092778). USE 16143463 (SCAN I.D. = 3451) FOR CODE 42,
SPARK KNOCK, HIGH IDLE.
[168] Engine stall and/or hesitation after cold start. NEEDS AIR INJECTION SERVICE KIT (P/N
10115773) AND NEW VEHICLE EMISSION
CONTROL LABEL.
[169] Cold stall and chuggle. DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH
PROM IS IN A VEHICLE. LOOK AT THE
BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A
2.84 AXLE RATIO AND A FEDERAL EMISSIONS PKG. WHICH USED SCANNER ID 5644 BUT
HAD A BCC OF AWJD.
[170] Engine stall and/or hesitation after cold start. NEEDS AIR INJECTION SERVICE KIT (P/N
10115773) AND NEW VEHICLE EMISSION
CONTROL LABEL.
[171] Engine stall and/or hesitation after cold start. MUST BE ORDERED WITH SERVICE KIT P/N
10115773.
[172] Driveability conditions and/or stored engine codes. WITH THIS PROM INSTALLED, USE
1987-88 2.8L SPEED DENSITY ENGINE
DRIVEABILITY AND EMISSIONS MANUAL.
[173] Driveability conditions and/or stored engine codes. WITH THIS PROM INSTALLED, USE
1987-88 2.8L SPEED DENSITY ENGINE
DRIVEABILITY AND EMISSIONS MANUAL.
[174] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[175] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[176] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[177] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[178] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[179] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6047
[180] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[181] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[182] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[183] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[184] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[185] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[186] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[187] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[188] Driveability conditions, and/or CODES 23,25,33,34. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[189] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[190] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[191] Information on PROM calibrations. PROM UPDATE ELIMINATES MAF SENSOR,
REPLACING IT WITH A SPEED DENSITY SYSTEM.
WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989
MODEL (VIN = K-1-W).
[192] Information on PROM calibrations. PROM UPDATE ELIMINATES MAF SENSOR,
REPLACING IT WITH A SPEED DENSITY SYSTEM.
WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989
MODEL (VIN = K-1-W).
[193] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[194] Driveability conditions and/or stored engine codes. PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[195] FOR USE WITH MODEL C1 TRUCKS - USE 16121162 (SCAN I.D. = 3511). FOR USE
WITH MODEL C2, K, K2, AND K1000 TRUCKS USE 16121166 (SCAN I.D. = 3521).
[196] Engine surge. ALSO REQUIRES INSTALLATION OF NEW EGR VALVE PACKAGE P/N
17112238 (CONTAINS EGR VALVE P/N
17090078 AND A GASKET).
[197] Engine stall and/or hesitation after cold start. NEEDS AIR INJECTION SERVICE KIT (P/N
10115773) AND NEW VEHICLE EMISSION
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6048
CONTROL LABEL.
[198] Engine stall and/or hesitation after cold start. NEEDS AIR INJECTION SERVICE KIT (P/N
10115773) AND NEW VEHICLE EMISSION
CONTROL LABEL.
[199] Cold stall and chuggle. DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH
PROM IS IN A VEHICLE. LOOK AT THE
BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A
2.84 AXLE RATIO AND A FEDERAL EMISSIONS PKG. WHICH USED SCANNER ID 5644 BUT
HAD A BCC OF AWJD.
[200] Cold stall and chuggle. DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH
PROM IS IN A VEHICLE. LOOK AT THE
BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A
2.84 AXLE RATIO AND A FEDERAL EMISSIONS PKG. WHICH USED SCANNER ID 5644 BUT
HAD A BCC OF AWJD.
Footnotes 201 Thru 250
[201] Cold engine extended crank. USE 16181863 (SCAN I.D. = 0844) FOR COLD START STALL.
USE 16181859 (SCAN I.D. = 0834) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[202] Cold engine extended crank. USE 16181863 (SCAN I.D. = 0844) FOR COLD START STALL.
USE 16181859 (SCAN I.D. = 0834) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[203] Cold engine extended crank. USE 16181863 (SCAN I.D. = 0844) FOR COLD START STALL.
USE 16181859 (SCAN I.D. = 0834) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[204] Cold engine extended crank. USE 16181871 (SCAN I.D. = 0864) FOR COLD START STALL.
USE 16181867 (SCAN I.D. = 0854) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[205] Cold engine extended crank. USE 16181871 (SCAN I.D. = 0864) FOR COLD START STALL.
USE 16181867 (SCAN I.D. = 0854) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[206] Cold stall and chuggle. DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH
PROM IS IN A VEHICLE. LOOK AT THE
BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A
2.84 AXLE RATIO AND A FEDERAL EMISSIONS PKG. WHICH USED SCANNER ID 5644 BUT
HAD A BCC OF AWJD.
[207] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[208] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[209] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[210] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[211] Engine stall, long cranks/idle/decel/surge. CANNOT BE USED ON VEHICLES THAT DO
NOT HAVE DIGITAL EGR VALVES.
[212] Cold stall and chuggle. DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH
PROM IS IN A VEHICLE. LOOK AT THE
BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A
2.84 AXLE RATIO AND A FEDERAL EMISSIONS PKG. WHICH USED SCANNER ID 5644 BUT
HAD A BCC OF AWJD.
[213] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[214] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[215] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[216] Cold start extended crank. Engine starts with ignition key cycled. USE 16181883 (SCAN I.D.
= 0894) FOR COLD START STALL. USE
16181875 (SCAN I.D. = 0874) ONLY IF REQUIRED TO SOLVE BOTH COLD START STALL AND
CHUGGLE.
[217] Cold start extended crank, engine starts with ignition key cycled. USE 16181883 (SCAN I.D.
= 0894) FOR COLD START STALL. USE
16181875 (SCAN I.D. = 0874) ONLY IF REQUIRED TO SOLVE BOTH COLD START STALL AND
CHUGGLE.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6049
[218] Cold engine extended crank. USE 16181887 (SCAN I.D. = 0904) FOR COLD START STALL.
USE 16181879 (SCAN I.D. = 0884) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[219] Cold engine extended crank. USE 16181887 (SCAN I.D. = 0904) FOR COLD START STALL.
USE 16181879 (SCAN I.D. = 0884) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[220] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[221] Surge or chuggle on decel and/or rough idle. PROM CAN ONLY BE USED WITH ECM P/N
16144288.
[222] Surge or chuggle on decel and/or rough idle. PROM CAN ONLY BE USED WITH ECM P/N
16144288.
[223] Engine stall. MANUAL TRANSMISSION CARS SHOULD ALSO BE UPDATED WITH THE
CLUTCH ANTICIPATE SWITCH PER
DEALER SERVICE BULLETIN NO. 91-472-7C.
[224] USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL. USE 16165843 (SCAN I.D.
= 5624) ONLY IF REQUIRED TO SOLVE
BOTH COLD START STALL AND CHUGGLE.
[225] USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL. USE 16165829 (SCAN I.D.
= 5644) ONLY IF REQUIRED TO SOLVE
BOTH COLD START STALL AND CHUGGLE.
[226] USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL. USE 16165829 (SCAN I.D.
= 5644) ONLY IF REQUIRED TO SOLVE
BOTH COLD START STALL AND CHUGGLE.
[227] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[228] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[229] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[230] Surge or chuggle on decel and/or rough idle. PROM CAN ONLY BE USED WITH ECM P/N
16144288.
[231] MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH PREVIOUSLY ATTEMPTED
SERVICE FIXES AS FOLLOWS: EGR
VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO KIT), PCV VALVE P/N
25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[232] Driveability improvements. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH
PREVIOUSLY ATTEMPTED SERVICE
FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO
KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[233] Driveability improvements. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH
PREVIOUSLY ATTEMPTED SERVICE
FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO
KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[234] Driveablity improvements. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH
PREVIOUSLY ATTEMPTED SERVICE
FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO
KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[235] Driveability improvements. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH
PREVIOUSLY ATTEMPTED SERVICE
FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO
KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[236] Center Port Fuel Injection noise. FOR VEHICLES WITH SLEEVE BEARING ENGINES.
[237] Neutral gear rattle only. COMBINATION DETONATION AND NEUTRAL GEAR RATTLE
PROM AVAILABLE.
[238] Driveability improvements. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH
PREVIOUSLY ATTEMPTED SERVICE
FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO
KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[239] TCC chuggle. MODEL 2DDM TRANSMISSIONS - CHECK DEALER RECORDS TO SEE IF
THE TORQUE CONVERTER HAS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6050
ALREADY BEEN REPLACED WITH P/N 8650935 (TAGGED BCC: DGAF). TRANS. WITH
TORQUE CONVERTERS WITH P/N 8656959 (TAGGED BCC: DG5F) NEED TO REPLACE IT
WITH P/N 8650935.
[240] Unstable idle in park or neutral/poor driveability. FOR DEDICATED NATURAL GAS
VEHICLES. ORDER WITH KIT P/N 12545589
UNLESS THE ONLY PROBLEM IS IDLE FLUCTUATION.
[241] Driveability improvements. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH
PREVIOUSLY ATTEMPTED SERVICE
FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO
KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[242] Information on PROM calibrations. CANNOT BE USED ON VEHICLES THAT DO NOT
HAVE DIGITAL EGR VALVES.
[243] TCC chuggle. MODEL 2DDM TRANSMISSIONS - CHECK DEALER RECORDS TO SEE IF
THE TORQUE CONVERTER HAS
ALREADY BEEN REPLACED WITH P/N 8650935 (TAGGED BCC: DGAF). TRANS. WITH
TORQUE CONVERTERS WITH P/N 8656959 (TAGGED BCC: DG5F) NEED TO REPLACE IT
WITH P/N 8650935.
[244] TCC chuggle. MODEL 2DDM TRANSMISSIONS - CHECK DEALER RECORDS TO SEE IF
THE TORQUE CONVERTER HAS
ALREADY BEEN REPLACED WITH P/N 8650935 (TAGGED BCC: DGAF). TRANS. WITH
TORQUE CONVERTERS WITH P/N 8656959 (TAGGED BCC: DG5F) NEED TO REPLACE IT
WITH P/N 8650935.
[245] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on declutch operation with manual transmission equipped vehicle.
[246] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on declutch operation with manual transmission equipped vehicle.
[247] Check engine light comes on while idling on vehicles equipped with Computer Controlled
Emission System (C.C.E.S.), driven in altitudes above
3000 feet.
[248] Engine may stop running during parking maneuver or during coast down at low speeds during
ambient temperature above 85°F.
[249] Tip-in hesitation on acceleration; engine stall or sag on cold start; engine stall on
deceleration; check engine light with CODES 23,25,33, or 34;
or engine speed flare on declutch operation with manual transmission equipped vehicle.
[250] Surge on acceleration and/or at road load speeds, false "Service Engine Soon" light (CODE
32), poor driveability during warm up, Detonation
under load.
Footnotes 251 Thru 300
[251] Hesitation or sag during the first two minutes of cold operation while vehicle is under
moderate to heavy throttle drive away, or TCC chuggle.
[252] Cold start-stall, hesitation, or sag when the engine coolant is between 36°F to 111°F (2°C to
44°C); or Inadequate AC performance when driving
at a steady speed and throttle position, between 24 to 64 MPH, when the cruise control is not being
used.
[253] Lack of throttle response on trucks equipped with governors; or hot restart driveaway sag,
both governor and non-governor trucks.
[254] Intermittent stall after cold start; engine stalling on coast down; hesitation cold; or ECM
CODES E22,E26,E32,E55,E70, and/or E85
[255] PROM I.D. 7080 KJ is also acceptable for PROM I.D. 5853 KJ only. Requires Throttle body
service P/N 17067144, EGR valve] service P/N
17067108 (FED), 17067144 (CAL), Injector service kit P/N 17067976.
[256] Requires Throttle body service P/N 17067142, EGR valve service P/N 17067107 (FED),
17068210 (CAL), Injector service kit P/N 17067976.
[257] FOR CHUGGLE AT 40-45 CONDITION, USE PROM ONLY. FOR TIP-IN HESITATION
ONLY, USE EGR VALVE ONLY - P/N
17078431. FOR COLD DRIVEABILITY HESITATION, USE BOTH PROM AND EGR.
[258] REQUIRES SUPPLEMENTARY TUNE-UP LABEL, SPARK BYPASS RELAY KIT P/N 015
14086983, SPARK PLUGS P/N 5614009, SUN
VISOR STARTING LABEL P/N 015 14085150. ALSO, REMOVE AND DISCARD FUSE LABELED
"CRANK" FROM FUSE BLK #2 POSITION (3 AMP. FUSE).
[259] DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH PROM IS IN A VEHICLE.
LOOK AT THE BCC ON THE PROM TO
BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A 2.84 AXLE RATIO AND A
FEDERAL EMISSIONS PACKAGE WITH USED SCANNER ID 5644 BUT HAD A
[260] DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH PROM IS IN A VEHICLE.
LOOK AT THE BCC ON THE PROM TO
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6051
BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A 2.84 AXLE RATIO AND A
FEDERAL EMISSIONS PACKAGE WITH USED SCANNER ID 5644 BUT HAD A
[261] DO NOT RELY ON THE SCANNER ID TO DETERMINE WHICH PROM IS IN A VEHICLE.
LOOK AT THE BCC ON THE PROM TO
BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH A 2.84 AXLE RATIO AND A
FEDERAL EMISSIONS PACKAGE WITH USED SCANNER ID 5644 BUT HAD A
[262] MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH PREVIOUSLY AT TEMPTED
SERVICE FIXES AS FOLLOWS: EGR
VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO KIT), PCV VALVE P/N
25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[263] MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED WITH PREVIOUSLY ATTEMPTED
SERVICE FIXES AS FOLLOWS: EGR
VALVE P/N 17090156 (STAMPED ON VALVE) 17112373 (GMSPO KIT), PCV VALVE P/N
25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[264] MODEL 2DDM TRANS. CARS - CHECK DLR. RECORDS TO SEE IF THE TORQUE
CONVERTER HAS ALREADY BEEN REPLACED
WITH PN 8650935 (BCC: DGAF). TRANSMISSIONS WITH TORQUE CONVERTERS WITH PN
8656959 (BCC: DG5F) NEED TO HAVE THE TORQUE CONVERTER REPLACED W
[265] MODEL 2DDM TRANS. CARS - CHECK DLR. RECORDS TO SEE IF THE TORQUE
CONVERTER HAS ALREADY BEEN REPLACED
WITH PN 8650935 (BCC: DGAF). TRANSMISSIONS WITH TORQUE CONVERTERS WITH PN
8656959 (BCC: DG5F) NEED TO HAVE THE TORQUE CONVERTER REPLACED W
[266] Vehicles equipped with Computer Controlled Emission System (C.C.E.S) experience a Check
Engine Light coming on while idling, usually when
idling time exceeds 2 minutes with transmission in gear in altitudes above 3000 feet.
[267] Cold driveability, use with PROM 5854 KJ (G057). PROM I.D. 7080 KJ IS ALSO
ACCEPTABLE FOR PROM I.D. 5853 KJ ONLY.
REQUIRES THROTTLE BODY SERVICE P/N 17067144, EGR VALVE SERVICE P/N 17067108
(FED), 17067144 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[268] Cold driveability, use with PROM 5853 KJ (G057). PROM I.D. 7079 KJ IS ALSO
ACCEPTABLE FOR PROM I.D. 5854 KJ ONLY.
REQUIRES THROTTLE BODY SERVICE P/N 17067144, EGR VALVE SERVICE P/N 17067108
(FED), 17067144 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[269] Cold driveability, use with PROM 5861 KK (G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067107 (FED), 17068210 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[270] Cold driveability, use with PROM 5860 KK (G057). REQUIRES THROTTLE BODY SERVICE
P/N 17067142, EGR VALVE SERVICE P/N
17067107 (FED), 17068210 (CAL), INJECTOR SERVICE KIT P/N 17067976.
[271] Tip-in hesitation, lack low speed performance. Used with Manual transaxle vehicles with A/C
only. Requires EGR TVS P/N 373510, and A.I.R.
valve P/N 17082701.
[272] Weak drive-away after cold start, requires EGR TVS P/N 373510. Also, for CALIFORNIA
emissions, manual transaxle, replace A.I.R.
management valve with PN 17082701.
[273] Level road surge, tip-in hesitation, lack of low speed performance - for automatic transaxles
only. (Requires EGR valve P/N 17068212). FOR
FEDERAL - USE 01226055. FOR CALIFORNIA - USE 01226057.
[274] Stall in coast down with clutch disengaged and A/C on, weak drive away after cold start ,
requires EGR TVS P/N 373510. Also, for
CALIFORNIA emissions, manual transaxle, replace A.I.R. management valve with PN 17082701.
[275] Idle shake, detonation (G043). FOR 2.5L EFI, AUTOMATIC TRANSAXLE, AND FIRST
DESIGN (3-BOARD) ECM. THE SECOND
DESIGN (2-BOARD) ECM HAS THE SPARK REVISION ALREADY INCORPORATED IN ITS
PROM.
[276] Chuggle/surge at 40-45 MPH, tip-in hesitation/sag, spark knock, requires EGR valve (G032).
FOR CHUGGLE AT 40-45 CONDITION, USE
PROM ONLY. FOR TIP-IN HESITATION ONLY, USE EGR VALVE ONLY - P/N 17078431. FOR
COLD DRIVEABILITY HESITATION, USE BOTH PROM AND EGR.
[277] Chuggle and surge at 35-55 MPH, requires EGR kit. REQUIRES KIT P/N 25522748
CONTAINING: WIRING HARNESS JUMPER P/N
12043500, RELAY P/N 25522747, FOAM P/N 25522723, EGR P/N 17079799.
[278] CODE 42, spark knock, cold startability, plug fouling (G040). REQUIRES SUPPLEMENTARY
TUNE-UP LABEL, SPARK BYPASS RELAY
KIT P/N 14086983, SPARK PLUGS P/N 5614009, SUN VISOR STARTING LABEL P/N 14085150.
ALSO, REMOVE AND DISCARD FUSE LABELED "CRANK" FROM FUSE BLK #2 POSITION (3
AMP. FUSE).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6052
[279] Chuggle and surge at 35-55 MPH, requires EGR kit (G040). REQUIRES KIT P/N 25522748
CONTAINING: WIRING HARNESS JUMPER
P/N 12043500, RELAY P/N 25522747, FOAM P/N 25522723, EGR P/N 17079799.
[280] Cold hesitation/sag, warm surge (G082). RETROFIT PROM SUPERSEDES ALL PREVIOUS
SERVICE PROM PART NUMBERS. TO BE
USED AS BOTH THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OF
DEFECTIVE), AND TO RESOLVE CASES OF CHUGGLE, DETONATION, OR FLATNESS.
[281] TCC chuggle or surge (G043). WHEN INSTALLING PROM IN A CANADIAN 1985 NB, A
CODE 13 WILL OCCUR AS THE VEHICLE
WAS NOT EQUIPPED WITH AN O2 SENSOR. TO ELIMINATE THE CODE 13, NEED TO
INSTALL O2 SENSOR # 8990741 AND CONNECT TO THE EXISTING PURPLE WIRE AND
CONNECTOR IN THE
[282] Surge or chuggle at 52-60 MPH (G071). RETROFIT PROM - DOES NOT SUPERSEDE THE
REGULAR REPLACEMENT SERVICE
PROM. TO BE USED ONLY AS REQUIRED TO RESOLVE CASES OF CHUGGLE.
[283] Surge or chuggle at 52-60 MPH (G071). RETROFIT PROM - SUPERSEDES ALL
PREVIOUS SERVICE PROM PART NUMBERS. TO BE
USED AS BOTH THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR
DEFECTIVE), AND TO RESOLVE CASES OF CHUGGLE.
[284] Chuggle, hesitation, tip-in spark knock. RETROFIT PROM - SUPERSEDES ALL PREVIOUS
SERVICE PROM PART NUMBERS. TO BE
USED AS BOTH THE REGULAR SERVICE REPLACEMENT (PROM-DAMAGED OR
DEFECTIVE), AND TO RESOLVE CASES OF CHUGGLE, DETONATION, OR FLATNESS.
[285] Chuggle, hesitation, tip-in spark knock. RETROFIT PROM - DOES NOT SUPERSEDE THE
REGULAR REPLACEMENT SERVICE
PROMS. TO BE USED ONLY AS REQUIRED TO RESOLVE CASES OF CHUGGLE,
DETONATION, OR FLATNESS.
[286] FOR USE WITH P215/65 TIRES - USE 01228290 (SCAN I.D. = 8290). FOR USE WITH
P235/60, P245/50 TIRES - USE 01228291 (SCAN
I.D. = 8291).
[287] FOR USE WITH P215/65 TIRES - USE 01228292 (SCAN I.D. = 8292). FOR USE WITH
P235/60, P245/50 TIRES - USE 01228293 (SCAN
I.D. = 8293).
[288] FALSE CODES 33, 34, 43, rough idle, chuggle, hesitation (G006,G007). USED WITH VIN
#119016 OR LATER ALUMINUM HEAD
CORVETTES AND ALL CONVERTIBLE MODELS WITH AUTOMATIC TRANSMISSION, 2.59
(GM1) AXLE ONLY.
[289] FALSE CODES 33, 34, 43, rough idle, chuggle, hesitation (G006,G007). USED FOR VIN
#119016 OR LATER ALUMINUM HAED
CORVETTES AND ALL CONVERTIBLE MODELS WITH AUTOMATIC TRANSMISSION, 2.73
(GU2)/3.07 (G44) AXLE ONLY.
[290] Spark knock. USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764, FUEL SENDER
P/N 25093526). USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[291] Spark knock. USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764, FUEL SENDER
P/N 25093526). USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[292] Spark knock (G055). USE 16143575 (SCAN I.D. = 3541) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764). USE
16143460 (SCAN I.D. = 3581) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[293] Spark knock (G043). USE 16143580 (SCAN I.D. = 3551) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764). USE
16143462 (SCAN I.D. = 3591) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[294] Stalling, tip-in hesitation/sag, rough idle, cold driveability. USE 16143575 (SCAN I.D. = 3541)
FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764). USE 16143460 (SCAN I.D. = 3581) FOR CODE 42, SPARK
KNOCK, HIGH IDLE.
[295] Hard hot restart (requires rubber bumper pkg PN 25004553, and a pulsator package PN
25094266), or CODE 42, intermittent high idle, spark
knock (G055).
[296] USE 16143575 (SCAN I.D. = 3541) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764). USE 16143460 (SCAN I.D. =
3581) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[297] USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[298] USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[299] USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6053
USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[300] Spark knock. USE 16143457 (SCAN I.D. = 3521) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115925, FUEL SENDER
P/N 25092778). USE 16143466 (SCAN I.D. = 3481) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
Footnotes 301 Thru 350
[301] Spark knock. USE 16143452 (SCAN I.D. = 3491) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115925, FUEL SENDER
P/N 25092778). USE 16143463 (SCAN I.D. = 3451) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[302] Hard start hot (requires installation of a rubber bumper pkg PN 25004553, and a pulsator pkg
PN 25094266) or CODE 42, high idle, spark knock
(G055).
[303] USE 16143457 (SCAN I.D. = 3521) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115925, FUEL SENDER P/N 25092778).
USE 16143466 (SCAN I.D. = 3481) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[304] Hard hot restart (requires rubber bumper pkg PN 25004553, and a pulsator package PN
25094266), or CODE 42, intermittent high idle, spark
knock (G055).
[305] USE 16143452 (SCAN I.D. = 3491) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115925, FUEL SENDER P/N 25092778).
USE 16143463 (SCAN I.D. = 3451) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[306] Tip-in hesitation,stall,CODES 23,25,33,or 34, or speed flare on declutch op. w/man. trans.
(CODE 23 or 25 require MAT sensor model year
diagnostics) (G027). WITH THIS PROM INSTALLED, USE 1987-88 2.8L SPEED DENSITY
ENGINE DRIVEABILITY AND EMISSIONS MANUAL.
[307] CODES 23, 25, 33, 34, driveability and stalling (G027). PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[308] Tip-in hesitation,stall,CODES 23,25,33,or 34, or speed flare on declutch op. w/man. trans.
(CODE 23 or 25 require MAT sensor model year
diagnostics). PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[309] Code 23, 25, 33, 34, driveability and stalling. PROM UPDATE ELIMINATES MAF SENSOR,
REPLACING IT WITH A SPEED DENSITY
SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS
A 1989 MODEL (VIN = K-1-W).
[310] Tip-in hesitation,stall,CODES 23,25,33,or 34, or speed flare on declutch op. w/man. trans.
(CODE 23 or 25 require MAT sensor model year
diagnostics) (G027). PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A
SPEED DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE
ON SCANNER AS A 1989 MODEL (VIN = K-1-W).
[311] High emissions, exhaust odor, starting and driveability problems (G046). Requires Connector
Bleed Assembly P/N 10105820
[312] FALSE CODES 43, 54, unstable idle. FOR 2.73 (GU2) AXLE USE 16120077 (SCAN I.D. =
9891). FOR 3.08 (GU4) AXLE USE 16120082
(SCAN I.D. = 9901). FOR 3.42 (GU6) AND 3.73 (GT4) AXLES USE 16120086 (SCAN I.D. = 9911).
[313] Running change. FOR FALSE CODE 44 ON LONG COAST DOWN, USE RETROFIT
SERVICE PROM 01228486 SCAN I.D. 8486, AAND
1050. FOR REGULAR SERVICE REPLACEMENT, USE PROM 16062797 SCAN I.D. 2223, AAND
2798.
[314] Running change. FOR FALSE CODE 44 ON LONG COAST DOWN, USE RETROFIT
SERVICE PROM 01228487 SCAN I.D. 8487, AANF
1052. FOR REGULAR SERVICE REPLACEMENT, USE PROM 16062801 SCAN I.D. 2233, AANF
2802.
[315] Surge on acceleration and/or at road load speeds, false "Service Engine Soon" light (CODE
32), poor driveability during warm up, Detonation
under load (G052).
[316] Spark knock. USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764, FUEL SENDER
P/N 25093526). USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[317] Spark knock. USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115764, FUEL SENDER
P/N 25093526). USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[318] Spark knock (G043). USE 16143580 (SCAN I.D. = 3551) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764). USE
16143462 (SCAN I.D. = 3591) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[319] Spark knock (G055). USE 16143545 (SCAN I.D. = 3461) FOR HOT HARD RESTART
(REQUIRES FUEL PUMP P/N 25115764, FUEL
SENDER P/N 25093744). USE 16143465 (SCAN I.D. = 3471) FOR CODE 42, SPARK KNOCK,
HIGH IDLE.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6054
[320] CODE 42, spark knock, intermittent high idle. IF MAJOR CONDITION IS HARD HOT
ENGINE RESTART, PROM ALSO REQUIRES
INSTALLATION OF A RUBBER BUMPER PKG PN 25004553, AND PULSATOR PKG PN
25094266.
[321] USE 16143545 (SCAN I.D. = 3461) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093744).
USE 16143465 (SCAN I.D. = 3471) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[322] USE 16143570 (SCAN I.D. = 3531) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143459 (SCAN I.D. = 3571) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[323] USE 16143455 (SCAN I.D. = 3511) FOR HOT HARD RESTART (REQUIRES FUEL PUMP
P/N 25115764, FUEL SENDER P/N 25093526).
USE 16143453 (SCAN I.D. = 3501) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[324] Spark knock. USE 16143457 (SCAN I.D. = 3521) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115925, FUEL SENDER
P/N 25092778). USE 16143466 (SCAN I.D. = 3481) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[325] Spark knock. USE 16143452 (SCAN I.D. = 3491) FOR HOT HARD RESTART (REQUIRES
FUEL PUMP P/N 25115925, FUEL SENDER
P/N 25092778). USE 16143463 (SCAN I.D. = 3451) FOR CODE 42, SPARK KNOCK, HIGH IDLE.
[326] Tip-in hesitation, stall, CODES 23, 25, 33, or 34, or speed flare on declutch op. w/man. trans.
(CODE 23 or 25 require MAT sensor model year
diagnostics) (G027). WITH THIS PROM INSTALLED, USE 1987-88 2.8L SPEED DENSITY
ENGINE DRIVEABILITY AND EMISSIONS MANUAL.
[327] CODES 23, 25, 33, 34. PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH
A SPEED DENSITY SYSTEM. WITH A
1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS A 1989 MODEL
(VIN = K-1-W).
[328] Tip-in hesitation,stall,CODES 23,25,33,or 34, or speed flare on declutch op. w/ man. trans.
(CODE 23 or 25 require MAT sensor model year
diagnostics). PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[329] Tip-in hesitation,stall,CODES 23,25,33,or 34, or speed flare on declutch op. w/ man. trans.
(CODE 23 or 25 require MAT sensor model year
diagnostics) (G027). PROM UPDATE ELIMINATES MAF SENSOR, REPLACING IT WITH A
SPEED DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE
ON SCANNER AS A 1989 MODEL (VIN = K-1-W).
[330] CODES 23, 25, 33, 34, driveability and stalling (G027). PROM UPDATE ELIMINATES MAF
SENSOR, REPLACING IT WITH A SPEED
DENSITY SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON
SCANNER AS A 1989 MODEL (VIN = K-1-W).
[331] Code 23, 25, 33, 34, driveability and stalling. PROM UPDATE ELIMINATES MAF SENSOR,
REPLACING IT WITH A SPEED DENSITY
SYSTEM. WITH A 1990 OR EARLIER PRIMARY CARTRIDGE, I.D. VEHICLE ON SCANNER AS
A 1989 MODEL (VIN = K-1-W).
[332] FOR USE WITH MODEL C1 TRUCKS - USE 16121162 (SCAN I.D. = 3511). FOR USE
WITH MODEL C2, K, K2, AND K1000 TRUCKS USE 16121166 (SCAN I.D. = 3521).
[333] Surge on acceleration and/or at road load speeds, false "Service Engine Soon" light (CODE
32), poor driveability during warm up, Detonation
under load (G052).
[334] Cold engine extended crank. USE 16181863 (SCAN I.D. = 0844) FOR COLD START STALL.
USE 16181859 (SCAN I.D. = 0834) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[335] [Cold engine extended crank. USE 16181871 (SCAN I.D. = 0864) FOR COLD START
STALL. USE 16181867 (SCAN I.D. = 0854) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[336] Engine does not stay running on initial cold start and chuggle at 35-45 MPH with TCC
engaged. New MEM-CAL may affect fuel economy. DO
NOT RELY ON THE SCANNER ID TO DETERMINE WHICH PROM IS IN A VEHICLE. LOOK AT
THE BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH
A 2.84 AXLE RATIO AND A FEDERAL EMISSIONS PACKAGE WITH SCANNER ID 5644 BUT A
BCC OF A]
[337] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[338] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[339] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6055
[340] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[341] Hesitation or sag during the first two minutes of cold operation while vehicle is under
moderate to heavy throttle driveaway, or TCC chuggle.
[342] Cold start-stall, hesitation, or sag when the engine coolant is between 36°F - 111°F (2°C 44°C); or Inadequate A/C performance when driving at
steady speed and throttle position, between 24 - 64 MPH, when the cruise control is not being
used.
[343] Engine does not stay running on initial cold start and chuggle at 35-45 MPH with TCC
engaged. New MEM-CAL may affect fuel economy. DO
NOT RELY ON THE SCANNER ID TO DETERMINE WHICH PROM IS IN A VEHICLE. LOOK AT
THE BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH
A 2.84 AXLE RATIO AND A FEDERAL EMISSIONS PACKAGE WITH SCANNER ID 5644 BUT A
BCC OF A
[344] Cold engine extended crank. USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL.
USE 16165843 (SCAN I.D. = 5624) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[345] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[346] Cold engine extended crank. USE 16181883 (SCAN I.D. = 0894) FOR COLD START STALL.
USE 16181875 (SCAN I.D. = 0874) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[347] Cold engine extended crank. USE 16181887 (SCAN I.D. = 0904) FOR COLD START STALL.
USE 16181879 (SCAN I.D. = 0884) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[348] Service Engine Soon light (SES) with a code 43 or tip-in sag, tip-in hesitation, surge at WOT,
or spark detonation when cold.
[349] Engine stall. MANUAL TRANSMISSION CARS SHOULD ALSO BE UPDATED WITH THE
CLUTCH ANTICIPATE SWITCH PER
DEALER SERVICE BULLETIN NO. 91-472-7C.
[350] Engine does not stay running on initial cold start and chuggle at 35-45 MPH with TCC
engaged. New MEM-CAL may affect fuel economy. DO
NOT RELY ON THE SCANNER ID TO DETERMINE WHICH PROM IS IN A VEHICLE. LOOK AT
THE BCC ON THE PROM TO BE SURE. DO NOT CONFUSE WITH SOME 1991 MODELS WITH
A 2.84 AXLE RATIO AND A FEDERAL EMISSIONS PACKAGE WITH SCANNER ID 5644 BUT A
BCC OF A.
Footnotes 351 Thru 400
[351] USE 16165848 (SCAN I.D. = 5614) FOR COLD START STALL. USE 16165843 (SCAN I.D.
= 5624) ONLY IF REQUIRED TO SOLVE
BOTH COLD START STALL AND CHUGGLE.
[352] USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL. USE 16165829 (SCAN I.D.
= 5644) ONLY IF REQUIRED TO SOLVE
BOTH COLD START STALL AND CHUGGLE.
[353] Cold engine extended crank. USE 16165839 (SCAN I.D. = 5634) FOR COLD START STALL.
USE 16165829 (SCAN I.D. = 5644) ONLY IF
REQUIRED TO SOLVE BOTH COLD START STALL AND CHUGGLE.
[354] Lack of throttle response on trucks equipped with governors; or hot restart driveaway sag,
both governor and non-governor trucks.
[355] Low speed driveability or detonation. MAKE CERTAIN THE VEHICLE HAS BEEN UPDATED
WITH PREVIOUSLY ATTEMPTED
SERVICE FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373
(GMSPO KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[356] Tip-in hesitation, sag, backfire, spark knock. MAKE CERTAIN THE VEHICLE HAS BEEN
UPDATED WITH PREVIOUSLY ATTEMPTED
SERVICE FIXES AS FOLLOWS: EGR VALVE P/N 17090156 (STAMPED ON VALVE) 17112373
(GMSPO KIT), PCV VALVE P/N 25098542, ESC MODULE P/N 16175099 (BCC=BARC).
[357] Hesitation or sag during the first two minutes of cold operation while vehicle is under
moderate to heavy throttle driveaway, or TCC chuggle.
[358] Sustained detonation/knock. AUTOMATIC TRANSMISSIONS REQUIRE TORQUE
CONVERTER CLUTCH (TCC) CALIBRATION. USE
OF THIS PROM IN A NON-DETONATING ENGINE MAY RESULT IN DEGRADED
DRIVEABILITY.
[359] High emissions, exhaust odor, starting and driveability problems (G046). Requires Connector
Bleed Assembly P/N 10105820
[360] Neutral gear rattle. MAY ALSO REQUIRE CLUTCH DRIVEN PLATE P/N 15961141, AND
CLUTCH PILOT BEARING P/N 14061685.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Application and ID > Introducing the GM PROM Cross Reference Index > Page 6056
COMBINATION DETONATION AND NEUTRAL GEAR RATTLE PROM AVAILABLE.
[361] Malfunction Indicator Lamp (check engine light) illuminates and may set a DTC 24 (VSS
Circuit Fault) during a California State Emissions Test.
[362] Higher than normal hydrocarbon emissions during the idle portion of the inspection and
maintenance test. Also, may exhibit a slight detonation
during a light throttle acceleration
[363] TCC chuggle. MODEL 2DDM TRANS. - CHECK DEALER RECORDS TO SEE IF THE
TORQUE CONVERTER HAS BEEN REPLACED
WITH P/N 8650935 (BCC: DGAF). TRANS. WITH TORQUE CONVERTERS WITH P/N 8656959
(BCC: DG5F) NEED TO HAVE THE TORQUE CONVERTER REPLACED WITH P/N 8650935.
[364] Cold start stall, cold tip in hesitation and/or a cold rough idle after extended idling.
Additionally, in 40-50°F ambient temp., fogging on the
inside of the front windshield which does not clear with the defroster on occurs.
[365] Poor throttle response, stall, misfire, poor cold or hot start, extended crank of the starter with
a hot engine, and/or vehicle will start and then stall
when the engine is hot. MT vehicles may also experience decel. stall and poor accel. performance.
[366] Poor throttle response, stalling, misfire, poor cold or hot starting, extended cranking of the
starter with a hot engine, and/or vehicle will start and
then stall when the engine is hot. USED WITH MANUAL TRANSMISSION ONLY.
[367] MIL illuminates and/or store a DTC 32 (EGR error) with no noticeable driveability concern,
usually occurring while climbing a grade.
[368] MIL illuminates and/or store a DTC 32 (EGR error) with no noticeable driveability concern,
usually occurring while climbing a grade, towing a
trailer or driving into a strong head wind.
[369] High emissions, exhaust odor, starting and driveability problems (G046). Requires Connector
Bleed Assembly P/N 10105820
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Description and Operation > CALPAK
PROM - Programmable Read Only Memory: Description and Operation CALPAK
CAUTION:
If the computer is found to be defective and needs replacement, remove the old CALPAK and
PROM, then place both into the replacement computer. When replacing the COMPUTER always
transfer the BROADCAST CODE and PRODUCTION ECM/PCM NUMBER to the service label on
the replacement computer.
DESCRIPTION:
The resistor network calibration called a CALPAK is located inside the computer. Its appearance
and service is similar to the PROM. The CALPAK allows fuel to be delivered if other parts of the
computer fail. The CALPAK provides the computer with calibrations for:
^ Cold Start Cranking.
^ Limp home fuel (fuel backup mode).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Description and Operation > CALPAK > Page 6059
PROM - Programmable Read Only Memory: Description and Operation EEPROM
CAUTION:
The EEPROM is soldered to the COMPUTER and cannot be serviced separately. Reprogramming
of EEPROM information is necessary when replacing a COMPUTER, or when changing the engine
and/or transaxle calibrations. Failure to do this will cause the vehicle to have a no start or poor
running condition.
It is essential that a replacement COMPUTER be reprogrammed with the correct VIN, option
content, tire size, and calibration information. Reprogramming of the EEPROM is only possible with
the Service Stall System (SSS) hardware available at authorized dealer locations. Check with a
dealer before performing COMPUTER replacement or EEPROM reprogramming.
DESCRIPTION:
The term EEPROM is defined as Electronically Erasable Programmable Read Only Memory
(EEPROM) in the COMPUTER. The EEPROM stores vehicle information such as engine and
transaxle calibrations, vehicle identification number, programmable vehicle option content and
MALF history. Vehicle information stored on the EEPROM has a major effect on how the vehicle
will operate.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Description and Operation > CALPAK > Page 6060
PROM - Programmable Read Only Memory: Description and Operation EPROM
CAUTION:
The EPROM is serviceable in some applications and can be removed for replacement. If the
COMPUTER is found to be defective and needs replacement, remove the old EPROM if applicable
and place into the new computer. When replacing the COMPUTER always transfer the
BROADCAST CODE and PRODUCTION ECM/PCM NUMBER to the service label on the
replacement computer.
DESCRIPTION:
The term EPROM means Erasable Programmable Read Only Memory (EPROM). The EPROM
functions in the same manner as a regular PROM and is programmed with data pertaining to the
vehicles weight, engine, transmission, axle ratio etc. Automotive technicians do not ERASE or
PROGRAM the EPROM in the field. Instead, the EPROM is serviced in one of two manners. Some
applications are soldered to the circuit board and require both the computer and EPROM to be
replaced as a complete unit. Other applications allow for the EPROM only to replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Description and Operation > CALPAK > Page 6061
PROM - Programmable Read Only Memory: Description and Operation MEMCAL
CAUTION:
If the COMPUTER is found to be defective and needs replacement, remove the old MEMCAL and
place it into the replacement computer. When replacing the COMPUTER always transfer the
BROADCAST CODE and PRODUCTION ECM/PCM NUMBER to the service label on the
replacement computer.
DESCRIPTION:
The MEMCAL assembly contains both the functions of the PROM and the CALPAK. Like the
PROM, it contains the calibrations needed for a specific vehicle. It also is the fuel back up control
for the computer should it become damaged or faulty.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Description and Operation > CALPAK > Page 6062
PROM - Programmable Read Only Memory: Description and Operation PROM
CAUTION:
If the computer is found to be defective and needs replacement, remove the old PROM and place it
into the replacement computer. Some ECM's are equipped with another chip called a CALPAK. If
the computer is equipped with a CALPAK chip, it will be located next to the PROM and must be
transferred along with the PROM. When replacing the computer always transfer the BROADCAST
CODE and PRODUCTION ECM/PCM NUMBER to the service label on the replacement computer.
DESCRIPTION:
To allow one type of computer to be used for many different vehicles, a device called a
Programable Read Only Memory (PROM) unit is used. The PROM is located inside the computer
and has system calibration information based upon the vehicle's axle ratio, engine, transmission,
weight, and other specific configurations of the vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Description and Operation > Page 6063
PROM - Programmable Read Only Memory: Testing and Inspection
Some control modules may have problems due to cracked solder joints on the circuit board. These
internal control module problems can cause the following symptoms:
^ Failure to start or vehicle is stalling.
^ The "CHECK ENGINE" "SERVICE ENGINE SOON" or "MALFUNCTION INDICATOR" light will
flash or light up, but no trouble codes will be present.
^ Vehicle instrument panel displays may be inoperative.
^ The control module may or may not communicate with the scanner.
^ Other intermittent driveability problems.
Incorrect PROM or MEMCAL removal and replacement can create solder joint problems or
aggravate an existing condition. See PROM or MEMCAL INSTALLATION for proper procedures.
If a solder joint problem results in a "hard" failure, normal test procedures will usually pinpoint a
faulty control module. Many symptoms caused by poor solder joints in the control module result in
intermittent problems, but they may be hard to duplicate during troubleshooting. Control modules
with solder joint problems are sensitive to heat and vibration. You can check for these internal
control module problems in either, or both, of the following ways:
^ Remove the control module from its mounting bracket and extend it on the harness so that you
can expose it to the vehicle heater ducts. Alternatively, use the flexible duct to route air from the
heater to the control module location. Then run the engine and operate the heater at the "MAX
HEAT" position. This exposes the control module to approximately 140°F.
^ With the engine running, tap on the control module several times with your hand or finger tips to
simulate vehicle vibration.
If the engine stumbles or stalls, the "CHECK ENGINE" "SERVICE ENGINE SOON" or
"MALFUNCTION INDICATOR" light flashes, or any of the previous symptoms occur, the control
module may have bad solder joints on the circuit board.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Service and Repair > CALPAK
PROM - Programmable Read Only Memory: Service and Repair CALPAK
1. Remove ECM from vehicle.
2. Remove ECM access cover.
3. Remove Calibration Pack (CALPAK) using removal tool shown. Grasp the CALPAK carrier on
the narrow ends only. Gently rock the carrier from
end to end while applying a firm upward force.
4. Inspect the reference end of the CALPAK carrier and carefully set aside. Do not remove the
CALPAK from the carrier to confirm CALPAK
correctness. The notch in the CALPAK is referenced to the small notch in the carrier. The small
notch of the carrier must be aligned with the small notch in the socket.
CAUTION: ANY TIME THE CALPAK IS INSTALLED BACKWARDS AND THE IGNITION SWITCH
IS TURNED ON, THE CALPAK IS DESTROYED.
5. Install the CALPACK by pressing on the CALPAK carrier until it is firmly seated in the socket. Do
not press on the CALPAK, only the carrier.
6. Install ECM access cover.
7. Install ECM and perform a DIAGNOSTIC CIRCUIT CHECK to confirm proper installation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Service and Repair > CALPAK > Page 6066
PROM - Programmable Read Only Memory: Service and Repair EEPROM
CAUTION:
The Erasable Programmable Read Only Memory (EEPROM) is a permanent memory that is
physically soldered to the circuit boards within the computer. It is not serviceable and should not be
removed for replacement. If COMPUTER replacement is performed, reprogramming of the
EEPROM will be necessary. Failure to do this will cause the vehicle to have a no start or poor
running condition. Reprogramming of the EEPROM is only possible with the Service Stall System
(SSS) hardware available at authorized dealer locations. Check with a dealer before performing
COMPUTER replacement or EEPROM reprogramming.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Service and Repair > CALPAK > Page 6067
PROM - Programmable Read Only Memory: Service and Repair EPROM
REMOVAL:
^ DO NOT remove an EPROM from its packing material until you are ready to install it. DO NOT
hold an EPROM by its pins.
^ Before entering a vehicle to remove or replace an EPROM, touch an exposed metal part of the
vehicle to discharge any static charge from your body or use anti-static wrist straps. Avoid sliding
across upholstery or carpeting when removing or installing an EPROM. If this is not possible, touch
an exposed metal part of the vehicle with your free hand before removing or replacing an EPROM.
^ When available, use an antistatic grounding strap attached to your wrist and clipped to a metal
part of the vehicle body to prevent static charges from accumulating. Antistatic conductive
floormats are also available.
^ It may be desirable to remove the computer for EPROM replacement.
^ Remove computer access cover.
^ Unlock the locking levers by pressing outward toward the sides of the EPROM.
^ Remove EPROM from its socket
INSTALLATION:
EPROM/MEM-CAL Unit Installation
^ Install the replacement EPROM in the same direction.
^ VERY GENTLY PRESS down on the ends of the EPROM until the locking levers are rotated
toward the sides of the EPROM.
^ NOTE: To avoid Computer damage, do not press on the ends of the EPROM until the levers
snap into place. Do not use any vertical force beyond the minimum required to engage the EPROM
into its socket.
^ While continuing light pressure on the ends of the EPROM, use your index fingers to press the
locking levers inward until they are snapped into place. Listen for the click.
^ Install the access cover on the computer.
^ Perform FUNCTIONAL CHECK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Service and Repair > CALPAK > Page 6068
PROM - Programmable Read Only Memory: Service and Repair MEMCAL
CONDITION:
When installing a service replacement computer, the use of incorrect MEMCAL installation
procedures may cause the computer to fail before it can be installed in the vehicle. This condition
may appear as if the computer were defective when shipped to the dealership, when in fact it was
damaged while being installed. In addition this condition may also occur when installing an updated
MEMCAL into the vehicles original equipment computer.
CAUSE:
Excessive vertical force may be applied to the MEMCAL resulting in flexing of the circuit board and
damage to the connections between the circuit board and attached components. Excessive vertical
force may be generated in two ways.
^ Incorrect MEMCAL installation procedures.
^ Interference between MEMCAL and cover.
IMPORTANT CORRECTION:
This procedure supersedes any instructions regarding MEMCAL installation dated prior to
September 1990.
1. Inspect the MEMCAL to determine if a cork spacer is glued to the top side of the MEMCAL
assembly. If so, remove it prior to installation.
2. Align small notches with matching notches in Computer MEMCAL socket.
3. VERY GENTLY PRESS down on the ends of the MEMCAL until the locking levers are rotated
toward the sides of the MEMCAL.
NOTE: To avoid computer damage, do not press on the ends of the MEMCAL until the levers snap
into place. Do not use any vertical force beyond the minimum required to engage the MEMCAL into
its socket.
4. While continuing light pressure on the ends of the MEMCAL, use your index fingers to press the
locking levers inward until they are snapped into
place. Listen for the click.
5. Install MEMCAL cover and install computer cover.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Powertrain Management > PROM - Programmable Read Only Memory > Component
Information > Service and Repair > CALPAK > Page 6069
PROM - Programmable Read Only Memory: Service and Repair PROM
1. Remove ECM from vehicle.
2. Remove ECM access cover.
PROM Removal
3. Remove PROM using the rocker-type PROM removal tool shown. Engage one end of the PROM
carrier with the hook end of the tool. Press on
the vertical bar end of the tool and rock the engaged end of the PROM carrier up as far as
possible. Engage the opposite end of the PROM carrier in the same manner and rock this end up
as far as possible. Repeat this process until the PROM carrier and PROM are free of the PROM
socket. The PROM carrier with the PROM in it should lift off of the PROM socket easily.
4. Inspect the reference end of the PROM carrier and carefully set aside. Do not remove the PROM
from the carrier to confirm PROM correctness.
The notch in the PROM is referenced to the small notch in the carrier. The small notch of the
carrier must be aligned with the small notch in the socket.
CAUTION: ANY TIME THE PROM IS INSTALLED BACKWARDS AND THE IGNITION SWITCH IS
TURNED ON, THE PROM IS DESTROYED.
5. Install PROM by pressing on the PROM carrier until it is firmly seated in the socket. Do not press
on the PROM, only the carrier.
6. Install ECM access cover.
7. Install ECM and perform a DIAGNOSTIC CIRCUIT CHECK to confirm proper installation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Actuators and Solenoids - Transmission and Drivetrain >
Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service
Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Torque Converter Clutch Solenoid: Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4
Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Actuators and Solenoids - Transmission and Drivetrain >
Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service
Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6077
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Actuators and Solenoids - Transmission and Drivetrain >
Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service
Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6078
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Actuators and Solenoids - Transmission and Drivetrain >
Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service
Bulletins > Page 6079
Torque Converter Clutch Solenoid: Service and Repair
REPLACE
1. Raise and support vehicle. 2. Disconnect heated oxygen sensor. 3. Remove catalytic converter
to muffler attaching bolts and nuts. 4. Remove catalytic converter hanger to catalytic converter
bolts. 5. Remove righthand side dampener assembly. 6. Remove nuts holding exhaust pipe to
exhaust manifold. 7. Remove converter and pipe assembly from vehicle. 8. Remove oil pan and oil
filter assembly. 9. Disconnect external wiring harness from transmission pass through connector.
10. Remove accumulator cover attaching bolts. 11. Remove 1-2 accumulator cover, piston and
spring. 12. Disconnect electrical connectors. 13. Remove pressure control solenoid retainer bolt,
then the retainer and solenoid. 14. Remove TCC solenoid retaining bolts. 15. Remove
pass-through electrical connector from transmission case by positioning the small end of power
piston seal protector and diaphragm
retainer installer tool No. J-28458 or equivalent, over the top of the connector, then twist tool to
release the four tabs while at the same time pulling the harness through the case.
16. Remove TCC solenoid with wiring harness from transmission case. 17. Reverse procedure to
install, noting the following:
a. Tighten TCC solenoid retaining bolt to specification. b. Tighten pressure control solenoid
retaining bolt to specification. c. When installing 1-2 accumulator piston to accumulator cover, the
piston legs must face towards the case. d. Tighten accumulator attaching bolts to specification
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Actuators and
Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > A/T 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Torque Converter Clutch Solenoid: Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4
Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Actuators and
Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > A/T 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6086
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Actuators and
Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > A/T 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6087
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Actuators and
Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > Page
6088
Torque Converter Clutch Solenoid: Service and Repair
REPLACE
1. Raise and support vehicle. 2. Disconnect heated oxygen sensor. 3. Remove catalytic converter
to muffler attaching bolts and nuts. 4. Remove catalytic converter hanger to catalytic converter
bolts. 5. Remove righthand side dampener assembly. 6. Remove nuts holding exhaust pipe to
exhaust manifold. 7. Remove converter and pipe assembly from vehicle. 8. Remove oil pan and oil
filter assembly. 9. Disconnect external wiring harness from transmission pass through connector.
10. Remove accumulator cover attaching bolts. 11. Remove 1-2 accumulator cover, piston and
spring. 12. Disconnect electrical connectors. 13. Remove pressure control solenoid retainer bolt,
then the retainer and solenoid. 14. Remove TCC solenoid retaining bolts. 15. Remove
pass-through electrical connector from transmission case by positioning the small end of power
piston seal protector and diaphragm
retainer installer tool No. J-28458 or equivalent, over the top of the connector, then twist tool to
release the four tabs while at the same time pulling the harness through the case.
16. Remove TCC solenoid with wiring harness from transmission case. 17. Reverse procedure to
install, noting the following:
a. Tighten TCC solenoid retaining bolt to specification. b. Tighten pressure control solenoid
retaining bolt to specification. c. When installing 1-2 accumulator piston to accumulator cover, the
piston legs must face towards the case. d. Tighten accumulator attaching bolts to specification
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Band, A/T >
Component Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Band: Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Band, A/T >
Component Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page
6093
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Band, A/T >
Component Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page
6094
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Case, A/T >
Component Information > Technical Service Bulletins > A/T - Cracked Case Diagnosis
Case: Technical Service Bulletins A/T - Cracked Case Diagnosis
Bulletin No.: 02-07-30-024B
Date: August 18, 2005
INFORMATION
Subject: Diagnosis of Cracked or Broken Transmission Case
Models: 2006 and Prior Cars and Light Duty Trucks 2006 and Prior HUMMER H2 2006 HUMMER
H3 2005-2006 Saab 9-7X
with 4L60/4L60-E/4L65-E or 4L80-E/4L85-E or Allison(R) Series 1000 Automatic Transmission
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 02-07-30-024A (Section 07 - Transmission/Transaxle).
Diagnosing the cause of a cracked or broken transmission case requires additional diagnosis and
repair or a repeat failure will occur.
A cracked or broken transmission case is most often the result of abnormal external torsional
forces acting on the transmission case. If none of the conditions listed below are apparent, an
internal transmission component inspection may be required. Repairs of this type may be the result
of external damage or abuse for which General Motors is not responsible. They are not the result of
defects in materials or workmanship. If in doubt, contact your General Motors Service
Representative.
The following items should be considered:
^ It is important to inspect the vehicle for signs of an out of line condition, impact damage or foreign
material to the following components:
- The transmission
- The engine mounts
- The transmission rear mount and crossmember
- Vehicle frame damage that alters the front to rear alignment of the driveshaft
- The driveshafts (both front and rear)
- The wheels (caked with mud, concrete, etc.)
- The tires (roundness, lack of cupping, excessive balance weights)
- The transfer case (if the vehicle is 4WD)
^ A worn or damaged driveshaft U-Joint has shown to be a frequent cause of transmission case
cracking, especially on vehicles that see extended periods of highway driving. Always inspect the
U-joint condition when diagnosing this condition.
^ For driveshaft damage or imbalance, Inspect the driveshafts (both front and rear) for dents,
straightness/runout or signs of missing balance weights. Also, inspect for foreign material such as
undercoat sprayed on the driveshaft.
^ The driveshaft working angles may be excessive or non-canceling, especially if the vehicle
carrying height has been altered (lifted or lowered) or if the frame has been extended or modified.
^ Damaged or worn upper or lower rear control arms or bushings.
^ A rear axle that is not seated in the rear spring properly (leaf spring vehicles).
^ Broken rear springs and or worn leaf spring bushings.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Case, A/T >
Component Information > Technical Service Bulletins > A/T - Cracked Case Diagnosis > Page 6099
In some cases, the customer may not comment about a vibration but it is important to test drive the
vehicle while using the electronic vibration analysis tool in an attempt to locate the cause of the
torsional vibration. Refer to the Vibration Diagnosis and Correction sub-section of the appropriate
Service Manual for more details on diagnosing and correcting vibrations.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Channel Plate, A/T >
Component Information > Technical Service Bulletins > A/T Control - DTC P0756 Diagnostic Tips
Channel Plate: Technical Service Bulletins A/T Control - DTC P0756 Diagnostic Tips
INFORMATION
Bulletin No.: 01-07-30-036H
Date: January 29, 2009
Subject: Diagnostic Tips for Automatic Transmission DTC P0756, Second, Third, Fourth Gear Start
Models: 2009 and Prior GM Passenger Cars and Light Duty Trucks 2009 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
with 4L60-E, 4L65-E or 4L70E Automatic Transmission (RPOs M30, M32 or M70)
Supercede:
This bulletin is being revised to add the 2009 model year and add details regarding spacer plates.
Please discard Corporate Bulletin Number 01-07-30-036G (Section 07 - Transmission/Transaxle).
Some dealership technicians may have difficulty diagnosing DTC P0756, 2-3 Shift Valve
Performance on 4L60-E, 4L65-E or 4L70E automatic transmissions. As detailed in the Service
Manual, when the PCM detects a 4-3-3-4 shift pattern, DTC P0756 will set. Some customers may
also describe a condition of a second, third or fourth gear start that may have the same causes but
has not set this DTC yet. Below are some tips when diagnosing this DTC:
^ This is a performance code. This means that a mechanical malfunction exists.
^ This code is not set by electrical issues such as a damaged wiring harness or poor electrical
connections. Electrical problems would cause a DTC P0758, P0787 or P0788 to set.
^ The most likely cause is chips/debris plugging the filtered AFL oil at orifice # 29 on the top of the
spacer plate (48). This is a very small hole and is easily plugged by a small amount of debris. It is
important to remove the spacer plate and inspect orifice # 29 and the immediate area for the
presence of chips/debris. Also, the transmission case passage directly above this orifice and the
valve body passage directly below should be inspected and cleaned of any chips/debris. For 2003
and newer vehicles the spacer plate should be replaced. The service replacement spacer plate is a
bonded style with gaskets and solenoid filter screens bonded to the spacer plate. These screens
can help to prevent plugging of orifice # 29 caused by small debris or chips.
^ This code could be set if the 2-3 shift valve (368) were stuck or hung-up in its bore. Inspect the
2-3 shift valve (368) and the 2-3 shuttle valve (369) for free movement or damage and clean the
valves, the bore and the valve body passages.
^ This code could be set by a 2-3 shift solenoid (367b) if it were cracked, broken or leaking. Refer
to Shift Solenoid Leak Test in the appropriate Service Manual for the leak test procedure. Based on
parts return findings, a damaged or leaking shift solenoid is the least likely cause of this condition.
Simply replacing a shift solenoid will not correct this condition unless the solenoid has been found
to be cracked, broken or leaking.
It is important to also refer to the appropriate Service Manual or Service Information (SI) for further
possible causes of this condition.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > Customer Interest: > 08-07-30-027 > Jun > 08 > A/T - No Movement
in Drive or 3rd Gear
Clutch: Customer Interest A/T - No Movement in Drive or 3rd Gear
TECHNICAL
Bulletin No.: 08-07-30-027
Date: June 04, 2008
Subject: No Movement When Transmission is Shifted to Drive or Third - Normal Operation When
Shifted to Second, First or Reverse (Replace Forward Sprag Assembly)
Models: 1982 - 2005 GM Passenger Cars and Light Duty Trucks 2006 - 2007 Buick Rainier 2006
Cadillac Escalade, Escalade ESV, Escalade EXT 2006 Chevrolet SSR 2006 - 2008 Chevrolet
Avalanche, Colorado, Express, Silverado Classic, Silverado, Suburban, Tahoe, TrailBlazer 2006
GMC Yukon Denali, Yukon Denali XL 2006 - 2008 GMC Canyon, Envoy, Savana, Sierra Classic,
Sierra, Yukon, Yukon XL 2006 Pontiac GTO 2006 - 2007 HUMMER H2 2006 - 2008 HUMMER H3
2006 - 2008 Saab 9-7X
with 4L60, 4L60E, 4L65E or 4L70E Automatic Transmission (RPOs MD8, M30, M32, M33 or M70)
Condition
Some customers may comment that the vehicle has no movement when the transmission is shifted
to DRIVE or THIRD position, but there is normal operation when it is shifted to SECOND, FIRST or
REVERSE position.
Cause
This condition may be caused by a damaged forward sprag assembly (642).
Correction
When inspecting the sprag, it is important to test the sprag for proper operation by holding the outer
race (644) with one hand while rotating the input sun gear (640) with the other hand. The sun gear
should rotate only in the counterclockwise direction with the input sun gear facing upward. If the
sprag rotates in both directions or will not rotate in either direction, the sprag elements should be
inspected by removing one of the sprag assembly retaining rings (643). Refer to SI Unit Repair
section for forward clutch sprag disassembly procedures.
If the sprag is found to be damaged, make repairs to the transmission as necessary. A new forward
roller clutch sprag assembly is now available from GMSPO.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > Customer Interest: > 08-07-30-027 > Jun > 08 > A/T - No Movement
in Drive or 3rd Gear > Page 6112
If clutch debris is found, it is also very important to inspect the Pressure Control (PC) solenoid
valve (377) fluid screens. Clean or replace the PC solenoid (377) as necessary. It is also important
to flush and flow check the transmission oil cooler using J45096. Refer to SI Automatic
Transmission Oil Cooler Flushing and Flow Test for the procedure.
The notches above each sprag must point up as shown when assembled into the outer race.
Bearing Assembly, Input Sun Gear
Snap Ring, Overrun Clutch Hub Retaining
Hub, Overrun Clutch
Wear Plate, Sprag Assembly
Retainer and Race Assembly, Sprag
Forward Sprag Assembly
Retainer Rings, Sprag Assembly
Outer Race, Forward Clutch
Washer, Thrust (Input Carrier to Race)
The following information applies when this sprag is used in 1982-86 transmissions.
The new design sprag can be used on models 1982 through 1986, by replacing the entire
assembly (637 - 644). Individual components are NOT
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > Customer Interest: > 08-07-30-027 > Jun > 08 > A/T - No Movement
in Drive or 3rd Gear > Page 6113
interchangeable.
Important:
The wear plate (640) and input thrust washer (660) are not required with the new sprag. Use of the
thrust washer and wear plate with the new sprag assembly will cause a misbuild (correct end play
cannot be obtained).
Parts Information
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Clutch: > 08-07-30-027 > Jun >
08 > A/T - No Movement in Drive or 3rd Gear
Clutch: All Technical Service Bulletins A/T - No Movement in Drive or 3rd Gear
TECHNICAL
Bulletin No.: 08-07-30-027
Date: June 04, 2008
Subject: No Movement When Transmission is Shifted to Drive or Third - Normal Operation When
Shifted to Second, First or Reverse (Replace Forward Sprag Assembly)
Models: 1982 - 2005 GM Passenger Cars and Light Duty Trucks 2006 - 2007 Buick Rainier 2006
Cadillac Escalade, Escalade ESV, Escalade EXT 2006 Chevrolet SSR 2006 - 2008 Chevrolet
Avalanche, Colorado, Express, Silverado Classic, Silverado, Suburban, Tahoe, TrailBlazer 2006
GMC Yukon Denali, Yukon Denali XL 2006 - 2008 GMC Canyon, Envoy, Savana, Sierra Classic,
Sierra, Yukon, Yukon XL 2006 Pontiac GTO 2006 - 2007 HUMMER H2 2006 - 2008 HUMMER H3
2006 - 2008 Saab 9-7X
with 4L60, 4L60E, 4L65E or 4L70E Automatic Transmission (RPOs MD8, M30, M32, M33 or M70)
Condition
Some customers may comment that the vehicle has no movement when the transmission is shifted
to DRIVE or THIRD position, but there is normal operation when it is shifted to SECOND, FIRST or
REVERSE position.
Cause
This condition may be caused by a damaged forward sprag assembly (642).
Correction
When inspecting the sprag, it is important to test the sprag for proper operation by holding the outer
race (644) with one hand while rotating the input sun gear (640) with the other hand. The sun gear
should rotate only in the counterclockwise direction with the input sun gear facing upward. If the
sprag rotates in both directions or will not rotate in either direction, the sprag elements should be
inspected by removing one of the sprag assembly retaining rings (643). Refer to SI Unit Repair
section for forward clutch sprag disassembly procedures.
If the sprag is found to be damaged, make repairs to the transmission as necessary. A new forward
roller clutch sprag assembly is now available from GMSPO.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Clutch: > 08-07-30-027 > Jun >
08 > A/T - No Movement in Drive or 3rd Gear > Page 6119
If clutch debris is found, it is also very important to inspect the Pressure Control (PC) solenoid
valve (377) fluid screens. Clean or replace the PC solenoid (377) as necessary. It is also important
to flush and flow check the transmission oil cooler using J45096. Refer to SI Automatic
Transmission Oil Cooler Flushing and Flow Test for the procedure.
The notches above each sprag must point up as shown when assembled into the outer race.
Bearing Assembly, Input Sun Gear
Snap Ring, Overrun Clutch Hub Retaining
Hub, Overrun Clutch
Wear Plate, Sprag Assembly
Retainer and Race Assembly, Sprag
Forward Sprag Assembly
Retainer Rings, Sprag Assembly
Outer Race, Forward Clutch
Washer, Thrust (Input Carrier to Race)
The following information applies when this sprag is used in 1982-86 transmissions.
The new design sprag can be used on models 1982 through 1986, by replacing the entire
assembly (637 - 644). Individual components are NOT
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Clutch: > 08-07-30-027 > Jun >
08 > A/T - No Movement in Drive or 3rd Gear > Page 6120
interchangeable.
Important:
The wear plate (640) and input thrust washer (660) are not required with the new sprag. Use of the
thrust washer and wear plate with the new sprag assembly will cause a misbuild (correct end play
cannot be obtained).
Parts Information
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Clutch: > 477141 > Jan > 95 >
A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Clutch: All Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Clutch: > 477141 > Jan > 95 >
A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6125
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Clutch: > 477141 > Jan > 95 >
A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6126
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Other Service Bulletins for Clutch: > 477141 > Jan > 95 > A/T 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Clutch: All Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Other Service Bulletins for Clutch: > 477141 > Jan > 95 > A/T 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6132
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Clutch, A/T >
Component Information > Technical Service Bulletins > All Other Service Bulletins for Clutch: > 477141 > Jan > 95 > A/T 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6133
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > A/T - DEXRON(R)-VI Fluid Information
Fluid - A/T: Technical Service Bulletins A/T - DEXRON(R)-VI Fluid Information
INFORMATION
Bulletin No.: 04-07-30-037E
Date: April 07, 2011
Subject: Release of DEXRON(R)-VI Automatic Transmission Fluid (ATF)
Models:
2008 and Prior GM Passenger Cars and Light Duty Trucks 2003-2008 HUMMER H2 2006-2008
HUMMER H3 2005-2007 Saturn Relay 2005 and Prior Saturn L-Series 2005-2007 Saturn ION
2005-2008 Saturn VUE with 4T45-E 2005-2008 Saab 9-7X Except 2008 and Prior Chevrolet Aveo,
Equinox Except 2006 and Prior Chevrolet Epica Except 2007 and Prior Chevrolet Optra Except
2008 and Prior Pontiac Torrent, Vibe, Wave Except 2003-2005 Saturn ION with CVT or AF23 Only
Except 1991-2002 Saturn S-Series Except 2008 and Prior Saturn VUE with CVT, AF33 or 5AT
(MJ7/MJ8) Transmission Only Except 2008 Saturn Astra
Attention:
DEXRON(R)-VI Automatic Transmission Fluid (ATF) is the only approved fluid for warranty repairs
for General Motors transmissions/transaxles requiring DEXRON(R)-III and/or prior DEXRON(R)
transmission fluids.
Supercede: This bulletin is being revised to update information. Please discard Corporate Bulletin
Number 04-07-30-037D (Section 07 - Transmission/Transaxle).
MANUAL TRANSMISSIONS / TRANSFER CASES and POWER STEERING
The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle
that previously required DEXRON(R)-III for a manual transmission or transfer case should now use
P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Some manual
transmissions and transfer cases require a different fluid. Appropriate references should be
checked when servicing any of these components.
Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid.
Consult the Parts Catalog, Owner's Manual, or Service Information (SI) for fluid recommendations.
Some of our customers and/or General Motors dealerships/Saturn Retailers may have some
concerns with DEXRON(R)-VI and DEXRON(R)-III Automatic Transmission Fluid (ATF) and
transmission warranty claims. DEXRON(R)-VI is the only approved fluid for warranty repairs for
General Motors transmissions/transaxles requiring DEXRON(R)-III and/or prior DEXRON(R)
transmission fluids (except as noted above). Please remember that the clean oil reservoirs of the
J-45096 - Flushing and Flow Tester machine should be purged of DEXRON(R)-III and filled with
DEXRON(R)-VI for testing, flushing or filling General Motors transmissions/transaxles (except as
noted above).
DEXRON(R)-VI can be used in any proportion in past model vehicles equipped with an automatic
transmission/transaxle in place of DEXRON(R)-III (i.e. topping off the fluid in the event of a repair
or fluid change). DEXRON(R)-VI is also compatible with any former version of DEXRON(R) for use
in automatic transmissions/transaxles.
DEXRON(R)-VI ATF
General Motors Powertrain has upgraded to DEXRON(R)-VI ATF with the start of 2006 vehicle
production.
Current and prior automatic transmission models that had used DEXRON(R)-III must now only use
DEXRON(R)-VI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > A/T - DEXRON(R)-VI Fluid Information > Page 6138
All 2006 and future model transmissions that use DEXRON(R)-VI are to be serviced ONLY with
DEXRON(R)-VI fluid.
DEXRON(R)-VI is an improvement over DEXRON(R)-III in the following areas:
* These ATF change intervals remain the same as DEXRON(R)-III for the time being.
2006-2008 Transmission Fill and Cooler Flushing
Some new applications of the 6L80 six speed transmission will require the use of the J 45096 Flushing and Flow Tester to accomplish transmission fluid fill. The clean oil reservoir of the
machine should be purged of DEXRON(R)-III and filled with DEXRON(R)-VI.
Parts Information
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > A/T - DEXRON(R)-VI Fluid Information > Page 6139
Fluid - A/T: Technical Service Bulletins A/T - Water Or Coolant Contamination Information
INFORMATION
Bulletin No.: 08-07-30-035B
Date: November 01, 2010
Subject: Information on Water or Ethylene Glycol in Transmission Fluid
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks with Automatic Transmission
Supercede: This bulletin is being revised to update model years. Please discard Corporate Bulletin
Number 08-07-30-035A (Section 07 - Transmission/Transaxle).
Water or ethylene glycol in automatic transmission fluid (ATF) is harmful to internal transmission
components and will have a negative effect on reliability and durability of these parts. Water or
ethylene glycol in ATF will also change the friction of the clutches, frequently resulting in shudder
during engagement or gear changes, especially during torque converter clutch engagement.
Indications of water in the ATF may include:
- ATF blowing out of the transmission vent tube.
- ATF may appear cloudy or, in cases of extreme contamination, have the appearance of a
strawberry milkshake.
- Visible water in the oil pan.
- A milky white substance inside the pan area.
- Spacer plate gaskets that appear to be glued to the valve body face or case.
- Spacer plate gaskets that appear to be swollen or wrinkled in areas where they are not
compressed.
- Rust on internal transmission iron/steel components.
If water in the ATF has been found and the source of the water entry has not been identified, or if a
leaking in-radiator transmission oil cooler is suspected (with no evidence of cross-contamination in
the coolant recovery reservoir), a simple and quick test kit is available that detects the presence of
ethylene glycol in ATF. The "Gly-Tek" test kit, available from the Nelco Company, should be
obtained and the ATF tested to make an accurate decision on the need for radiator replacement.
This can help to prevent customer comebacks if the in-radiator transmission oil cooler is leaking
and reduce repair expenses by avoiding radiator replacement if the cooler is not leaking. These
test kits can be obtained from:
Nelco Company
Test kits can be ordered by phone or through the website listed above. Orders are shipped
standard delivery time but can be shipped on a next day delivery basis for an extra charge. One
test kit will complete 10 individual fluid sample tests. For vehicles repaired under warranty, the cost
of the complete test kit plus shipping charges should be divided by 10 and submitted on the
warranty claim as a net item.
The transmission should be repaired or replaced based on the normal cost comparison procedure.
Important If water or coolant is found in the transmission, the following components MUST be
replaced.
- Replace all of the rubber-type seals.
- Replace all of the composition-faced clutch plates and/or bands.
- Replace all of the nylon parts.
- Replace the torque converter.
- Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
Important The following steps must be completed when repairing or replacing.
Flush and flow check the transmission oil cooler using J 45096. Refer to Corporate Bulletin Number
02-07-30-052F- Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096
TransFlow.
- Thoroughly inspect the engine cooling system and hoses and clean/repair as necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > A/T - DEXRON(R)-VI Fluid Information > Page 6140
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > A/T - DEXRON(R)-VI Fluid Information > Page 6141
Fluid - A/T: Technical Service Bulletins A/T - DEXRON III Fluid Introduction
File In Section: 0 - General Information
Bulletin No.: 57-02-01
Date: March, 1995
SERVICE MANUAL UPDATE
Subject: Section 0 - General Information - DEXRON(R)-III Transmission Fluid Introduction
Models: 1995 and Prior Passenger Cars and Trucks
General Motors has phased in a new automatic transmission fluid, DEXRON(R)-III, that does not
need replacing under normal service. DEXRON(R)-III is designed to help the transmission deliver
the best possible performance under all conditions. Refer to Figure 1.
The improvements in DEXRON(R)-III include better friction stability, more high temperature
oxidation stability and better material compatibility. DEXRON(R)-III has the same low temperature
fluidity as DEXRON(R)-IIE, for better transmission performance in cold weather.
DEXRON(R)-IIE and DEXRON(R)-III are fully compatible.
DEXRON(R)-III is fully compatible with any General Motors passenger vehicle or light truck with
automatic transmission and built since 1949.
Dealers should require their supplier to include the DEXRON(R)-III license number on all automatic
transmission fluid invoices.
Starting February 1, 1994 DEXRON(R)-III was phased into all North American assembly plants.
DEXRON(R)-III fluid is available from GMSPO (see fluid numbers below):
U.S.
1 Quart 12346143
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > A/T - DEXRON(R)-VI Fluid Information > Page 6142
1 Gallon 12346144
55 Gallon 12346145
In Canada
1 Liter 10952622
4 Liter 10952623
200 Liter 10952624
The 1995 Automatic Transmission/Transaxle fluid change intervals are the following:
(1994 and prior should use the schedules as written in the Owner's Manual.)
If the vehicle is mainly driven under one or more of these conditions:
In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher.
In hilly or mountainous terrain.
When doing frequent trailer towing.
Uses such as found in taxi, police car or delivery service.
Change the fluid and filter every 50,000 miles (63,000 km).
If the vehicle is not used mainly under any of these conditions, the fluid and filter do not require
periodic changing for vehicles under 8,600 GVWR.
Vehicles over 8,600 GVWR change the fluid and filter every 50,000 miles (83,000 km) regardless
of driving conditions.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > Page 6143
Fluid - A/T: Specifications
Fluid Type
........................................................................................................................................................
DEXRON-IIE or DEXRON-III auto. trans.
Capacity
Drain & Refill ........................................................................................................................................
.............................................. 4.7 liters (10.0 pt) Overhaul ..................................................................
.......................................................................................................................... 10.6 liters (22.4 pt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Fluid - A/T >
Component Information > Technical Service Bulletins > Page 6144
Fluid - A/T: Service and Repair
NOTE: The following procedure has been modified by a technical service bulletin.
1. Raise and support vehicle. 2. Proceed as follows:
a. Loosen transmission mount to support attaching nut. b. Loosen two bolts attaching right side of
transmission support to frame rail. c. Remove two bolts attaching left side transmission support to
frame rail. d. Using suitable transmission jack, support and slightly raise transmission. e. Slide
transmission support rearward enough to access rear oil pan attaching bolts.
3. Place drain pan under transmission oil pan, loosen pan bolts on front of pan, pry carefully with
screwdriver to loosen oil pan, and allow fluid to
drain.
4. Remove remaining oil pan bolts, oil pan, and gasket. 5. Drain fluid from pan, then clean pan and
dry thoroughly with compressed air. 6. Remove oil filter to valve body bolt, then the filter and
gasket. 7. Install new filter seal into case, then new filter and attaching bolt. 8. Install new gasket on
oil pan, then install oil pan and tighten bolts to specification. 9. Lower vehicle and add five quarts of
automatic transmission fluid through filler tube.
10. With selector lever in park and parking brake applied, start engine and let idle. Do not race
engine. 11. Move selector lever through each range, return to park position, check fluid, and add
additional fluid to bring level between dimples on dipstick.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec >
95 > Recall - A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec >
95 > Recall - A/T Shift Control Linkage Adjustment > Page 6154
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec >
95 > Recall - A/T Shift Control Linkage Adjustment > Page 6155
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec >
95 > Recall - A/T Shift Control Linkage Adjustment > Page 6156
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Shift
Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Shift
Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6162
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Shift
Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6163
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Shift
Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6164
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > Page 6165
Shift Indicator: Description and Operation
DESCRIPTION
This lamp is used on most models equipped with manual transmission.
OPERATION
The Upshift lamp is illuminated to inform the driver of ideal shift points, with improved fuel economy
as the specific objective. When the light is illuminated, the transmission should be shifted to the
next highest gear, if driving conditions permit such an action.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Lamps and Indicators A/T > Shift Indicator > Component Information > Technical Service Bulletins > Page 6166
Shift Indicator: Service and Repair
If upshift indicator is not working properly, perform the following test. 1. Disconnect ECM connector
C1. 2. Place ignition switch in run. 3. Measure voltage at terminal A2 of ECM connector. 4. If
battery voltage is present, further ECM diagnosis is necessary. 5. If battery voltage is not present,
repair open circuit in brown/black wire, circuit 456.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Output Shaft, A/T >
Component Information > Technical Service Bulletins > A/T - 2-3 Upshift or 3-2 Downshift Clunk Noise
Output Shaft: Technical Service Bulletins A/T - 2-3 Upshift or 3-2 Downshift Clunk Noise
INFORMATION
Bulletin No.: 01-07-30-042F
Date: February 05, 2010
Subject: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise
Models:
2010 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3
2005-2009 Saab 9-7X with 4L60-E, 4L65-E or 4L70-E Automatic Transmission (RPOs M30, M32,
M70)
Supercede: This bulletin is being revised to add the 2010 model year and 4L70E transmission.
Please discard Corporate Bulletin Number 01-07-30-042E (Section 07 - Transmission/Transaxle).
Important For 2005 model year fullsize utilities and pickups, refer to Corporate Bulletin
05-07-30-012.
Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.
During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift
can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same
torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band
applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in
the transfer case.
This is a normal condition. No repairs should be attempted.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Parking Pawl, A/T >
Component Information > Technical Service Bulletins > A/T - Grinding/Growling Noise in Park on Incline
Parking Pawl: Technical Service Bulletins A/T - Grinding/Growling Noise in Park on Incline
INFORMATION
Bulletin No.: 99-07-30-030F
Date: May 01, 2008
Subject: Grinding and/or Growling Noise in Park on Incline
Models: 2009 and Prior Passenger Cars and Light Duty Trucks (Including Saturn)
with Hydra-Matic Front Wheel Drive (FWD) Automatic Transmissions
Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number
99-07-30-030E (Section 07 - Transmission/Transaxle).
Service Information
Owners of some vehicles equipped with Hydra-Matic front wheel drive transaxles may comment on
a grinding and/or growling noise that is noticeable when standing in PARK on a hill or slope with
the engine running and the parking brake not applied. Under these conditions, the weight of the
vehicle puts a load on the parking pawl which can create a "ground-out" path through the drive
axles, front struts, springs and spring towers. Normal engine noise can be transmitted to the
passenger compartment through the "ground-out" path.
Owners concerned about this condition should be advised to apply the parking brake prior to
shifting into PARK. This is the recommended procedure described in the Owners Manual. Applying
the parking brake first will put the load of the vehicle on the rear brakes rather than on the parking
pawl.
Refer the owner to the appropriate Owner Manual for additional details and instructions.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Locations > Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Locations > Component Locations > Page
6180
RH Side Of Steering Column
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Locations > Component Locations > Page
6181
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and
Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and
Instructions > Page 6184
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Instructions > Page 6185
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and
Instructions > Page 6186
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and
Instructions > Page 6187
Fig.2-Symbols (Part 2 Of 3)
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Instructions > Page 6188
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sensors and Switches A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and
Instructions > Page 6189
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Instructions > Page 6190
Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Instructions > Page 6191
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Instructions > Page 6192
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Instructions > Page 6193
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Instructions > Page 6194
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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Instructions > Page 6195
1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Instructions > Page 6196
Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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Instructions > Page 6197
FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Instructions > Page 6198
Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Instructions > Page 6200
Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Instructions > Page 6201
Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Instructions > Page 6202
Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Instructions > Page 6210
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Instructions > Page 6211
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Instructions > Page 6212
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Instructions > Page 6213
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Instructions > Page 6214
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Instructions > Page 6215
Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Instructions
Transmission Temperature Sensor/Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Instructions > Page 6221
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Instructions > Page 6222
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Instructions > Page 6223
Fig.1-Symbols (Part 1 Of 3)
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Instructions > Page 6224
Fig.2-Symbols (Part 2 Of 3)
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Instructions > Page 6225
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Instructions > Page 6226
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Instructions > Page 6227
Transmission Temperature Sensor/Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Instructions > Page 6228
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Instructions > Page 6229
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Instructions > Page 6231
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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Instructions > Page 6232
1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Instructions > Page 6247
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Instructions > Page 6248
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Instructions > Page 6249
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Instructions > Page 6250
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Instructions > Page 6251
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Instructions > Page 6252
Transmission Range Switch Assembly.
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Transmission Temperature Sensor/Switch: Description and Operation
The Transmission Fluid Temperature (TFT) sensor is a thermistor (a device that changes
resistance according to changes in temperature) used to indicate transmission fluid temperature.
High sensor resistance produces high signal input voltage which corresponds to low fluid
temperature. Low sensor resistance produces low signal input voltage which corresponds to high
fluid temperature. The Powertrain Control Module (PCM) uses the TFT sensor signal input to
determine the following:
^ Torque Converter Clutch (TCC) apply and release schedules.
^ Hot mode determination.
^ Shift quality.
The TFT sensor is part of the transmission range fluid pressure switch assembly and is attached to
the control valve body within the transmission. A fault in the Transmission Fluid Temperature (TFT)
sensor circuit will set a DTC 58. 59 or 79.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Locations
Shift Interlock: Locations
LH Side Of Instrument Panel
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Component Information > Locations > Page 6257
Center Of Instrument Panel Wiring
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Component Information > Diagrams > Diagram Information and Instructions
Shift Interlock: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Component Information > Diagrams > Diagram Information and Instructions > Page 6262
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Component Information > Diagrams > Diagram Information and Instructions > Page 6265
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Component Information > Diagrams > Diagram Information and Instructions > Page 6266
Shift Interlock: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Component Information > Diagrams > Diagram Information and Instructions > Page 6267
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Diagrams > Diagram Information and Instructions > Page 6287
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Diagrams > Diagram Information and Instructions > Page 6288
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Diagrams > Diagram Information and Instructions > Page 6289
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Diagrams > Diagram Information and Instructions > Page 6290
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Diagrams > Diagram Information and Instructions > Page 6291
Brake Transmission Shift Interlock (BTSI)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Diagrams > Page 6292
Shift Interlock: Description and Operation
The Backup Lamp Transmission Position Sensor Switch receives Ignition voltage from I/P Fuse
#12 in "RUN," "BULB TEST" and "START." When the Transmission Shift Lever is in "PARK," the
switch relays voltage to the Brake Transmission Shift Interlock (BTSI) Switch. The BTSI Switch is
normally closed, providing voltage to the BTSI Solenoid, which is permanently grounded at G200.
When the BTSI Solenoid receives voltage, it is energized and prevents the Transmission Shift
Lever from being moved out of "PARK." When the brake pedal is depressed, the BTSI Switch
opens, removing voltage from the BTSI Solenoid. This de-energizes the Solenoid, allowing
operation of the Shift Lever.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Testing and Inspection > Initial Inspection and Diagnostic Overview
Shift Interlock: Initial Inspection and Diagnostic Overview
Circuit Operation - Brake Transaxle Shift Interlock
The Backup Lamp Transmission Position Sensor Switch receives Ignition voltage from I/P Fuse
#12 in "RUN," "BULB TEST" and "START." When the Transmission Shift Lever is in "PARK," the
switch relays voltage to the Brake Transmission Shift Interlock (BTSI) Switch. The BTSI Switch is
normally closed, providing voltage to the BTSI Solenoid, which is permanently grounded at G200.
When the BTSI Solenoid receives voltage, it is energized and prevents the Transmission Shift
Lever from being moved out of "PARK." When the brake pedal is depressed, the BTSI Switch
opens, removing voltage from the BTSI Solenoid. This de-energizes the Solenoid, allowing
operation of the Shift Lever.
Troubleshooting Hints - Brake Transaxle Shift Interlock
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Check I/P Fuse Block Fuse #12. If open, check CKT 239, CKT 275 and CKT 924 for a short to
ground. 2. Make sure G200 is clean and tight. 3. If Transmission Shift Lever does not shift out of
Park, make sure the linkage is properly adjusted. ^
Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
^ Refer to System Diagnosis. See: Component Tests and General Diagnostics
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 6295
Shift Interlock: Symptom Related Diagnostic Procedures
Symptom Table
Chart #1 TRANS Does Not Shift Out Of Park W/Brake Pedal Depressed
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Interlock, A/T >
Component Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 6296
Chart #2 TRANS Shifts Out Of Park With Ignition Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Shift Linkage, A/T >
Component Information > Adjustments
Shift Linkage: Adjustments
Fig.6 Shift Linkage Adjustment.
ADJUSTMENTS
1. Loosen swivel clamp screw. 2. Position shift lever in neutral gate. 3. Position transmission lever
in neutral detent. 4. While holding swivel clamp flush against equalizer lever, tighten swivel clamp
screw, Fig. 6. Do not exert force in either direction on rod or
equalizer lever while tightening swivel clamp screw.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sun Gear > Component
Information > Technical Service Bulletins > Customer Interest for Sun Gear: > 00-07-30-022D > Jun > 08 > A/T - 4L60/65E,
No Reverse/2nd or 4th Gear
Sun Gear: Customer Interest A/T - 4L60/65E, No Reverse/2nd or 4th Gear
TECHNICAL
Bulletin No.: 00-07-30-022D
Date: June 10, 2008
Subject: No Reverse, Second Gear or Fourth Gear (Replace Reaction Sun Shell with More Robust
Heat Treated Parts)
Models: 1993 - 2005 GM Passenger Cars and Light Duty Trucks 2003 - 2005 HUMMER H2
with 4L60/65-E Automatic Transmission (RPOs M30 or M32)
Supercede: This bulletin is being revised to add 2005 model year to the parts information. Please
discard Corporate Bulletin Number 00-07-30-022C (Section 07 - Transmission/Transaxle).
Condition
Some customers may comment on a no reverse, no second or no fourth gear condition. First and
third gears will operate properly.
Cause
The reaction sun gear (673) may not hold inside the reaction sun shell (670).
Correction
Important:
There are FOUR distinct groups of vehicles and repair procedures involved. Vehicles built in the
2001 model year and prior that make use of a reaction shaft to shell thrust washer:
^ The sun shell can be identified by four square holes used to retain the thrust washer. Use
reaction sun shell P/N 24228345, reaction carrier to shell thrust washer (699B) P/N 8642202 and
reaction sun gear shell thrust washer (674) P/N 8642331er (674) P/N 8642331along with the
appropriate seals and washers listed below.
^ Vehicles built in the 2001 model year and prior that have had previous service to the reaction sun
shell: It is possible that some 2001 and prior model year vehicles have had previous service to the
reaction sun shell. At the time of service, these vehicles may have been updated with a Reaction
Sun Shell Kit (Refer to Service Bulletin 020730003) without four square holes to retain the thrust
washer. If it is found in a 2001 model year and prior vehicles that the reaction sun shell DOES NOT
have four square holes to retain the thrust washer, these vehicles must be serviced with P/Ns
24229825 (674), 24217328 and 8642331 along with the appropriate seals and washers listed
below.
^ Vehicles built in the 2001 model year and later that make use of a reaction shaft to shell thrust
bearing: The sun shell can be identified by no holes to retain the thrust washer. Use reaction sun
shell, P/N 24229825, reaction carrier shaft to shell thrust bearing (669A), P/N 24217328 and
reaction sun gear shell thrust washer (674), P/N 8642331 along with the appropriate seals and
washers listed below.
^ Vehicles built from November, 2001 through June, 2002: These vehicles should have the reaction
carrier shaft replaced when the sun shell is replaced. Use shell kit P/N 24229853, which contains a
sun shell (670), a reaction carrier shaft (666), a reaction carrier shaft to shell thrust bearing (669A)
and a reaction sun gear shell thrust washer (674). The appropriate seals and washers listed below
should also be used.
When servicing the transmission as a result of this condition, the transmission oil cooler and lines
MUST be flushed. Refer to Corporate Bulletin Number 02-07-30-052.
Follow the service procedure below for diagnosis and correction of the no reverse, no second, no
forth condition.
Important:
If metallic debris is found on the transmission magnet, the transmission must be completely
disassembled and cleaned. Metallic debris is defined as broken parts and pieces of internal
transmission components. This should not be confused with typical "normal" fine particles found on
all transmission magnets. Failure to properly clean the transmission case and internal components
may lead to additional repeat repairs.
1. Remove the transmission oil pan and inspect the magnet in the bottom of the pan for metal
debris. Refer to SI Document ID # 825141.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sun Gear > Component
Information > Technical Service Bulletins > Customer Interest for Sun Gear: > 00-07-30-022D > Jun > 08 > A/T - 4L60/65E,
No Reverse/2nd or 4th Gear > Page 6308
2. Remove the transmission from the vehicle. Refer to the appropriate SI document.
Important:
^ Inspect all the transmission components for damage or wear. Replace all damaged or worn
components. The parts shown above should be sufficient to correct this concern.
^ This condition does not normally require replacement of the transmission completely.
Components such as clutches, valve body, pump and torque converters will NOT require
replacement to correct this condition.
Disassemble the transmission and replace the appropriate parts listed below. Refer to the Unit
Repair Manual - Repair Instructions.
3. Reinstall the transmission in the vehicle. Refer to appropriate service information.
When servicing the transmission as a result of this condition, the transmission oil cooler and lines
MUST be flushed. Refer to Corporate Bulletin Number 02-07-30-052.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sun Gear > Component
Information > Technical Service Bulletins > Customer Interest for Sun Gear: > 00-07-30-022D > Jun > 08 > A/T - 4L60/65E,
No Reverse/2nd or 4th Gear > Page 6309
Parts Information
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sun Gear > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Sun Gear: > 00-07-30-022D > Jun > 08 > A/T
- 4L60/65E, No Reverse/2nd or 4th Gear
Sun Gear: All Technical Service Bulletins A/T - 4L60/65E, No Reverse/2nd or 4th Gear
TECHNICAL
Bulletin No.: 00-07-30-022D
Date: June 10, 2008
Subject: No Reverse, Second Gear or Fourth Gear (Replace Reaction Sun Shell with More Robust
Heat Treated Parts)
Models: 1993 - 2005 GM Passenger Cars and Light Duty Trucks 2003 - 2005 HUMMER H2
with 4L60/65-E Automatic Transmission (RPOs M30 or M32)
Supercede: This bulletin is being revised to add 2005 model year to the parts information. Please
discard Corporate Bulletin Number 00-07-30-022C (Section 07 - Transmission/Transaxle).
Condition
Some customers may comment on a no reverse, no second or no fourth gear condition. First and
third gears will operate properly.
Cause
The reaction sun gear (673) may not hold inside the reaction sun shell (670).
Correction
Important:
There are FOUR distinct groups of vehicles and repair procedures involved. Vehicles built in the
2001 model year and prior that make use of a reaction shaft to shell thrust washer:
^ The sun shell can be identified by four square holes used to retain the thrust washer. Use
reaction sun shell P/N 24228345, reaction carrier to shell thrust washer (699B) P/N 8642202 and
reaction sun gear shell thrust washer (674) P/N 8642331er (674) P/N 8642331along with the
appropriate seals and washers listed below.
^ Vehicles built in the 2001 model year and prior that have had previous service to the reaction sun
shell: It is possible that some 2001 and prior model year vehicles have had previous service to the
reaction sun shell. At the time of service, these vehicles may have been updated with a Reaction
Sun Shell Kit (Refer to Service Bulletin 020730003) without four square holes to retain the thrust
washer. If it is found in a 2001 model year and prior vehicles that the reaction sun shell DOES NOT
have four square holes to retain the thrust washer, these vehicles must be serviced with P/Ns
24229825 (674), 24217328 and 8642331 along with the appropriate seals and washers listed
below.
^ Vehicles built in the 2001 model year and later that make use of a reaction shaft to shell thrust
bearing: The sun shell can be identified by no holes to retain the thrust washer. Use reaction sun
shell, P/N 24229825, reaction carrier shaft to shell thrust bearing (669A), P/N 24217328 and
reaction sun gear shell thrust washer (674), P/N 8642331 along with the appropriate seals and
washers listed below.
^ Vehicles built from November, 2001 through June, 2002: These vehicles should have the reaction
carrier shaft replaced when the sun shell is replaced. Use shell kit P/N 24229853, which contains a
sun shell (670), a reaction carrier shaft (666), a reaction carrier shaft to shell thrust bearing (669A)
and a reaction sun gear shell thrust washer (674). The appropriate seals and washers listed below
should also be used.
When servicing the transmission as a result of this condition, the transmission oil cooler and lines
MUST be flushed. Refer to Corporate Bulletin Number 02-07-30-052.
Follow the service procedure below for diagnosis and correction of the no reverse, no second, no
forth condition.
Important:
If metallic debris is found on the transmission magnet, the transmission must be completely
disassembled and cleaned. Metallic debris is defined as broken parts and pieces of internal
transmission components. This should not be confused with typical "normal" fine particles found on
all transmission magnets. Failure to properly clean the transmission case and internal components
may lead to additional repeat repairs.
1. Remove the transmission oil pan and inspect the magnet in the bottom of the pan for metal
debris. Refer to SI Document ID # 825141.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sun Gear > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Sun Gear: > 00-07-30-022D > Jun > 08 > A/T
- 4L60/65E, No Reverse/2nd or 4th Gear > Page 6315
2. Remove the transmission from the vehicle. Refer to the appropriate SI document.
Important:
^ Inspect all the transmission components for damage or wear. Replace all damaged or worn
components. The parts shown above should be sufficient to correct this concern.
^ This condition does not normally require replacement of the transmission completely.
Components such as clutches, valve body, pump and torque converters will NOT require
replacement to correct this condition.
Disassemble the transmission and replace the appropriate parts listed below. Refer to the Unit
Repair Manual - Repair Instructions.
3. Reinstall the transmission in the vehicle. Refer to appropriate service information.
When servicing the transmission as a result of this condition, the transmission oil cooler and lines
MUST be flushed. Refer to Corporate Bulletin Number 02-07-30-052.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Sun Gear > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Sun Gear: > 00-07-30-022D > Jun > 08 > A/T
- 4L60/65E, No Reverse/2nd or 4th Gear > Page 6316
Parts Information
Warranty Information
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Torque Converter >
Component Information > Technical Service Bulletins > A/T - Torque Converter Replacement Information
Torque Converter: Technical Service Bulletins A/T - Torque Converter Replacement Information
INFORMATION
Bulletin No.: 01-07-30-010C
Date: May 12, 2008
Subject: Automatic Transmission/Transaxle Torque Converter Replacement
Models: 2009 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2, H3 2009
and Prior Saturn Cars and Light Duty Trucks (Except VTi Equipped Vehicles (RPO M16 and M75)
2009 and Prior Saab 9-7X
with ALL Automatic Transmissions and Transaxles
Supercede:
This bulletin is being revised to add the 2007-2009 model years. Please discard Corporate Bulletin
Number 01-07-30-010B (Section 07 - Transmission/Transaxle).
The purpose of this bulletin is to help technicians determine when a torque converter should be
replaced. Below is a list of general guidelines to follow.
The converter should NOT be replaced if the following apply:
^ DTC P0742 - TCC stuck on is set. This code is almost always the result of a controls condition
(i.e. stuck TCC solenoid/valve). Experience has shown that this code rarely indicates a mechanical
concern within the torque converter.
^ The fluid has an odor or is discolored but no evidence of metal contamination.
^ Fine metal particles (traces of metal flakes/gray color to fluid ) are found in the converter. This is
not harmful to the torque converter.
^ The vehicle has been exposed to high mileage.
^ A small amount of wear appears on the hub where the oil pump drive gear mates to the converter
(RWD only). A certain amount of such wear is normal for both the hub and oil pump gear. Neither
the converter nor the front pump assembly should be replaced.
The torque converter should be replaced under any of the following conditions:
^ The vehicle has TCC shudder and/or no TCC apply. First complete all electrical and hydraulic
diagnosis and check for proper engine operation. The converter clutch may be damaged. Also the
converter bushing and/or internal 0-ring may be damaged.
^ Evidence of damage to the oil pump assembly pump shaft turbine shaft drive sprocket support
and bearing or metal chips/debris in the converter.
^ Metal chips/debris are found in the converter or when flushing the cooler and the cooler lines.
^ External leaks in the hub weld area lug weld or closure weld.
^ Converter pilot is broken damaged or fits poorly into the crankshaft.
^ The converter hub is scored or damaged.
^ The transmission oil is contaminated with engine coolant engine oil or water.
^ If excessive end play is found after measuring the converter for proper end play (refer to Service
Manual).
^ If metal chips/debris are found in the fluid filter or on the magnet and no internal parts in the unit
are worn or damaged. This indicates that the material came from the converter.
^ The converter has an unbalanced condition that results in a vibration that cannot be corrected by
following Converter Vibration Procedures.
^ Blue converter or dark circular ring between lugs. This condition will also require a complete
cleaning of the cooler and a check for adequate flow
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Torque Converter >
Component Information > Technical Service Bulletins > A/T - Torque Converter Replacement Information > Page 6321
through the cooler.
^ Converter bearing noise determined by noise from the bell housing area in Drive or Reverse at
idle. The noise is gone in Neutral and Park.
^ If silicon from the viscous clutch is found in the lower pan (4T80-E ONLY).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Torque Converter
Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch
Friction/Plates
Torque Converter Clutch Solenoid: Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4
Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Torque Converter
Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch
Friction/Plates > Page 6326
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Torque Converter
Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch
Friction/Plates > Page 6327
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Torque Converter
Clutch Solenoid, A/T > Component Information > Technical Service Bulletins > Page 6328
Torque Converter Clutch Solenoid: Service and Repair
REPLACE
1. Raise and support vehicle. 2. Disconnect heated oxygen sensor. 3. Remove catalytic converter
to muffler attaching bolts and nuts. 4. Remove catalytic converter hanger to catalytic converter
bolts. 5. Remove righthand side dampener assembly. 6. Remove nuts holding exhaust pipe to
exhaust manifold. 7. Remove converter and pipe assembly from vehicle. 8. Remove oil pan and oil
filter assembly. 9. Disconnect external wiring harness from transmission pass through connector.
10. Remove accumulator cover attaching bolts. 11. Remove 1-2 accumulator cover, piston and
spring. 12. Disconnect electrical connectors. 13. Remove pressure control solenoid retainer bolt,
then the retainer and solenoid. 14. Remove TCC solenoid retaining bolts. 15. Remove
pass-through electrical connector from transmission case by positioning the small end of power
piston seal protector and diaphragm
retainer installer tool No. J-28458 or equivalent, over the top of the connector, then twist tool to
release the four tabs while at the same time pulling the harness through the case.
16. Remove TCC solenoid with wiring harness from transmission case. 17. Reverse procedure to
install, noting the following:
a. Tighten TCC solenoid retaining bolt to specification. b. Tighten pressure control solenoid
retaining bolt to specification. c. When installing 1-2 accumulator piston to accumulator cover, the
piston legs must face towards the case. d. Tighten accumulator attaching bolts to specification
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Cooler,
A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush
Transmission Cooler: Technical Service Bulletins A/T - Fluid Oil Cooler Flush
INFORMATION
Bulletin No.: 02-07-30-052G
Date: March 02, 2011
Subject: Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096
TransFlow(R)
Models:
2011 and Prior Passenger Cars and Light Duty Trucks 2003-2010 HUMMER H2 2006-2010
HUMMER H3 with Automatic Transmission/Transaxle including Allison(R) Transmissions
Supercede: This bulletin is being revised to update the model years. Please discard Corporate
Bulletin Number 02-07-30-052F (Section 07 - Transmission/Transaxle).
Important All labor operations that include removal of the transmission from the vehicle include
labor time to flush the transmission oil cooler system.
The J 45096 transmission oil cooling system flush and flow test tool replaces current tool J
35944-A. J 45096 is a self-contained unit utilizing a 12-volt flow meter, shop air supply and
DEXRON(R) VI automatic transmission fluid (ATF). In the flush mode, transmission fluid is cycled
through the transmission oil cooling system. High-pressure air is automatically injected into the fluid
stream adding agitation to the ATF oil to enhance the removal of contaminated ATF oil and debris.
In the flow mode, an electronic flow meter is used to measure the flow capability of the ATF oil
cooling system. A digital display indicates the ATF oil flow rate in gallons per minute (GPM) along
with the amount of ATF oil in the supply vessel, supply vessel ATF oil temperature, machine cycles
and the operating mode. The supply oil vessel has 30 L (32 qt) capacity and the waste oil vessel
has 32 L (34 qt) capacity. The waste oil vessel is constructed of a translucent composite material
that allows the user to easily identify the oil level. The waste oil vessel can accommodate vacuum
evacuation and gravity draining. In the code mode, a random, encrypted code is generated that can
be used for verification of flow test results.
Current essential cooler line adapters are used to connect the J 45096 to the automatic
transmission oil cooler lines that allows J 45096 to adapt to General Motors passenger cars and
light duty trucks, current and past models (except the Pontiac Vibe, Wave and Chevrolet Aveo).
The tool may be adapted for use on the Pontiac Vibe, Wave and Chevrolet Aveo by dealership
personnel with a barbed hose connector and rubber hose obtained locally. The
Vibe's/Wave's/Aveo's transmission has a transmission oil requirement which is slightly different
than DEXRON(R) VI ATF. However, flushing the cooler with DEXRON(R) VI automatic
transmission fluid is an acceptable service procedure. Very little fluid remains in the cooler after the
flush procedure and the residual DEXRON(R) VI ATF in the cooler is compatible with the
Vibe's/Wave's/Aveo's transmission fluid.
Notice
Insufficient oil flow through the ATF oil cooling system will cause premature transmission failure.
The required minimum ATF oil flow rate reading is directly related to the supply oil temperature.
Refer to the flow rate reference chart for the oil flow rate specification based on the temperature of
the ATF in the supply vessel.
Helpful Hints for Maintaining the Temperature at or above 18°C (65°F)
Important
- The temperature of the supply vessel oil must be 18°C (65°F) or greater for J 45096 to operate. It
is recommended to store the J 45096 in an area of the dealership where the room temperature
remains at or above 18°C (65°F) when not in use.
- Do not attempt to increase the fluid temperature in the Transflow(R) machine with an engine oil
dipstick, or any other immersion type heater. The Transflow(R) machine has a check valve in the
supply reservoir. Inserting a heater will damage the check valve and the subsequent repair
expense would be the dealer's responsibility.
- A heater blanket, P/N J-45096-10, is available for the Transflow(R) transmission cooling system
flushing tool. This heater fastens around the Transflow(R) internal supply vessel and runs on 110
volts AC. The heater will warm the ATF in the supply vessel to at least 18°C (65° F) and has a
thermostat to hold a constant temperature.
Store the Transmission Cooling System Service Tool, J 45096, Transflow(R) machine in a room
where the temperature is maintained at or above 18°C (65°F).
Keep the ATF level in the reservoir low when the Transmission Cooling System Service Tool, J
45096, Transflow(R), is not in use. Store several gallons of oil in an area where the temperature is
maintained at or above 18°C (65°F). Fill the reservoir of the J 45096 as needed before using the
machine on
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Cooler,
A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush > Page 6333
each repair.
With the ATF in a tightly sealed container, place the container in a tub of hot water for a period of
time. Then pour the ATF into the reservoir. This method works best with a low fluid level in the
reservoir.
Place the Transflow(R) machine in the direct sunlight with the cabinet door open to expose the
reservoir to the rays of the warm sun.
Flush / Flow Test Procedure
Important All labor operations that include removal of the transmission from the vehicle and require
the transmission oil pan or transmission side cover to be removed include labor time to flush the
transmission oil cooler system.
Refer to SI for Automatic Transmission Oil Cooler Flushing and Flow Test J 45096 for the
appropriate procedure.
Important The J 45096 can be used to flush the transmission oil cooler system on an Allison
equipped vehicle, but the flow meter should not be utilized. Refer to SI for Automatic Transmission
Oil Cooler Flushing and Flow Test J 45096 for the appropriate flow check procedure.
Machine Displays
After completion of the flush and flow test, the following information is to be recorded on the repair
order. This information is displayed on the Transmission Cooling System Service Tool, J 45096,
Transflow(R) machine when the dial is in the code position.
- Tested flow rate (displayed in Gallons Per Minute (GPM)
- Temperature (displayed is degrees Fahrenheit)
- Cycle number (a number)
- Seven digit Alpha/Numeric flow code (i.e. A10DFB2)
Warranty Information
Important All labor operations that include removal of the transmission from the vehicle include
labor time to flush the transmission oil cooler system.
Performing a transmission oil cooling system flush and flow test will use between 4.7-7.5 L (5-8 qts)
of DEXRON(R)VI transmission fluid. The amount
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Cooler,
A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush > Page 6334
of transmission fluid (ATF), (DEXRON(R)VI) (fluid) that is to be charged for the flush portion of the
repair should not exceed the allowable charge for 7.5 L (2 gal) of fluid. This expense should be
shown in the Parts Section of the warranty claim document.
The Seven digit Alpha/Numeric flow code, i.e. A10DFB2, "MUST" be written on the job card and
placed in the comments section of the warranty claim. Any repair that requires the technician to
contact the Product Quality Center (PQC) must also include the seven digit flow code. The agent
will request the seven digit flow code and add the information to the PQC case prior to providing
authorization for the warranty claim.
The Seven digit Alpha/Numeric flow code, i.e. A10DFB2, "MUST" be written on the job card,
entered in the warranty claim labor operation Flush Code additional field (when available) and
placed in the comments section of the warranty claim. Any repair that requires the technician to
contact the Product Quality Center (PQC) must also include the seven digit flow code. The agent
will request the seven digit flow code and add the information to the PQC case prior to providing
authorization for the warranty claim.
Disclaimer
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Cooler,
A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush > Page 6335
Transmission Cooler: Technical Service Bulletins A/T - Water Or Coolant Contamination
Information
INFORMATION
Bulletin No.: 08-07-30-035B
Date: November 01, 2010
Subject: Information on Water or Ethylene Glycol in Transmission Fluid
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks with Automatic Transmission
Supercede: This bulletin is being revised to update model years. Please discard Corporate Bulletin
Number 08-07-30-035A (Section 07 - Transmission/Transaxle).
Water or ethylene glycol in automatic transmission fluid (ATF) is harmful to internal transmission
components and will have a negative effect on reliability and durability of these parts. Water or
ethylene glycol in ATF will also change the friction of the clutches, frequently resulting in shudder
during engagement or gear changes, especially during torque converter clutch engagement.
Indications of water in the ATF may include:
- ATF blowing out of the transmission vent tube.
- ATF may appear cloudy or, in cases of extreme contamination, have the appearance of a
strawberry milkshake.
- Visible water in the oil pan.
- A milky white substance inside the pan area.
- Spacer plate gaskets that appear to be glued to the valve body face or case.
- Spacer plate gaskets that appear to be swollen or wrinkled in areas where they are not
compressed.
- Rust on internal transmission iron/steel components.
If water in the ATF has been found and the source of the water entry has not been identified, or if a
leaking in-radiator transmission oil cooler is suspected (with no evidence of cross-contamination in
the coolant recovery reservoir), a simple and quick test kit is available that detects the presence of
ethylene glycol in ATF. The "Gly-Tek" test kit, available from the Nelco Company, should be
obtained and the ATF tested to make an accurate decision on the need for radiator replacement.
This can help to prevent customer comebacks if the in-radiator transmission oil cooler is leaking
and reduce repair expenses by avoiding radiator replacement if the cooler is not leaking. These
test kits can be obtained from:
Nelco Company
Test kits can be ordered by phone or through the website listed above. Orders are shipped
standard delivery time but can be shipped on a next day delivery basis for an extra charge. One
test kit will complete 10 individual fluid sample tests. For vehicles repaired under warranty, the cost
of the complete test kit plus shipping charges should be divided by 10 and submitted on the
warranty claim as a net item.
The transmission should be repaired or replaced based on the normal cost comparison procedure.
Important If water or coolant is found in the transmission, the following components MUST be
replaced.
- Replace all of the rubber-type seals.
- Replace all of the composition-faced clutch plates and/or bands.
- Replace all of the nylon parts.
- Replace the torque converter.
- Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
Important The following steps must be completed when repairing or replacing.
Flush and flow check the transmission oil cooler using J 45096. Refer to Corporate Bulletin Number
02-07-30-052F- Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096
TransFlow.
- Thoroughly inspect the engine cooling system and hoses and clean/repair as necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush > Page 6336
Disclaimer
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Cooler,
A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush > Page 6337
Transmission Cooler: Technical Service Bulletins A/T - Oil Cooler Flushing Frequently Asked
Questions
File In Section: 07 - Transmission/Transaxle
Bulletin No.: 03-07-30-027
Date: June, 2003
INFORMATION
Subject: Most Frequently Asked Questions and Answers for J 45096 TransFlow Transmission Oil
Cooling System Flushing Machine
Models: 2004 and Prior Passenger Cars and Light Duty Trucks with Automatic
Transmission/Transaxle
2004 and Prior HUMMER H2
This bulletin is issued to help answer the most frequently asked questions and concerns about
essential tool J 45096.
Q: Why doesn't the machine work below 18°C (65°F)?
A: The flow characteristics of ATF at temperatures below 18°C (65°F) does not provide accurate
flow test results with the electronics used in the J
45096.
Q: Why didn't the unit come with a tank heater?
A: The vast majority of dealerships do not require a heater to keep the ATF above 18°C (65°F). As
a result, the heater was deleted as a cost-savings
measure. A tank heater, J 45096-10, is currently available from Kent-Moore if your dealership
requires it. Refer to Corporate Bulletin Number 03-07-30-002A for suggestions on warming the ATF
without using a heater blanket.
Q: Why does the machine fail new oil coolers?
A: Several reasons have been found. The most likely reason is the air pressure at the air hose
connected to the J 45096 is less than 586 kPa (85 psi).
Other reasons include a twisted hose inside the J 45096 at the bulkhead as a result of the nut
turning when the waste or supply hose was installed, the internal pressure regulator was
improperly set at the factory or a problem with the cooler lines on the vehicle. Perform the J 45096
self-test as described on pages 9 and 10 of the Operation Manual. If a problem is still detected,
refer to Troubleshooting on page 19 of the Operation Manual. If a problem still persists, contact
Kent-Moore Customer Service at 1-800-345-2233.
Q: What is the difference between steel and aluminum oil coolers?
A: The aluminum oil cooler tube is slightly thinner in construction than the steel oil cooler tube,
which affects the oil flow rate. The fitting that is
protruding out of the radiator tank easily identifies the aluminum oil cooler. Refer to the Quick
Reference card provided with the J 45096 in order to identify the proper flow rate for the aluminum
oil cooler.
Q: Why can't I use TransFlow for Allison transmission cooling Systems?
A: Validation of TransFlow is currently under development for light duty trucks equipped with the
Allison automatic transmission. TransFlow is based
on the existing MINIMUM flow rate specification through the transmission oil cooling system. The
Allison transmission oil cooling system only has MAXIMUM oil flow rates specified and J 45096
does not have the capability to test the transmission oil cooling system at the maximum oil flow rate
specification.
Q: Why doesn't GM publish a specification for auxiliary transmission oil coolers?
A: The auxiliary oil cooler used with GM vehicles does not contain an internal turbulator plate like
the radiator tank oil cooler does. Therefore, there is
no internal restriction that would affect the flow rate through the oil cooling system so a
specification for auxiliary oil cooler is not required. Keep in mind, kinks and damage to the auxiliary
cooler and lines can affect the flow rate through the system.
Q: Why did GM drop the labor time for transmission repairs?
A: The labor for flushing and flow testing the transmission oil cooling system is included with the
R&R; labor of the "K" labor operations that require
transmission removal. The time required to use the J 45096 to perform the flush and flow test is
much less than that of the J 35944-A. The warranty labor savings allowed GM to provide the J
45096 at no cost to dealerships.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Cooler,
A/T > Component Information > Technical Service Bulletins > A/T - Fluid Oil Cooler Flush > Page 6338
Q: Why didn't the machine come with the adapters to hook up to the car?
A: The J 45096 was designed to use the previously released essential cooler line adapters for the J
35944-A. All adapters are listed on page 17 of the
Operation Manual and can be ordered from Kent-Moore at 1-800-345-2233.
Q: How do I connect the J 45096 to a Catera, Prizm or a Vibe?
A: These vehicles, along with many other models, only require barbed fittings to connect to the
rubber cooler hose. These fittings are commercially
available and already found in many shops.
Q: Why didn't I receive an Operation Manual with the machine?
A: The Operation Manual was packaged in the upper portion of the shipping carton. If the shipping
carton was lifted off the base without opening the
top of the carton, the Operation Manual could have been discarded with the carton. Replacement
Operation Manual packages can be obtained from Kent-Moore Customer Service at
1-800-345-2233.
Q: Why can't I re-use the transmission fluid I use for flushing?
A: The very fine metal and clutch material debris from the transmission failure in the ATF causes
failures with the hall effect speed sensors that are used
to measure the flow rate. To avoid costly repairs, expensive filters, regular maintenance and
problems caused by a partially restricted filter, the filter was not included.
Q: What do I do if I need service on my machine?
A: Call Kent-Moore Customer Service at 1-800-345-2233. The J 45096 has a one-year warranty.
Q: Can I flush and flow engine oil coolers?
A: The engine oil cooler flow rates, the appropriate adapters and an acceptable procedure are
currently under development.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Position
Switch/Sensor, A/T > Component Information > Locations > Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Position
Switch/Sensor, A/T > Component Information > Locations > Component Locations > Page 6343
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Position
Switch/Sensor, A/T > Component Information > Locations > Component Locations > Page 6344
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission Position
Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6347
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6348
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6349
Fig.1-Symbols (Part 1 Of 3)
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6350
Fig.2-Symbols (Part 2 Of 3)
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6351
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6352
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6353
Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6354
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6369
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6372
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6373
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6374
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6375
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6376
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6377
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Switch/Sensor, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page 6378
Park/Neutral Position Switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Switch/Sensor, A/T > Component Information > Diagrams > Page 6379
Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions
Transmission Temperature Sensor/Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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6387
Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
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Transmission Temperature Sensor/Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6407
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6408
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission
Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6409
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission
Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6410
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6411
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6412
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission
Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6413
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6414
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Transmission
Temperature Sensor/Switch, A/T > Component Information > Diagrams > Diagram Information and Instructions > Page
6415
Transmission Range Switch Assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Temperature Sensor/Switch, A/T > Component Information > Diagrams > Page 6416
Transmission Temperature Sensor/Switch: Description and Operation
The Transmission Fluid Temperature (TFT) sensor is a thermistor (a device that changes
resistance according to changes in temperature) used to indicate transmission fluid temperature.
High sensor resistance produces high signal input voltage which corresponds to low fluid
temperature. Low sensor resistance produces low signal input voltage which corresponds to high
fluid temperature. The Powertrain Control Module (PCM) uses the TFT sensor signal input to
determine the following:
^ Torque Converter Clutch (TCC) apply and release schedules.
^ Hot mode determination.
^ Shift quality.
The TFT sensor is part of the transmission range fluid pressure switch assembly and is attached to
the control valve body within the transmission. A fault in the Transmission Fluid Temperature (TFT)
sensor circuit will set a DTC 58. 59 or 79.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Automatic Transmission/Transaxle > Valve Body, A/T >
Component Information > Technical Service Bulletins > A/T Control - DTC P0756 Diagnostic Tips
Valve Body: Technical Service Bulletins A/T Control - DTC P0756 Diagnostic Tips
INFORMATION
Bulletin No.: 01-07-30-036H
Date: January 29, 2009
Subject: Diagnostic Tips for Automatic Transmission DTC P0756, Second, Third, Fourth Gear Start
Models: 2009 and Prior GM Passenger Cars and Light Duty Trucks 2009 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
with 4L60-E, 4L65-E or 4L70E Automatic Transmission (RPOs M30, M32 or M70)
Supercede:
This bulletin is being revised to add the 2009 model year and add details regarding spacer plates.
Please discard Corporate Bulletin Number 01-07-30-036G (Section 07 - Transmission/Transaxle).
Some dealership technicians may have difficulty diagnosing DTC P0756, 2-3 Shift Valve
Performance on 4L60-E, 4L65-E or 4L70E automatic transmissions. As detailed in the Service
Manual, when the PCM detects a 4-3-3-4 shift pattern, DTC P0756 will set. Some customers may
also describe a condition of a second, third or fourth gear start that may have the same causes but
has not set this DTC yet. Below are some tips when diagnosing this DTC:
^ This is a performance code. This means that a mechanical malfunction exists.
^ This code is not set by electrical issues such as a damaged wiring harness or poor electrical
connections. Electrical problems would cause a DTC P0758, P0787 or P0788 to set.
^ The most likely cause is chips/debris plugging the filtered AFL oil at orifice # 29 on the top of the
spacer plate (48). This is a very small hole and is easily plugged by a small amount of debris. It is
important to remove the spacer plate and inspect orifice # 29 and the immediate area for the
presence of chips/debris. Also, the transmission case passage directly above this orifice and the
valve body passage directly below should be inspected and cleaned of any chips/debris. For 2003
and newer vehicles the spacer plate should be replaced. The service replacement spacer plate is a
bonded style with gaskets and solenoid filter screens bonded to the spacer plate. These screens
can help to prevent plugging of orifice # 29 caused by small debris or chips.
^ This code could be set if the 2-3 shift valve (368) were stuck or hung-up in its bore. Inspect the
2-3 shift valve (368) and the 2-3 shuttle valve (369) for free movement or damage and clean the
valves, the bore and the valve body passages.
^ This code could be set by a 2-3 shift solenoid (367b) if it were cracked, broken or leaking. Refer
to Shift Solenoid Leak Test in the appropriate Service Manual for the leak test procedure. Based on
parts return findings, a damaged or leaking shift solenoid is the least likely cause of this condition.
Simply replacing a shift solenoid will not correct this condition unless the solenoid has been found
to be cracked, broken or leaking.
It is important to also refer to the appropriate Service Manual or Service Information (SI) for further
possible causes of this condition.
Disclaimer
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Clutch, M/T > Clutch Hydraulic System > Clutch Fluid >
Component Information > Specifications > Capacity Specifications
Clutch Fluid: Capacity Specifications
Fill the clutch master cylinder to the "Full" or "MAX" mark on the reservoir. Do not overfill.
Caution: Should accidental spillage occur, rinse the area thoroughly with water. Pay special
attention to any electrical wires, parts, harnesses, rubber or painted surfaces.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Clutch, M/T > Clutch Hydraulic System > Clutch Fluid >
Component Information > Specifications > Capacity Specifications > Page 6427
Clutch Fluid: Fluid Type Specifications
Hydraulic Clutch Fluid
........................................................................................................................................ GM P/N
12345347 or DOT 3 Brake Fluid
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Continuously Variable Transmission/Transaxle, CVT >
Component Information > Technical Service Bulletins > Customer Interest: > 04-07-30-013B > Feb > 07 > Engine, A/T Shift/Driveability Concerns/MIL ON
Continuously Variable Transmission/Transaxle: Customer Interest Engine, A/T - Shift/Driveability
Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
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Component Information > Technical Service Bulletins > Customer Interest: > 04-07-30-013B > Feb > 07 > Engine, A/T Shift/Driveability Concerns/MIL ON > Page 6436
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Continuously Variable Transmission/Transaxle, CVT >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Continuously Variable
Transmission/Transaxle: > 04-06-01-029E > Apr > 10 > Vehicle - Engine Crankcase and Subsystems Flushing Info.
Continuously Variable Transmission/Transaxle: All Technical Service Bulletins Vehicle - Engine
Crankcase and Subsystems Flushing Info.
INFORMATION
Bulletin No.: 04-06-01-029E
Date: April 29, 2010
Subject: Unnecessary Flushing Services, Additive Recommendations and Proper Utilization of GM
Simplified Maintenance Schedule to Enhance Customer Service Experience
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to update the model years and add information about the
proper transmission flush procedure. Please discard Corporate Bulletin Number 04-06-01-029D
(Section 06 - Engine/Propulsion System).
An Overview of Proper Vehicle Service
General Motors is aware that some companies are marketing tools and equipment to support a
subsystem flushing procedures. These dedicated machines are in addition to many engine oil,
cooling system, fuel system, A/C, transmission flush and steering system additives available to the
consumer. GM Vehicles under normal usage do not require any additional procedures or additives
beyond what is advised under the former Vehicle Maintenance Schedules or the current Simplified
Maintenance Schedules. Do not confuse machines available from Kent-Moore/SPX that are
designed to aid and accelerate the process of fluid changing with these flushing machines.
Engine Crankcase Flushing
General Motors Corporation does not endorse or recommend engine crankcase flushing for any of
its gasoline engines. Analysis of some of the aftermarket materials used for crankcase flushing
indicate incompatibility with GM engine components and the potential for damage to some engine
seals and bearings. Damage to engine components resulting from crankcase flushing IS NOT
COVERED under the terms of the New Vehicle Warranty.
GM Authorized Service Information: Detailed, Descriptive, and Complete
If a specific model vehicle or powertrain need is identified, GM will issue an Authorized Service
Document containing a procedure and, if required, provide, make available, or require the specific
use of a machine, tool or chemical to accomplish proper vehicle servicing. An example of this is
fuel injector cleaning. Due to variation in fuel quality in different areas of the country, GM has
recognized the need for fuel injector cleaning methods on some engines, though under normal
circumstances, this service is not part of the maintenance requirements.
GM has published several gasoline fuel injector cleaning bulletins that fully outline the methods to
be used in conjunction with GM Part Numbered solutions to accomplish proper and safe cleaning
of the fuel injectors with preventative maintenance suggestions to maintain optimum performance.
You may refer to Corporate Bulletin Numbers 03-06-04-030 and 04-06-04-051 for additional
information on this subject.
Subsystem Flushing
Flushing of A/C lines, radiators, transmission coolers, and power steering systems are recognized
practices to be performed after catastrophic failures or extreme corrosion when encountered in
radiators. For acceptable A/C flushing concerns, refer to Corporate Bulletin Number 01-01-38-006.
This practice is NOT required or recommended for normal service operations.
The use of external transmission fluid exchange or flush machines is NOT recommended for the
automatic or manual transmission. Use of external machines to replace the fluid may affect the
operation or durability of the transmission. Transmission fluid should only be replaced by draining
and refilling following directions in SI. Refer to Automatic/Manual Transmission Fluid and Filter
Replacement.
Approved Transmission Flushing Tool (Transmission Cooler Only)
The Automatic Transmission Oil Cooler Flush and Flow Test Tool is recommended for GM
vehicles. Refer to Transmission Fluid Cooler Flushing and Flow Test in SI using the J 45096.
Service Is Important to You and Your Customer
General Motors takes great pride in offering our dealerships and customers high quality vehicles
that require extremely low maintenance over the life of the vehicle. This low cost of ownership
builds repeat sales and offers our customers measurable economy of operation against competing
vehicles.
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6442
Providing responsible services at the proper intervals will greatly aid your dealership with repeat
business, and additional services when required. Most customers appreciate and gain trust in the
dealership that informs and offers them just what they need for continued trouble-free operation.
Examine your service department's practices and verify that all Service Consultants and
Technicians focus on customer satisfaction, vehicle inspections, and other products at time of
service. Use this opportunity to upgrade the services you provide to your customers. Here are a
few suggestions:
- Take the time required to align your dealership service practices with the new GM Simplified
Maintenance Schedule. Use the new vehicle Owner's Manual Maintenance I and II schedules to
create a "mirror image" in your advertising and dealer service pricing that is easily understandable
to your customer. Taking advantage of this new service strategy may greatly increase your
dealership service sales and customer retention while decreasing the frequency of visits and
inconvenience to your customer.
- Review your program to ensure that all vehicles coming in are evaluated for safety and wear
items. Examine all vehicles for tire condition, signs of misalignment, brake wear, exterior lamp
functionality, exhaust condition, A/C cooling performance, SRS or Air Bag MIL, along with Service
Engine Soon or Check Engine indicators. If the Service Engine Soon or Check Engine MIL is
illuminated, it is vital that you inform the customer of the concerns with ignoring the indicator and
what the required repair would cost. In addition to the possibility of increased emissions and
driveability concerns, many customers are unaware that lower gas mileage may also result, with
additional cost to the customer.
- Be complete in your service recommendations. Some sales opportunities are not being fully
pursued nationally. Focus on overlooked but required maintenance that has real benefits to the
customer. Many vehicles are equipped with cabin air filters. If these filters are used beyond
replacement time, they may impede airflow decreasing A/C and heating performance. Make sure
these filters are part of your recommended service. Note that some of our vehicles may not have
been factory equipped but will accept the filters as an accessory.
- Express the value in maintaining the finish quality of the customer's vehicle at the Maintenance I
and II visits. More fully utilize the vehicle prep personnel you already have in place. In today's
world, many people simply ignore the finish of their vehicle, at best infrequently using an automatic
car wash for exterior cleaning. Offer vehicle detailing services in stages from just a wash and wax
to a complete interior cleaning. When paired with the Simplified Maintenance visit, this will increase
customer satisfaction. On return, the customer gets a visibly improved vehicle that will be a source
of pride of ownership along with a vehicle that is now fully maintained. Also, reinforce the improved
resale value of a completely maintained vehicle.
- For customers who clean and maintain the appearance of their vehicles themselves encourage
the use of GM Vehicle Care products. Many customers may have never used GM Car Wash/Wax
Concentrate, GM Cleaner Wax or a longtime product, GM Glass Cleaner, which is a favorite of
many customers who try it just once. If your dealership give samples of these products with new
car purchases, customers may already be sold on the product but not willing to make a special trip
to the dealership. Capitalize on sales at this time. Stock shelves right at the Service counter with
these products and consider instituting compensation programs for Service Consultants who
suggest these products. Many consumers faced with an intimidating wall full of car care products
sold at local auto parts stores may find it comforting to purchase a fully tested product sold by GM
that they know will not harm the finish of their vehicle. We suggest these competitively priced basic
vehicle care products to emphasize:
In USA:
- #12378401 GM Vehicle Care Wash/Wax Concentrate 16 fl. oz. (0.473L)
- #89021822 GM Vehicle Care Glass Cleaner Aerosol 18 oz. (510 g)
- #12377966 GM Vehicle Care Cleaner Wax 16 fl. oz. (0.473L)
- #1052929 GM Vehicle Care Chrome and Wire Wheel Cleaner 16 fl. oz. (0.473L)
- #88861431 GM Vehicle Care Odor Eliminator 24 fl. oz. (0.710L)
In Canada:
- #10953203 GM Vehicle Care Wash & Wax Concentrate 473 mL
- #992727 GM Glass Cleaner Aerosol 500 g
- #10952905 GM Vehicle Care Liquid Cleaner/Wax 473 mL
- #10953013 GM Vehicle Care Chrome Cleaner and Polish 454 mL
- #10953202 GM Vehicle Care Wheel Brite 473 mL
- #88901678 GM Vehicle Care Odor Eliminator 473 mL
- Display signboards with the installed price for popular GM Accessories such as running boards
and Tonneau Covers. Customers may not think to ask about these desirable items at the time of a
service visit.
- Finally, take advantage of the GM Goodwrench initiatives (Tire Program, Goodwrench Credit
Card, etc. / Dealer Marketing Association (DMA) Promotions in Canada) to provide the customer
with more reasons to identify your dealership as the best place to go for parts and service.
Remember to utilize ALL of the service aspects you possess in your dealership to satisfy and
provide value to your customer. Many businesses exist profitably as an oil change location, a
vehicle repair facility, or a detailing shop alone. You already have the capabilities of all three and
provide these services with the inherent trust of your customer, under the GM Mark of Excellence.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Continuously Variable Transmission/Transaxle, CVT >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Continuously Variable
Transmission/Transaxle: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON
Continuously Variable Transmission/Transaxle: All Technical Service Bulletins Engine, A/T Shift/Driveability Concerns/MIL ON
Bulletin No.: 04-07-30-013B
Date: February 01, 2007
INFORMATION
Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon
(SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air
Filter
Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007
HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin
Number 04-07-30-013A (Section 07 - Transmission/Transaxle).
The use of an excessively/over-oiled aftermarket, reusable air filter may result in:
Service Engine Soon (SES) light on
Transmission shift concerns, slipping and damaged clutch(es) or band(s)
Engine driveability concerns, poor acceleration from a stop, limited engine RPM range
The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF)
sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from
the MAF may be low and any or all of the concerns listed above may occur.
When servicing a vehicle with any of these concerns, be sure to check for the presence of an
aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared
to a like vehicle with an OEM air box and filter under the same driving conditions to verify the
concern.
The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty.
If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and
the air induction hose for contamination of oil prior to making warranty repairs.
Transmission or engine driveability concerns (related to the MAF sensor being contaminated with
oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not
considered to be warrantable repair items.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Continuously Variable Transmission/Transaxle, CVT >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Continuously Variable
Transmission/Transaxle: > 04-07-30-013B > Feb > 07 > Engine, A/T - Shift/Driveability Concerns/MIL ON > Page 6447
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Continuously Variable Transmission/Transaxle, CVT >
Component Information > Technical Service Bulletins > All Other Service Bulletins for Continuously Variable
Transmission/Transaxle: > 04-06-01-029E > Apr > 10 > Vehicle - Engine Crankcase and Subsystems Flushing Info.
Continuously Variable Transmission/Transaxle: All Technical Service Bulletins Vehicle - Engine
Crankcase and Subsystems Flushing Info.
INFORMATION
Bulletin No.: 04-06-01-029E
Date: April 29, 2010
Subject: Unnecessary Flushing Services, Additive Recommendations and Proper Utilization of GM
Simplified Maintenance Schedule to Enhance Customer Service Experience
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to update the model years and add information about the
proper transmission flush procedure. Please discard Corporate Bulletin Number 04-06-01-029D
(Section 06 - Engine/Propulsion System).
An Overview of Proper Vehicle Service
General Motors is aware that some companies are marketing tools and equipment to support a
subsystem flushing procedures. These dedicated machines are in addition to many engine oil,
cooling system, fuel system, A/C, transmission flush and steering system additives available to the
consumer. GM Vehicles under normal usage do not require any additional procedures or additives
beyond what is advised under the former Vehicle Maintenance Schedules or the current Simplified
Maintenance Schedules. Do not confuse machines available from Kent-Moore/SPX that are
designed to aid and accelerate the process of fluid changing with these flushing machines.
Engine Crankcase Flushing
General Motors Corporation does not endorse or recommend engine crankcase flushing for any of
its gasoline engines. Analysis of some of the aftermarket materials used for crankcase flushing
indicate incompatibility with GM engine components and the potential for damage to some engine
seals and bearings. Damage to engine components resulting from crankcase flushing IS NOT
COVERED under the terms of the New Vehicle Warranty.
GM Authorized Service Information: Detailed, Descriptive, and Complete
If a specific model vehicle or powertrain need is identified, GM will issue an Authorized Service
Document containing a procedure and, if required, provide, make available, or require the specific
use of a machine, tool or chemical to accomplish proper vehicle servicing. An example of this is
fuel injector cleaning. Due to variation in fuel quality in different areas of the country, GM has
recognized the need for fuel injector cleaning methods on some engines, though under normal
circumstances, this service is not part of the maintenance requirements.
GM has published several gasoline fuel injector cleaning bulletins that fully outline the methods to
be used in conjunction with GM Part Numbered solutions to accomplish proper and safe cleaning
of the fuel injectors with preventative maintenance suggestions to maintain optimum performance.
You may refer to Corporate Bulletin Numbers 03-06-04-030 and 04-06-04-051 for additional
information on this subject.
Subsystem Flushing
Flushing of A/C lines, radiators, transmission coolers, and power steering systems are recognized
practices to be performed after catastrophic failures or extreme corrosion when encountered in
radiators. For acceptable A/C flushing concerns, refer to Corporate Bulletin Number 01-01-38-006.
This practice is NOT required or recommended for normal service operations.
The use of external transmission fluid exchange or flush machines is NOT recommended for the
automatic or manual transmission. Use of external machines to replace the fluid may affect the
operation or durability of the transmission. Transmission fluid should only be replaced by draining
and refilling following directions in SI. Refer to Automatic/Manual Transmission Fluid and Filter
Replacement.
Approved Transmission Flushing Tool (Transmission Cooler Only)
The Automatic Transmission Oil Cooler Flush and Flow Test Tool is recommended for GM
vehicles. Refer to Transmission Fluid Cooler Flushing and Flow Test in SI using the J 45096.
Service Is Important to You and Your Customer
General Motors takes great pride in offering our dealerships and customers high quality vehicles
that require extremely low maintenance over the life of the vehicle. This low cost of ownership
builds repeat sales and offers our customers measurable economy of operation against competing
vehicles.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Continuously Variable Transmission/Transaxle, CVT >
Component Information > Technical Service Bulletins > All Other Service Bulletins for Continuously Variable
Transmission/Transaxle: > 04-06-01-029E > Apr > 10 > Vehicle - Engine Crankcase and Subsystems Flushing Info. > Page
6453
Providing responsible services at the proper intervals will greatly aid your dealership with repeat
business, and additional services when required. Most customers appreciate and gain trust in the
dealership that informs and offers them just what they need for continued trouble-free operation.
Examine your service department's practices and verify that all Service Consultants and
Technicians focus on customer satisfaction, vehicle inspections, and other products at time of
service. Use this opportunity to upgrade the services you provide to your customers. Here are a
few suggestions:
- Take the time required to align your dealership service practices with the new GM Simplified
Maintenance Schedule. Use the new vehicle Owner's Manual Maintenance I and II schedules to
create a "mirror image" in your advertising and dealer service pricing that is easily understandable
to your customer. Taking advantage of this new service strategy may greatly increase your
dealership service sales and customer retention while decreasing the frequency of visits and
inconvenience to your customer.
- Review your program to ensure that all vehicles coming in are evaluated for safety and wear
items. Examine all vehicles for tire condition, signs of misalignment, brake wear, exterior lamp
functionality, exhaust condition, A/C cooling performance, SRS or Air Bag MIL, along with Service
Engine Soon or Check Engine indicators. If the Service Engine Soon or Check Engine MIL is
illuminated, it is vital that you inform the customer of the concerns with ignoring the indicator and
what the required repair would cost. In addition to the possibility of increased emissions and
driveability concerns, many customers are unaware that lower gas mileage may also result, with
additional cost to the customer.
- Be complete in your service recommendations. Some sales opportunities are not being fully
pursued nationally. Focus on overlooked but required maintenance that has real benefits to the
customer. Many vehicles are equipped with cabin air filters. If these filters are used beyond
replacement time, they may impede airflow decreasing A/C and heating performance. Make sure
these filters are part of your recommended service. Note that some of our vehicles may not have
been factory equipped but will accept the filters as an accessory.
- Express the value in maintaining the finish quality of the customer's vehicle at the Maintenance I
and II visits. More fully utilize the vehicle prep personnel you already have in place. In today's
world, many people simply ignore the finish of their vehicle, at best infrequently using an automatic
car wash for exterior cleaning. Offer vehicle detailing services in stages from just a wash and wax
to a complete interior cleaning. When paired with the Simplified Maintenance visit, this will increase
customer satisfaction. On return, the customer gets a visibly improved vehicle that will be a source
of pride of ownership along with a vehicle that is now fully maintained. Also, reinforce the improved
resale value of a completely maintained vehicle.
- For customers who clean and maintain the appearance of their vehicles themselves encourage
the use of GM Vehicle Care products. Many customers may have never used GM Car Wash/Wax
Concentrate, GM Cleaner Wax or a longtime product, GM Glass Cleaner, which is a favorite of
many customers who try it just once. If your dealership give samples of these products with new
car purchases, customers may already be sold on the product but not willing to make a special trip
to the dealership. Capitalize on sales at this time. Stock shelves right at the Service counter with
these products and consider instituting compensation programs for Service Consultants who
suggest these products. Many consumers faced with an intimidating wall full of car care products
sold at local auto parts stores may find it comforting to purchase a fully tested product sold by GM
that they know will not harm the finish of their vehicle. We suggest these competitively priced basic
vehicle care products to emphasize:
In USA:
- #12378401 GM Vehicle Care Wash/Wax Concentrate 16 fl. oz. (0.473L)
- #89021822 GM Vehicle Care Glass Cleaner Aerosol 18 oz. (510 g)
- #12377966 GM Vehicle Care Cleaner Wax 16 fl. oz. (0.473L)
- #1052929 GM Vehicle Care Chrome and Wire Wheel Cleaner 16 fl. oz. (0.473L)
- #88861431 GM Vehicle Care Odor Eliminator 24 fl. oz. (0.710L)
In Canada:
- #10953203 GM Vehicle Care Wash & Wax Concentrate 473 mL
- #992727 GM Glass Cleaner Aerosol 500 g
- #10952905 GM Vehicle Care Liquid Cleaner/Wax 473 mL
- #10953013 GM Vehicle Care Chrome Cleaner and Polish 454 mL
- #10953202 GM Vehicle Care Wheel Brite 473 mL
- #88901678 GM Vehicle Care Odor Eliminator 473 mL
- Display signboards with the installed price for popular GM Accessories such as running boards
and Tonneau Covers. Customers may not think to ask about these desirable items at the time of a
service visit.
- Finally, take advantage of the GM Goodwrench initiatives (Tire Program, Goodwrench Credit
Card, etc. / Dealer Marketing Association (DMA) Promotions in Canada) to provide the customer
with more reasons to identify your dealership as the best place to go for parts and service.
Remember to utilize ALL of the service aspects you possess in your dealership to satisfy and
provide value to your customer. Many businesses exist profitably as an oil change location, a
vehicle repair facility, or a detailing shop alone. You already have the capabilities of all three and
provide these services with the inherent trust of your customer, under the GM Mark of Excellence.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Carrier > Component
Information > Adjustments > Differential Side Bearing Preload
Differential Carrier: Adjustments Differential Side Bearing Preload
Fig. 11 Service Shim Thickness Chart.
DIFFERENTIAL SIDE BEARING PRELOAD ADJUSTMENTS
On these models, side bearing preload should be set before pinion is installed. If pinion is installed,
remove ring gear.
1. Ensure bearing bores in housing and bearing caps are clean and free from burrs. 2. Measure
production shims or service spacer and shim packs removed during disassembly to determine
approximate thickness of shims needed for
installation. Do not reuse cast iron production shims as they may break during installation. If
service spacers and shims were previously installed, they can be reused.
3. In addition to .170 inch service spacers for each side, refer to chart, Fig. 11, and select service
shim thickness required based on measurements
made in step 2.
4. Place outer races over side bearings, mount differential assembly in housing and insert service
spacer between each bearing race and housing with
chamfered edge against housing.
5. Install left bearing cap to retain case assembly and tighten bolts hand tight so that case can be
moved while checking adjustments. A bearing cap
bolt can be installed in lower right bearing cap hole to prevent case from dropping while performing
shim adjustments.
6. Select one or two shims totaling thickness calculated in step 3 and insert shims between right
bearing cap and service spacer. 7. Insert progressively larger feeler gauges between shim and
service spacer until noticeable increase in drag can be felt, pushing gauge down until it
contacts housing bore to obtain proper reading. Rotate case while inserting gauges to ensure even
readings.
8. The gauge used just before additional drag is felt is correct thickness to obtain "zero preload. By
starting with a thin gauge a sense of feel can be
obtained for the original light drag caused by the weight of the case, allowing the drag caused by
the beginning of preload to be recognized. It will be necessary to work case in and out and to the
left in order to insert feeler gauges.
9. When the proper gauge thickness has been determined to obtain zero preload, remove bearing
cap, case assembly service spacers and shim pack.
10. Select two service shims of approximate equal thickness whose total thickness is equal to the
thickness of the shims installed in step 6 plus the
thickness of the feeler gauge used to obtain zero preload.
11. Shims selected during this procedure allow differential assembly to be installed at zero preload,
the equivalent of a "slip-fit in case, during
backlash adjustment. Final preload is not added until backlash has been adjusted.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Carrier > Component
Information > Adjustments > Differential Side Bearing Preload > Page 6459
Differential Carrier: Adjustments Pinion Depth Adjustment
Fig. 12 Pinion Gauge Plate Installation.
Fig. 13 Pinion Depth Check.
PINION DEPTH ADJUSTMENT
1. Install pinion bearing races in housing using a suitable driver. 2. Lubricate pinion bearings and
install bearings in races. 3. Mount depth gauging jig in housing, Fig. 12, noting the following:
a. Assemble gauge plate onto preload stud. b. Hold pinion bearings in position, insert stud through
rear bearing and pilot and front bearing and pilot, then install retaining nut and tighten nut
until snug.
c. Rotate tool to ensure bearings are properly seated. d. Hold preload stud and tighten nut until 20
inch lbs. of torque is required to rotate stud. To prevent damage to bearing, tighten nut in small
increments, checking rotating torque after each adjustment.
e. Mount side bearing discs on arbor, using step for disc that corresponds to base of housing. f.
Mount arbor and plunger assembly in housing, ensuring side bearing discs are properly seated,
install bearing caps and tighten cap bolts to prevent bearing discs from moving, Fig. 13.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Carrier > Component
Information > Adjustments > Differential Side Bearing Preload > Page 6460
4. Mount dial indicator on arbor stud with indicator contact button bearing against top of arbor
plunger. 5. Preload indicator 3/4 revolution and secure to arbor mounting stud in this position. 6.
Place arbor plunger on gauge plate, rotating plate as needed so that plunger rests directly on
button corresponding to ring gear size. 7. Slowly rock plunger rod back and forth across button
while observing dial indicator. 8. At point on button where indicator registers greatest deflection,
zero dial indicator. Perform above two steps several times to ensure correct
setting.
9. Once verified zero reading is obtained, swing plunger aside until it is clear of gauge plate button
and record dial indicator reading. Indicator will
now read required pinion depth shim thickness for a nominal pinion.
10. Inspect rear face of drive pinion to be installed for a pinion code number. This number indicates
in thousandths of an inch necessary modification
of pinion shim thickness obtained in step 9.
11. Select pinion depth adjusting shim as follows:
a. If pinion is stamped with a plus (+) number, add that number of thousandths to dimension
obtained in step 9. b. If pinion is stamped with a minus (−) number, subtract that many thousandths
from dimension obtained in step 9. c. If pinion is not stamped with plus or minus number, dimension
obtained in step 9 is correct shim thickness.
12. Remove gauging tools and pinion bearings from housing, noting installation position of
bearings.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Locations
LH Rear Frame Rail (Without Automatic Level Control)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble
Differential Axle Housing: Service and Repair Disassemble and Disassemble
Fig. 3 Exploded View Of Rear Axle Assembly (Part 1 Of 2).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble > Page 6466
Fig. 3 Exploded View Of Rear Axle Assembly (Part 2 Of 2).
DISASSEMBLE
1. Raise and support rear of vehicle, then loosen axle housing cover bolts and allow lubricant to
drain into suitable container, Fig. 3 . 2. Remove axle housing cover, then proceed as follows:
a. Wipe excess lubricant from inside axle housing, then visually inspect parts for wear and/or
damage. b. Rotate gears and check for roughness, indicating damaged bearings or gears. c. Install
dial indicator on axle housing cover flange, then check and record ring gear to drive pinion
backlash.
3. Remove rear axles and propeller shaft. Refer to appropriate chassis chapter for procedures. 4. If
not previously marked, scribe reference marks on differential bearing caps to be used during
reassembly, then loosen bearing cap bolts. 5. Using suitable tool, pry differential case, bearing
races and shims out of housing until loose in the bearing caps. Remove bearing races, then the
differential assembly. Mark side cups and shims for reference during reassembly.
Fig. 15 Ring Gear & Pinion Backlash Check.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble > Page 6467
Fig. 7 Front Hub & Wheel Bearing Assembly.
ASSEMBLE
1. Ensure pinion depth and bearing preload are properly adjusted, as described under
Adjustments. See: Pinion Gear/Adjustments 2. Install differential case assembly and selected side
bearing shims as described under Adjustments. See: Pinion Gear/Adjustments 3. Install bearing
caps in proper position and torque cap bolts to 55 ft. lbs. 4. Rotate assembly to ensure bearings
are properly seated. 5. Mount dial indicator on housing with plunger bearing against tooth on ring
gear, Fig. 15. Use small contact button on indicator plunger so that
contact can be made at heel end of tooth and position dial indicator with plunger inline with gear
rotation and perpendicular to gear tooth.
6. Hold pinion stationary and rock ring gear back and forth while reading backlash on indicator. 7.
Check backlash at three evenly spaced positions around ring gear and record readings. If backlash
varies by more than 0.002 inch at any
position, check ring gear installation and runout, and correct as needed.
8. If backlash is not within specifications, remove differential case assembly and bearing shims
keeping shims in order. 9. Backlash is adjusted by increasing thickness of one shim while
decreasing thickness of opposite side shim by the same amount in order to maintain
proper side bearing preload. Select shims to adjust backlash as follows: a. If backlash is excessive,
increase thickness of shim on gear tooth side and decrease thickness of shim on opposite side by
the same amount. b. If backlash is less than specified, decrease thickness of shim on gear tooth
side while increasing thickness of opposite shim by the same
amount. Each 0.002 inch change in shim thickness alters backlash by 0.001 inch.
10. Reinstall differential assembly, shims and bearing caps, torque bearing cap bolts to 55 ft. lbs.,
then recheck backlash and adjust as needed. 11. If side bearing preload was set to zero during
side bearing preload adjustment, proceed as follows:
a. Remove both bearing caps and shim packs, keeping shim packs in respective left or right
positions. b. Select left side differential preload shim from specifications chart and insert shim
between left bearing race and spacer, then install left bearing
cap with bolts hand tight.
c. Select right side differential preload shim from specifications chart and insert shim between right
bearing race and spacer using a soft faced
hammer.
d. Install right bearing cap and torque all cap bolts to 55 ft. lbs.
12. Ensure ring gear teeth are clean and free from oil, then coat both drive and coast side of each
tooth with marking compound. 13. Apply braking force to load ring gear, then rotate driveshaft yoke
with wrench so that ring gear rotates one full revolution in each direction. Test
made without loading gears will not yield satisfactory pattern, excessive rotating of gears is not
recommended.
14. Compare gear tooth pattern with Fig. 16, and correct assembly adjustments as needed. 15.
When proper gear tooth contact pattern has been obtained, clean marking compound from gears.
16. Install axles and driveshaft. Refer to Drive/Propeller Shafts, Bearings and Joints for procedures.
See: Drive/Propeller Shafts, Bearings and
Joints/Drive/Propeller Shaft/Service and Repair
17. Install rear cover using RTV or new gasket and torque cover bolts to 20 ft. lbs., then fill rear
axle with appropriate lubricant. 18. On models equipped with limited slip differential, add additive
No. 1050428 or equivalent to rear axle lubricant.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble > Page 6468
Differential Axle Housing: Service and Repair Cleaning & Inspection
CLEANING AND INSPECTION
1. Clean components in solvent and blow dry with compressed air, noting the following:
a. Do not use brush when cleaning bearings. b. Do not spin dry bearings, as bearings will be
damaged. c. Lightly lubricate components after cleaning to retard corrosion. d. Keep all
components in order to ensure proper assembly.
2. Inspect gears for cracks, chipped teeth, wear and scoring, and damaged bearing or mounting
surfaces. Replace gears that are damaged or
excessively worn.
NOTE: Ring gear and pinion must be replaced as an assembly.
3. Inspect differential case for cracks, damage, worn side gear bores and scored bearing surfaces
and replace as needed. 4. Inspect housing for scored bearing mount surfaces, cracks and
distortion, and replace as needed. 5. Inspect bearing rollers and races for pitting, scoring,
overheating and damage. 6. Mate bearing with race and check operation. 7. Replace any bearing
that is damaged, excessively worn or that fails to operate smoothly. 8. Mount differential case along
with side bearings and ring gear in housing, and check runout with side bearings adjusted for zero
preload and a dial
indicator positioned against machined edge of ring gear.
9. If runout exceeds 0.003 inch, and gear cannot be positioned to eliminate runout, ring gear and/or
case should be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble > Page 6469
Differential Axle Housing: Service and Repair Overhaul
Standard Differential
Fig. 3 Exploded View Of Rear Axle Assembly (Part 1 Of 2).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble > Page 6470
Fig. 3 Exploded View Of Rear Axle Assembly (Part 2 Of 2).
1. If side carrier bearings are to be replaced, remove bearings using a bearing puller. 2. Remove
differential pinion shaft lock bolt and the pinion shaft, Fig. 3 . 3. Remove differential pinions and
thrust washers, side gears and side gear thrust washers, noting installation position for assembly.
Keep thrust
washers with respective gears.
4. Remove ring gear bolts, then the ring gear, driving ring gear from case using drift and hammer.
Ring gear bolts have left hand threads. Do not pry
between ring gear and case, as mating surfaces will be damaged.
5. Inspect components as outlined in Cleaning & Inspection and replace as needed. See: Cleaning
& Inspection 6. Install thrust washers on side gears and mount side gears in case. Lubricate all
components with specified gear lubricant prior to assembly. 7. Position one differential pinion (less
thrust washer) between side gears and rotate gears until pinion is directly opposite case loading
opening. 8. Install other pinion with pinion shaft holes aligned, then rotate side gears and ensure
pinions align with shaft openings in case. 9. When pinions are properly aligned, rotate pinions
toward loading opening just enough to allow thrust washer installation and install washers.
10. Align pinions with shaft opening in case, insert pinion shaft through case, install new lock bolt. It
is not necessary to torque lock bolt at this time. 11. Ensure ring gear and case mating surfaces are
clean and free from burrs, mount gear on case, install two new retaining bolts at opposite sides of
gear and alternately tighten bolts to draw gear on case.
12. Install remaining ring gear bolts hand tight and ensure gear is squarely seated on case. Always
use new bolts of proper type when installing ring
gear. Do not reuse old bolts.
13. Alternately torque ring gear bolts to 89 ft. lbs. 14. Press side bearings onto case. If old bearings
are reused, ensure bearings are installed in their original position.
Limited Slip
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Differential Axle Housing >
Component Information > Service and Repair > Disassemble and Disassemble > Page 6471
Fig. 7 Cutaway View Of Auburn Type Limited Slip Differential.
These models use an Auburn Type limited slip differential Fig. 7 which can not be serviced.
1. Remove case side bearings using tool No. J-22888 or equivalent. 2. Remove all but two
opposite ring gear attaching bolts, then loosen the two remaining bolts. 3. Loosen ring gear by
tapping on bolts, then remove ring gear from differential. 4. This limited slip rear axle case is not
serviceable. If differential case is not satisfactory, replace complete assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Fluid - Differential > Component
Information > Technical Service Bulletins > Drivetrain - Recommended Axle Lubricant
Fluid - Differential: Technical Service Bulletins Drivetrain - Recommended Axle Lubricant
File In Section: 0 - General Information
Bulletin No.: 76-02-02A
Date: October, 1998
INFORMATION
Subject: Recommended Axle Lubricant
Models: 1999 and Prior Rear Wheel Drive Passenger Cars, Light and Medium Duty Trucks, and
Four Wheel Drive Vehicles
This bulletin is being revised to add the 1998 and 1999 Model Years and add Vehicle Line and
Recommended Axle Lubricant Information. Please discard Corporate Bulletin Number 76-02-02
(Section 0 - General Information).
The following tables provide the latest information on recommended axle lubricant.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Fluid - Differential > Component
Information > Technical Service Bulletins > Drivetrain - Recommended Axle Lubricant > Page 6476
Parts Information
Parts are currently available from GMSPO.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Fluid - Differential > Component
Information > Technical Service Bulletins > Page 6477
Fluid - Differential: Specifications
Fluid Type
Standard Differential ^ SAE 80W-90 GL-5 gear lubricant Limited Slip Differential ^ Lubricant
additive (GM P/N 1052358) and ^ SAE 80W-90 GL-5 gear lubricant
Capacity
Drain and Refill ....................................................................................................................................
................................................. 1.7 liters (3.5 pt) Additive ...................................................................
.................................................................................................................... 118 milliliters (4 fl oz)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Bearing, Differential >
Component Information > Adjustments > Differential Side Bearing Preload
Pinion Bearing: Adjustments Differential Side Bearing Preload
Fig. 11 Service Shim Thickness Chart.
DIFFERENTIAL SIDE BEARING PRELOAD ADJUSTMENTS
On these models, side bearing preload should be set before pinion is installed. If pinion is installed,
remove ring gear.
1. Ensure bearing bores in housing and bearing caps are clean and free from burrs. 2. Measure
production shims or service spacer and shim packs removed during disassembly to determine
approximate thickness of shims needed for
installation. Do not reuse cast iron production shims as they may break during installation. If
service spacers and shims were previously installed, they can be reused.
3. In addition to .170 inch service spacers for each side, refer to chart, Fig. 11, and select service
shim thickness required based on measurements
made in step 2.
4. Place outer races over side bearings, mount differential assembly in housing and insert service
spacer between each bearing race and housing with
chamfered edge against housing.
5. Install left bearing cap to retain case assembly and tighten bolts hand tight so that case can be
moved while checking adjustments. A bearing cap
bolt can be installed in lower right bearing cap hole to prevent case from dropping while performing
shim adjustments.
6. Select one or two shims totaling thickness calculated in step 3 and insert shims between right
bearing cap and service spacer. 7. Insert progressively larger feeler gauges between shim and
service spacer until noticeable increase in drag can be felt, pushing gauge down until it
contacts housing bore to obtain proper reading. Rotate case while inserting gauges to ensure even
readings.
8. The gauge used just before additional drag is felt is correct thickness to obtain "zero preload. By
starting with a thin gauge a sense of feel can be
obtained for the original light drag caused by the weight of the case, allowing the drag caused by
the beginning of preload to be recognized. It will be necessary to work case in and out and to the
left in order to insert feeler gauges.
9. When the proper gauge thickness has been determined to obtain zero preload, remove bearing
cap, case assembly service spacers and shim pack.
10. Select two service shims of approximate equal thickness whose total thickness is equal to the
thickness of the shims installed in step 6 plus the
thickness of the feeler gauge used to obtain zero preload.
11. Shims selected during this procedure allow differential assembly to be installed at zero preload,
the equivalent of a "slip-fit in case, during
backlash adjustment. Final preload is not added until backlash has been adjusted.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Bearing, Differential >
Component Information > Adjustments > Differential Side Bearing Preload > Page 6482
Pinion Bearing: Adjustments Pinion Depth Adjustment
Fig. 12 Pinion Gauge Plate Installation.
Fig. 13 Pinion Depth Check.
PINION DEPTH ADJUSTMENT
1. Install pinion bearing races in housing using a suitable driver. 2. Lubricate pinion bearings and
install bearings in races. 3. Mount depth gauging jig in housing, Fig. 12, noting the following:
a. Assemble gauge plate onto preload stud. b. Hold pinion bearings in position, insert stud through
rear bearing and pilot and front bearing and pilot, then install retaining nut and tighten nut
until snug.
c. Rotate tool to ensure bearings are properly seated. d. Hold preload stud and tighten nut until 20
inch lbs. of torque is required to rotate stud. To prevent damage to bearing, tighten nut in small
increments, checking rotating torque after each adjustment.
e. Mount side bearing discs on arbor, using step for disc that corresponds to base of housing. f.
Mount arbor and plunger assembly in housing, ensuring side bearing discs are properly seated,
install bearing caps and tighten cap bolts to prevent bearing discs from moving, Fig. 13.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Bearing, Differential >
Component Information > Adjustments > Differential Side Bearing Preload > Page 6483
4. Mount dial indicator on arbor stud with indicator contact button bearing against top of arbor
plunger. 5. Preload indicator 3/4 revolution and secure to arbor mounting stud in this position. 6.
Place arbor plunger on gauge plate, rotating plate as needed so that plunger rests directly on
button corresponding to ring gear size. 7. Slowly rock plunger rod back and forth across button
while observing dial indicator. 8. At point on button where indicator registers greatest deflection,
zero dial indicator. Perform above two steps several times to ensure correct
setting.
9. Once verified zero reading is obtained, swing plunger aside until it is clear of gauge plate button
and record dial indicator reading. Indicator will
now read required pinion depth shim thickness for a nominal pinion.
10. Inspect rear face of drive pinion to be installed for a pinion code number. This number indicates
in thousandths of an inch necessary modification
of pinion shim thickness obtained in step 9.
11. Select pinion depth adjusting shim as follows:
a. If pinion is stamped with a plus (+) number, add that number of thousandths to dimension
obtained in step 9. b. If pinion is stamped with a minus (−) number, subtract that many thousandths
from dimension obtained in step 9. c. If pinion is not stamped with plus or minus number, dimension
obtained in step 9 is correct shim thickness.
12. Remove gauging tools and pinion bearings from housing, noting installation position of
bearings.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Gear, Differential >
Component Information > Adjustments > Differential Side Bearing Preload
Pinion Gear: Adjustments Differential Side Bearing Preload
Fig. 11 Service Shim Thickness Chart.
DIFFERENTIAL SIDE BEARING PRELOAD ADJUSTMENTS
On these models, side bearing preload should be set before pinion is installed. If pinion is installed,
remove ring gear.
1. Ensure bearing bores in housing and bearing caps are clean and free from burrs. 2. Measure
production shims or service spacer and shim packs removed during disassembly to determine
approximate thickness of shims needed for
installation. Do not reuse cast iron production shims as they may break during installation. If
service spacers and shims were previously installed, they can be reused.
3. In addition to .170 inch service spacers for each side, refer to chart, Fig. 11, and select service
shim thickness required based on measurements
made in step 2.
4. Place outer races over side bearings, mount differential assembly in housing and insert service
spacer between each bearing race and housing with
chamfered edge against housing.
5. Install left bearing cap to retain case assembly and tighten bolts hand tight so that case can be
moved while checking adjustments. A bearing cap
bolt can be installed in lower right bearing cap hole to prevent case from dropping while performing
shim adjustments.
6. Select one or two shims totaling thickness calculated in step 3 and insert shims between right
bearing cap and service spacer. 7. Insert progressively larger feeler gauges between shim and
service spacer until noticeable increase in drag can be felt, pushing gauge down until it
contacts housing bore to obtain proper reading. Rotate case while inserting gauges to ensure even
readings.
8. The gauge used just before additional drag is felt is correct thickness to obtain "zero preload. By
starting with a thin gauge a sense of feel can be
obtained for the original light drag caused by the weight of the case, allowing the drag caused by
the beginning of preload to be recognized. It will be necessary to work case in and out and to the
left in order to insert feeler gauges.
9. When the proper gauge thickness has been determined to obtain zero preload, remove bearing
cap, case assembly service spacers and shim pack.
10. Select two service shims of approximate equal thickness whose total thickness is equal to the
thickness of the shims installed in step 6 plus the
thickness of the feeler gauge used to obtain zero preload.
11. Shims selected during this procedure allow differential assembly to be installed at zero preload,
the equivalent of a "slip-fit in case, during
backlash adjustment. Final preload is not added until backlash has been adjusted.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Gear, Differential >
Component Information > Adjustments > Differential Side Bearing Preload > Page 6488
Pinion Gear: Adjustments Pinion Depth Adjustment
Fig. 12 Pinion Gauge Plate Installation.
Fig. 13 Pinion Depth Check.
PINION DEPTH ADJUSTMENT
1. Install pinion bearing races in housing using a suitable driver. 2. Lubricate pinion bearings and
install bearings in races. 3. Mount depth gauging jig in housing, Fig. 12, noting the following:
a. Assemble gauge plate onto preload stud. b. Hold pinion bearings in position, insert stud through
rear bearing and pilot and front bearing and pilot, then install retaining nut and tighten nut
until snug.
c. Rotate tool to ensure bearings are properly seated. d. Hold preload stud and tighten nut until 20
inch lbs. of torque is required to rotate stud. To prevent damage to bearing, tighten nut in small
increments, checking rotating torque after each adjustment.
e. Mount side bearing discs on arbor, using step for disc that corresponds to base of housing. f.
Mount arbor and plunger assembly in housing, ensuring side bearing discs are properly seated,
install bearing caps and tighten cap bolts to prevent bearing discs from moving, Fig. 13.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Gear, Differential >
Component Information > Adjustments > Differential Side Bearing Preload > Page 6489
4. Mount dial indicator on arbor stud with indicator contact button bearing against top of arbor
plunger. 5. Preload indicator 3/4 revolution and secure to arbor mounting stud in this position. 6.
Place arbor plunger on gauge plate, rotating plate as needed so that plunger rests directly on
button corresponding to ring gear size. 7. Slowly rock plunger rod back and forth across button
while observing dial indicator. 8. At point on button where indicator registers greatest deflection,
zero dial indicator. Perform above two steps several times to ensure correct
setting.
9. Once verified zero reading is obtained, swing plunger aside until it is clear of gauge plate button
and record dial indicator reading. Indicator will
now read required pinion depth shim thickness for a nominal pinion.
10. Inspect rear face of drive pinion to be installed for a pinion code number. This number indicates
in thousandths of an inch necessary modification
of pinion shim thickness obtained in step 9.
11. Select pinion depth adjusting shim as follows:
a. If pinion is stamped with a plus (+) number, add that number of thousandths to dimension
obtained in step 9. b. If pinion is stamped with a minus (−) number, subtract that many thousandths
from dimension obtained in step 9. c. If pinion is not stamped with plus or minus number, dimension
obtained in step 9 is correct shim thickness.
12. Remove gauging tools and pinion bearings from housing, noting installation position of
bearings.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Gear, Differential >
Component Information > Service and Repair > Removal and Installation
Pinion Gear: Service and Repair Removal and Installation
REMOVAL
1. Scribe reference mark between drive pinion and driveshaft yoke, then hold yoke with suitable
tool and remove pinion nut and yoke. If yoke shows
wear in the seal-to-flange contacting surface, the yoke should be replaced.
2. Install original pinion nut a few turns on pinion shaft, then using hammer and drift, tap pinion
shaft out of pinion housing. Hold gear end of
pinion shaft when removing to prevent it from falling from axle housing.
3. Remove and discard pinion nut and collapsible spacer. 4. If being replaced, remove front and
rear bearing races from pinion housing using drift positioned in race slots and hammer. 5. If rear
pinion bearing is being replaced, remove using arbor press and adapters. Measure and record
thickness of shim which is found under rear
bearing.
INSTALLATION
1. Install selected shim onto pinion shaft, lubricate rear pinion bearing with specified axle lubricant,
then press rear bearing onto pinion using suitable
spacers.
2. Install new collapsible spacer onto pinion shaft, then insert pinion assembly into housing. 3.
Lubricate front pinion bearing, install bearing into housing and tap bearing over pinion shaft with a
drift while assistant holds pinion in place. Old
pinion nut and a large washer can be used to seat front bearing on pinion, but care must be taken
not to collapse spacer if this method is used.
4. Install new pinion seal in housing, coat seal lips with grease, then mount driveshaft yoke on
pinion shaft, lightly tapping yoke until several pinion
shaft threads protrude from yoke.
5. Coat rear of pinion washer with suitable sealer, then install washer and new pinion nut. 6. Hold
driveshaft yoke with suitable tool, then alternately tighten pinion nut and rotate pinion until endplay
is reduced to zero. 7. When endplay is reduced to zero, check pinion bearing preload using a
torque wrench. 8. Continue tightening pinion nut in small increments until 35-40 inch lbs. of bearing
preload is obtained with new bearings or 20-25 inch lbs. of
bearing preload is obtained with used bearings, rotating pinion and checking preload after each
adjustment.
NOTE: Exceeding preload specification will compress collapsible spacer too far, requiring
replacement of spacer. If preload specification is exceeded, spacer must be replaced and
adjustment procedure must be repeated. Do not loosen pinion nut to reduce preload.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Gear, Differential >
Component Information > Service and Repair > Removal and Installation > Page 6492
Pinion Gear: Service and Repair Assemble and Preload
Fig. 15 Ring Gear & Pinion Backlash Check.
Fig. 7 Front Hub & Wheel Bearing Assembly.
ASSEMBLE
1. Ensure pinion depth and bearing preload are properly adjusted, as described under
Adjustments. See: Adjustments 2. Install differential case assembly and selected side bearing
shims as described under Adjustments. See: Adjustments 3. Install bearing caps in proper position
and torque cap bolts to 55 ft. lbs. 4. Rotate assembly to ensure bearings are properly seated. 5.
Mount dial indicator on housing with plunger bearing against tooth on ring gear, Fig. 15. Use small
contact button on indicator plunger so that
contact can be made at heel end of tooth and position dial indicator with plunger inline with gear
rotation and perpendicular to gear tooth.
6. Hold pinion stationary and rock ring gear back and forth while reading backlash on indicator. 7.
Check backlash at three evenly spaced positions around ring gear and record readings. If backlash
varies by more than 0.002 inch at any
position, check ring gear installation and runout, and correct as needed.
8. If backlash is not within specifications, remove differential case assembly and bearing shims
keeping shims in order. 9. Backlash is adjusted by increasing thickness of one shim while
decreasing thickness of opposite side shim by the same amount in order to maintain
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Differential Assembly > Pinion Gear, Differential >
Component Information > Service and Repair > Removal and Installation > Page 6493
proper side bearing preload. Select shims to adjust backlash as follows: a. If backlash is excessive,
increase thickness of shim on gear tooth side and decrease thickness of shim on opposite side by
the same amount. b. If backlash is less than specified, decrease thickness of shim on gear tooth
side while increasing thickness of opposite shim by the same
amount. Each 0.002 inch change in shim thickness alters backlash by 0.001 inch.
10. Reinstall differential assembly, shims and bearing caps, torque bearing cap bolts to 55 ft. lbs.,
then recheck backlash and adjust as needed. 11. If side bearing preload was set to zero during
side bearing preload adjustment, proceed as follows:
a. Remove both bearing caps and shim packs, keeping shim packs in respective left or right
positions. b. Select left side differential preload shim from specifications chart and insert shim
between left bearing race and spacer, then install left bearing
cap with bolts hand tight.
c. Select right side differential preload shim from specifications chart and insert shim between right
bearing race and spacer using a soft faced
hammer.
d. Install right bearing cap and torque all cap bolts to 55 ft. lbs.
12. Ensure ring gear teeth are clean and free from oil, then coat both drive and coast side of each
tooth with marking compound. 13. Apply braking force to load ring gear, then rotate driveshaft yoke
with wrench so that ring gear rotates one full revolution in each direction. Test
made without loading gears will not yield satisfactory pattern, excessive rotating of gears is not
recommended.
14. Compare gear tooth pattern with Fig. 16, and correct assembly adjustments as needed. 15.
When proper gear tooth contact pattern has been obtained, clean marking compound from gears.
16. Install axles and driveshaft. Refer to Drive/Propeller Shafts, Bearings and Joints for procedures.
See: Drive/Propeller Shafts, Bearings and
Joints/Drive/Propeller Shaft/Service and Repair
17. Install rear cover using RTV or new gasket and torque cover bolts to 20 ft. lbs., then fill rear
axle with appropriate lubricant. 18. On models equipped with limited slip differential, add additive
No. 1050428 or equivalent to rear axle lubricant.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive Axles, Bearings and Joints > Axle Shaft Assembly >
Component Information > Service and Repair
Axle Shaft Assembly: Service and Repair
REAR AXLE SHAFT
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive Axles, Bearings and Joints > Axle Shaft Assembly >
Component Information > Service and Repair > Page 6498
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive Axles, Bearings and Joints > Axle Shaft Assembly >
Component Information > Service and Repair > Page 6499
Remove
1. Raise and suitably support vehicle. 2. Rear tire and wheels. 3. Rear brake drums, on vehicles
equipped with rear drum brake systems. 4. Rotor and rear parking brake shoe lining, on vehicles
equipped with rear disc brake systems. 5. Housing cover. 6. Bolt/screw (5) from case (7). 7. Pinion
gear shaft (6) from case (7). 8. Shaft lock (38).
^ Access by pushing the flanged end of the shaft (39) into housing (37).
9. Axle shaft (39) from housing (37), being careful not to damage seal (34) or sensor (49) and
sensor ring.
^ Hold a shop towel under axle shaft (39) to prevent axle lubricant from contaminating brake shoes
and linings.
Install
1. Shaft (39) into place taking care that splines on the end of shaft (39) do not damage seal (34)
and that they engage with the splines of the side gear
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive Axles, Bearings and Joints > Axle Shaft Assembly >
Component Information > Service and Repair > Page 6500
(10).
^ The 30-spline, 8 1/2-inch ring gear rear axle shaft is not interchangeable with any pre-1989 shaft.
2. Shaft lock (38).
^ Push axle shaft (39) outward so that shaft lock (38) seats in counterbore of side gear (10).
3. Pinion gear shaft (6) through case (7), thrust washers (11) and pinion gears (12), align the hole
in shaft (6) with the shaft lock bolt/screw hole. 4. Bolt/screw (5).
^ Coat threads with Locktite 242 (GM P/N 12345382) or equivalent.
Tighten Tighten bolt/screw (5) to 36 Nm (27 lb. ft.).
5 Housing cover.
6. rear brake drum. 7
Rotor and rear parking brake shoe and linings, if removed.
8 Rear tire and wheels.
9 Lower vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive Axles, Bearings and Joints > Wheel Bearing >
Component Information > Adjustments
Wheel Bearing: Adjustments
FRONT WHEEL BEARINGS ADJUSTMENT
Fig. 2 Front Wheel Bearing Adjustment
1. While rotating wheel forward, torque spindle nut to 12 ft. lbs., Fig. 2. 2. Back off nut until just
loose then hand tighten nut and back it off again until either hole in spindle lines up with hole in nut.
Do not back off nut
more than 1/2 flat.
3. Install new cotter pin. With wheel bearing properly adjusted, there will be .001-.005 inch end
play.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive Axles, Bearings and Joints > Wheel Bearing >
Component Information > Adjustments > Page 6504
Wheel Bearing: Service and Repair
FRONT WHEEL BEARINGS
Fig. 3 Hub & Wheel Bearing Replacement
1. Raise car and remove front wheels. 2. On models equipped with anti-lock brake systems,
remove right and left wheel speed sensors as follows:
a. Under vehicle hood, disconnect speed sensor electrical harness. b. Raise and support vehicle,
then remove speed sensor harness bracket attaching bolt. c. Remove speed sensor to steering
knuckle attaching bolt, then remove speed sensor and bracket assembly and position aside. d.
Reverse procedure to install. Install wheel speed sensors by hand. Do not hammer sensors into
position, as damage may result.
3. On all models, remove bolts holding brake caliper to its mounting and insert a fabricated block
(11/16 x 1 1/16 x 2 inches in length) between
brake pads as caliper is being removed. Once removed, caliper can be wired or secured in some
manner away from disc.
4. Remove spindle nut and hub and disc assembly. Grease retainer and inner wheel bearing can
now be removed, Fig. 3. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Drive/Propeller Shafts, Bearings and Joints > Drive/Propeller
Shaft > Component Information > Service and Repair
Drive/Propeller Shaft: Service and Repair
1. Raise and support vehicle. 2. Mark position of shaft in relation to pinion flange for reassembly. 3.
Remove straps securing universal joint to pinion flange, then disconnect shaft from flange. Tape
bearing cups to universal joint to prevent loss
of needle bearings.
4. Slide yoke out of transmission and remove propeller shaft. Insert suitable plug in transmission to
prevent fluid loss. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: >
95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: >
95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6519
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: >
95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6520
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > Recalls for Shift Indicator: >
95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6521
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service
Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service
Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6527
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service
Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6528
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > All Technical Service
Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6529
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > Page 6530
Shift Indicator: Description and Operation
DESCRIPTION
This lamp is used on most models equipped with manual transmission.
OPERATION
The Upshift lamp is illuminated to inform the driver of ideal shift points, with improved fuel economy
as the specific objective. When the light is illuminated, the transmission should be shifted to the
next highest gear, if driving conditions permit such an action.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Lamps and Indicators - Transmission and Drivetrain > Lamps
and Indicators - A/T > Shift Indicator > Component Information > Technical Service Bulletins > Page 6531
Shift Indicator: Service and Repair
If upshift indicator is not working properly, perform the following test. 1. Disconnect ECM connector
C1. 2. Place ignition switch in run. 3. Measure voltage at terminal A2 of ECM connector. 4. If
battery voltage is present, further ECM diagnosis is necessary. 5. If battery voltage is not present,
repair open circuit in brown/black wire, circuit 456.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Manual Transmission/Transaxle > Fluid - M/T > Component
Information > Specifications
Fluid - M/T: Specifications
Fluid Type
........................................................................................................................................................
DEXRON-IIE or DEXRON-III auto. trans.
Capacity
Drain & Refill ........................................................................................................................................
.............................................. 4.7 liters (10.0 pt) Overhaul ..................................................................
.......................................................................................................................... 10.6 liters (22.4 pt)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Locations >
Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Locations >
Component Locations > Page 6542
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Locations >
Component Locations > Page 6543
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6546
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6547
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6548
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6549
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6550
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6551
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6552
Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6553
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component Information > Diagrams > Diagram
Information and Instructions > Page 6554
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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6578
Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Transmission Temperature Sensor/Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Temperature Sensor/Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6604
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6605
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6606
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6607
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6608
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6609
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6610
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6611
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6612
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6613
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams >
Diagram Information and Instructions > Page 6614
Transmission Range Switch Assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Sensors and Switches - Transmission and Drivetrain >
Sensors and Switches - A/T > Transmission Temperature Sensor/Switch, A/T > Component Information > Diagrams > Page
6615
Transmission Temperature Sensor/Switch: Description and Operation
The Transmission Fluid Temperature (TFT) sensor is a thermistor (a device that changes
resistance according to changes in temperature) used to indicate transmission fluid temperature.
High sensor resistance produces high signal input voltage which corresponds to low fluid
temperature. Low sensor resistance produces low signal input voltage which corresponds to high
fluid temperature. The Powertrain Control Module (PCM) uses the TFT sensor signal input to
determine the following:
^ Torque Converter Clutch (TCC) apply and release schedules.
^ Hot mode determination.
^ Shift quality.
The TFT sensor is part of the transmission range fluid pressure switch assembly and is attached to
the control valve body within the transmission. A fault in the Transmission Fluid Temperature (TFT)
sensor circuit will set a DTC 58. 59 or 79.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates
Torque Converter Clutch Solenoid: Technical Service Bulletins A/T - 2-4 Band, TCC Solenoid, 3-4
Clutch Friction/Plates
File In Section: 7 - Transmission
Bulletin No.: 47-71-41
Date: January, 1995
Subject: New 2-4 Band Assembly, 3-4 Clutch Friction and Steel Plates and Torque Clutch PWM
Solenoid
Models: 1995
Buick Roadmaster
1995 Cadillac Fleetwood
1995 Chevrolet Camaro, Caprice, Corvette
1995 Pontiac Firebird
1995 Chevrolet and GMC Truck C/K Models and M/L, G Vans
1994-95 Chevrolet and GMC Truck S/T Models
1994 Oldsmobile Bravada
(1994 Models with RPO +CTF Package)
Transmission Applications: 1995 Hydra-Matic 4L60-E (RPO M30)
A new 2-4 Band Assembly was introduced at the start of production for the 1995 Model Year and
1994 Bravadas and S/T trucks. The 2-4 Band friction material has changed appearance from a
brown material to a gray/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 2-4 Band is
burned/damaged due to its dark color. This dark color is normal. Before replacing the 2-4 Band
inspect it for scoring, chunking or heavily worn friction material.
Before Replacing the Reverse Input Housing and Drum Assembly inspect for scoring or signs of
excessive heat. The 2-4 Band and/or Reverse Input Housing and Drum Assembly should be
replaced ONLY if the above listed damage is found.
Note:
The new 2-4 Band Assembly will NOT service past model Hydra-Matic 4L60-E or 4L60
transmissions.
A new 3-4 clutch friction plate was introduced at the start of production for the 1995 Model Year
and 1994 Bravadas and S/T Trucks. The 3-4 clutch plate friction material has changed appearance
from a brown material to a green/black material. This change was made to enhance durability.
When servicing a 1995 Hydra-Matic 4L60-E transmission, do NOT assume that the 3-4 clutch
friction plates are burned/damaged due to their dark color. This dark color is normal. Before
replacing the 3-4 clutch friction plates inspect for scoring, chunking or heavily worn friction material.
Before replacing the 3-4 clutch steel plates inspect for scoring or signs of excessive heat. The 3-4
clutch friction plates and/or 3-4 clutch steel plates should be replaced ONLY if the above listed
damage is found.
Note:
The new 3-4 friction plates will NOT service past model Hydra-Matic 4L60-E or 4L60 transmissions.
A new Torque Converter Clutch PWM Solenoid was introduced at the start of production for the
1995 Model Year and 1994 Bravadas and S/T trucks. The new torque converter clutch PWM
solenoid is used to control fluid acting on the converter clutch valve, which then controls TCC apply
and release. The solenoid is attached to the control valve body assembly within the transmission.
The TCC PWM solenoid is used to provide smooth engagement of the torque converter by
operating on a negative duty cycle percent of "ON" time.
It a fault is detected in the TCC PWM circuit, DTC 83 will set.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6623
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > A/T - 2-4 Band, TCC Solenoid, 3-4 Clutch Friction/Plates > Page 6624
Included is a Service Manual update for the 1-2 and 3-4 accumulator spring color chart. Replace
these pages in your 1995 Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Actuators and Solenoids Transmission and Drivetrain > Actuators and Solenoids - A/T > Torque Converter Clutch Solenoid, A/T > Component
Information > Technical Service Bulletins > Page 6625
Torque Converter Clutch Solenoid: Service and Repair
REPLACE
1. Raise and support vehicle. 2. Disconnect heated oxygen sensor. 3. Remove catalytic converter
to muffler attaching bolts and nuts. 4. Remove catalytic converter hanger to catalytic converter
bolts. 5. Remove righthand side dampener assembly. 6. Remove nuts holding exhaust pipe to
exhaust manifold. 7. Remove converter and pipe assembly from vehicle. 8. Remove oil pan and oil
filter assembly. 9. Disconnect external wiring harness from transmission pass through connector.
10. Remove accumulator cover attaching bolts. 11. Remove 1-2 accumulator cover, piston and
spring. 12. Disconnect electrical connectors. 13. Remove pressure control solenoid retainer bolt,
then the retainer and solenoid. 14. Remove TCC solenoid retaining bolts. 15. Remove
pass-through electrical connector from transmission case by positioning the small end of power
piston seal protector and diaphragm
retainer installer tool No. J-28458 or equivalent, over the top of the connector, then twist tool to
release the four tabs while at the same time pulling the harness through the case.
16. Remove TCC solenoid with wiring harness from transmission case. 17. Reverse procedure to
install, noting the following:
a. Tighten TCC solenoid retaining bolt to specification. b. Tighten pressure control solenoid
retaining bolt to specification. c. When installing 1-2 accumulator piston to accumulator cover, the
piston legs must face towards the case. d. Tighten accumulator attaching bolts to specification
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
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Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6636
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6637
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage Adjustment > Page 6638
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment > Page 6644
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment > Page 6645
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control Linkage
Adjustment > Page 6646
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Page 6647
Shift Indicator: Description and Operation
DESCRIPTION
This lamp is used on most models equipped with manual transmission.
OPERATION
The Upshift lamp is illuminated to inform the driver of ideal shift points, with improved fuel economy
as the specific objective. When the light is illuminated, the transmission should be shifted to the
next highest gear, if driving conditions permit such an action.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Lamps and Indicators Transmission and Drivetrain > Lamps and Indicators - A/T > Shift Indicator > Component Information > Technical Service
Bulletins > Page 6648
Shift Indicator: Service and Repair
If upshift indicator is not working properly, perform the following test. 1. Disconnect ECM connector
C1. 2. Place ignition switch in run. 3. Measure voltage at terminal A2 of ECM connector. 4. If
battery voltage is present, further ECM diagnosis is necessary. 5. If battery voltage is not present,
repair open circuit in brown/black wire, circuit 456.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Locations > Component Locations
Transmission Position Switch/Sensor: Component Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Locations > Component Locations > Page 6655
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Locations > Component Locations > Page 6656
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions
Transmission Position Switch/Sensor: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 6659
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 6660
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information > Diagrams > Diagram Information and Instructions > Page 6661
Fig.1-Symbols (Part 1 Of 3)
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Information > Diagrams > Diagram Information and Instructions > Page 6662
Fig.2-Symbols (Part 2 Of 3)
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Information > Diagrams > Diagram Information and Instructions > Page 6663
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 6664
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Chevrolet Workshop Manuals > Transmission and Drivetrain > Transmission Control Systems > Sensors and Switches Transmission and Drivetrain > Sensors and Switches - A/T > Transmission Position Switch/Sensor, A/T > Component
Information > Diagrams > Diagram Information and Instructions > Page 6665
Transmission Position Switch/Sensor: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Information > Diagrams > Diagram Information and Instructions > Page 6666
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Park/Neutral Position Switch.
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Transmission Position Switch/Sensor: Description and Operation
The Park/Neutral Position (PNP) switch indicates to the Powertrain Control Module (PCM) when
the transmission is in park, neutral or drive. This information is used for the Torque Converter
Clutch (TCC), Exhaust Gas Recirculation (EGR) and the Idle Air Control (IAC) valve operation.
CAUTION: Vehicle should not be driven with park/neutral position switch disconnected, as idle
quality will be affected and a possible false Diagnostic Trouble Code (DTC) 24 (Vehicle speed
Sensor) may set.
The PNP switch is part of the neutral/start and backup light switch assembly. Refer to CHART
C-1A for PNP switch check.
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Transmission Temperature Sensor/Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Transmission Temperature Sensor/Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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Information > Diagrams > Diagram Information and Instructions > Page 6717
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Information > Diagrams > Diagram Information and Instructions > Page 6718
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Information > Diagrams > Diagram Information and Instructions > Page 6719
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Information > Diagrams > Diagram Information and Instructions > Page 6720
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Information > Diagrams > Diagram Information and Instructions > Page 6721
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Information > Diagrams > Diagram Information and Instructions > Page 6722
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Information > Diagrams > Diagram Information and Instructions > Page 6723
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information > Diagrams > Diagram Information and Instructions > Page 6724
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Information > Diagrams > Diagram Information and Instructions > Page 6725
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information > Diagrams > Diagram Information and Instructions > Page 6726
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information > Diagrams > Diagram Information and Instructions > Page 6727
Transmission Range Switch Assembly.
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Information > Diagrams > Page 6728
Transmission Temperature Sensor/Switch: Description and Operation
The Transmission Fluid Temperature (TFT) sensor is a thermistor (a device that changes
resistance according to changes in temperature) used to indicate transmission fluid temperature.
High sensor resistance produces high signal input voltage which corresponds to low fluid
temperature. Low sensor resistance produces low signal input voltage which corresponds to high
fluid temperature. The Powertrain Control Module (PCM) uses the TFT sensor signal input to
determine the following:
^ Torque Converter Clutch (TCC) apply and release schedules.
^ Hot mode determination.
^ Shift quality.
The TFT sensor is part of the transmission range fluid pressure switch assembly and is attached to
the control valve body within the transmission. A fault in the Transmission Fluid Temperature (TFT)
sensor circuit will set a DTC 58. 59 or 79.
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Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > ABS Light >
Component Information > Description and Operation
ABS Light: Description and Operation
This lamp will be illuminated when the ignition switch is placed in the ON position. The lamp may
be illuminated for as long as 30 seconds as a bulb and system check. If lamp remains illuminated
or comes on while operating the vehicle, a problem in the anti-lock brake system is indicated.
When lamp is illuminated, place ignition switch in OFF position, then restart engine. If lamp still
remains illuminated, the anti-lock brake system should be serviced. The brake system will remain
functional, but without the anti-lock function. After servicing the anti-lock brake system the lamp will
automatically reset. On some models it may be necessary to operate vehicle at a speed over 18
mph to reset lamp.
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Relay > Component Information > Service and Repair
ABS Main Relay: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Remove ABS modulator protective cover. 3. Remove relay
from modulator. 4. Reverse procedure to install.
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Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Brake Fluid
Pump > Component Information > Locations
Brake Fluid Pump: Locations
The pump motor located in the modulator circulates brake fluid back to the master cylinder circuit
during anti-lock braking.
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Pump > Component Information > Locations > Page 6740
Brake Fluid Pump: Description and Operation
DESCRIPTION
The pump motor located in the modulator circulates brake fluid back to the master cylinder circuit
during anti-lock braking.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Electronic
Brake Control Module > Component Information > Locations
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Brake Control Module > Component Information > Locations > Page 6744
Brake Pressure Modulator Valve (BPMV) (With Electronic Brake Control Module (EBCM))
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Brake Control Module > Component Information > Locations > Page 6745
Electronic Brake Control Module: Description and Operation
DESCRIPTION
The EBCM is a small control computer located under the trim panel on the lefthand side of the
passenger compartment on wagon models, and on the lefthand side of the luggage compartment
on sedan models. This computer monitors the speed of each wheel and the electrical status of the
hydraulic modulator. The primary functions of EBCM are to detect wheel locking, control the brake
function while in anti-lock mode and monitor system for correct electrical operation. The EBCM also
controls the display of the ABS diagnostic trouble codes. If the EBCM detects a fault, it can disable
the ABS system and activate the ABS warning lamp.
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Brake Control Module > Component Information > Locations > Page 6746
Electronic Brake Control Module: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Disconnect EBCM electrical connector. 3. Remove two
EBCM to bracket attaching nuts, then the EBCM from the vehicle. 4. Reverse procedure to install,
perform ABS system check as described in System Diagnosis. See: Testing and Inspection
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Control Assembly - Antilock Brakes > Component Information > Locations > ABS Solenoid Valves
Hydraulic Control Assembly - Antilock Brakes: Locations ABS Solenoid Valves
The solenoid valves are located inside the hydraulic modulator are not serviceable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Control Assembly - Antilock Brakes > Component Information > Locations > ABS Solenoid Valves > Page 6751
Hydraulic Control Assembly - Antilock Brakes: Locations Brake Pressure Modulator
The hydraulic modulator (also known as Brake Pressure Modulator (BPM) or Pressure Modulator
Valve (PMV)) is located on the front lefthand side of the engine compartment.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Control Assembly - Antilock Brakes > Component Information > Locations > ABS Solenoid Valves > Page 6752
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Control Assembly - Antilock Brakes > Component Information > Locations > Page 6753
Hydraulic Control Assembly - Antilock Brakes: Diagrams
Brake Pressure Modulator Valve (BPMV)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Control Assembly - Antilock Brakes > Component Information > Locations > Page 6754
Brake Pressure Modulator Valve (BPMV) (With Electronic Brake Control Module (EBCM))
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Control Assembly - Antilock Brakes > Component Information > Description and Operation > ABS Solenoid Valves
Hydraulic Control Assembly - Antilock Brakes: Description and Operation ABS Solenoid Valves
DESCRIPTION
The solenoid valves are located inside the hydraulic modulator are not serviceable. The solenoid
valves increase, decrease or maintain the brake fluid pressure to the wheel circuits. During
anti-lock braking the valves are controlled by signals received by the EBCM/EBTCM. During
normal braking, the valves are positioned in a pressure increase or open position.
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Control Assembly - Antilock Brakes > Component Information > Description and Operation > ABS Solenoid Valves > Page
6757
Hydraulic Control Assembly - Antilock Brakes: Description and Operation Hydraulic Modulator
Valve
DESCRIPTION
The hydraulic modulator (also known as Brake Pressure Modulator (BPM) or Pressure Modulator
Valve (PMV)) is located on the front lefthand side of the engine compartment, provides brake fluid
modulation for each individual wheel circuit as required during anti-lock braking. During anti-lock
braking, the modulator can maintain or reduce brake fluid pressure independent of the pressure
generated in the master cylinder.
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Control Assembly - Antilock Brakes > Component Information > Description and Operation > Page 6758
Hydraulic Control Assembly - Antilock Brakes: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Disconnect and remove air intake duct and resonator, then
position upper coolant hose aside. 3. Disconnect canister purge line at canister and position aside.
4. Remove modulator valve cover attaching screw and cover. 5. Disconnect modulator valve
electrical connector and ground wire. 6. Disconnect all hydraulic lines to modulator valve, then plug
pipes to prevent loss of fluid and fluid contamination. Note location of pipes for
installation reference.
7. Remove three modulator valve to bracket attaching nuts, then the modulator valve from vehicle.
8. Reverse procedure to install, then perform ABS system check as described in System
Diagnosis. See: Testing and Inspection
NOTE: Ensure brake hydraulic pipes are installed correctly. Pipes that are crossed during
installation could cause wheel lock-up.
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Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front
Wheel Speed Sensor: Locations Wheel Speed Sensor Lead, Front
LH Rear Engine Compartment
LH Front Frame Rail
RH Front Frame Rail
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 6763
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 6764
Wheel Speed Sensor: Locations Wheel Speed Sensor, Rear
LH Rear Frame Rail (Without Automatic Level Control)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 6765
Antilock Brake System Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Locations > Page 6766
Wheel Speed Sensor: Description and Operation
DESCRIPTION
These sensors transmit wheel speed information to the EBCM using a small amount of AC voltage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor
Wheel Speed Sensor: Service and Repair Left Front Wheel Speed Sensor
REPLACEMENT
1. Raise and support vehicle. 2. Disconnect wheel speed sensor harness connector and sensor
assembly connector from clip. 3. Disconnect speed sensor connector from harness connector. 4.
Remove sensor bracket attaching bolt from frame rail. 5. Disconnect wheel speed sensor assembly
harness with grommets from brackets and combination valve brake pipe clip. Note position of
grommets and harness for installation reference.
6. Remove speed sensor retaining bolt, then the speed sensor from steering knuckle. 7. Reverse
procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the knuckle and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor > Page 6769
Wheel Speed Sensor: Service and Repair Rear Axle Speed Sensor
1. Raise and support vehicle.
2. Unclip sensor assembly connector and differential sensor connector, then separate the
connectors.
3. Disconnect speed sensor harness assembly wiring harness with gromments from sensor
bracket. Note position of grommets and harness for installation reference.
4. Remove sensor attaching bolt, then the sensor from the vehicle.
5. Reverse procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the axle housing and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Antilock Brakes / Traction Control Systems > Wheel Speed
Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor > Page 6770
Wheel Speed Sensor: Service and Repair Right Front Wheel Speed Sensor
REPLACEMENT
1. Disconnect forward lamp harness wheel speed sensor connector and wheel speed sensor
assembly connector from clip. 2. Disconnect forward lamp harness connector from wheel speed
sensor connector. 3. Raise and support vehicle. 4. Remove sensor bracket attaching bolt from
frame rail. 5. Remove sensor assembly harness with grommets from brackets. Note position of
grommets and harness for assembly reference. 6. Remove sensor retaining bolt, then the sensor
from vehicle. 7. Reverse procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the knuckle and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Bleeding > System Information > Service and Repair >
With ABS System
Brake Bleeding: Service and Repair With ABS System
Manual Bleeding
Fig. 210 Brake System Manual Bleed.
NOTE: Pressure bleeding is recommended for all hydraulic systems. However, if a pressure
bleeder is unavailable, use the following procedure.
CAUTION: Brake fluid damages painted surfaces. Immediately clean any spilled fluid.
1. Remove vacuum reserve by pumping brakes several times with engine off. 2. Fill master cylinder
reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let
reservoir fall below half full. 3. If necessary, bleed master cylinder as follows:
a. Disconnect master cylinder forward brake line connection until fluid flows from reservoir.
Reconnect and tighten brake line. b. Instruct an assistant to slowly depress brake pedal one time
and hold. c. Crack open front brake line connection again, purging air from cylinder. d. Retighten
connection and slowly release brake pedal. e. Wait 15 seconds, then repeat until all air is purged. f.
Bleed the rearward (nearest the cowl) brake line connection by repeating preceding steps.
4. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 5. Proceed to appropriate wheel first and follow set sequence according
to Wheel Bleed Sequence. See: Wheel Bleed Sequence 6. Place transparent tube over bleeder
valve, then allow tube to hang down into transparent container, Fig. 210. Ensure end of tube is
submerged in
clean brake fluid.
7. Instruct an assistant to slowly depress brake pedal one time and hold. 8. Crack open bleeder
valve, purging air from cylinder. Retighten bleeder screw and slowly release pedal. 9. Wait 15
seconds, then repeat preceding bleed steps. Repeat these steps until all air is bled from system.
Pressure Bleeding
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Bleeding > System Information > Service and Repair >
With ABS System > Page 6775
Fig. 210 Brake System Manual Bleed.
Fig. 21 Installing Pressure Bleeder Adapter
1. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 2. Using a diaphragm type pressure bleeder, install suitable bleeder
adapter to master cylinder, Fig. 211. 3. Charge bleeder ball to 20-25 psi. 4. Connect pressure
bleeder line to adapter. 5. Open line valve on pressure bleeder, then depress bleed-off valve on
adapter until a small amount of brake fluid is released. 6. Raise and support vehicle. 7. Proceed to
appropriate wheel first and follow set sequence according to Wheel Bleeding Sequence. See:
Wheel Bleed Sequence 8. Place transparent tube over bleeder valve, then allow tube to hang down
into transparent container, Fig. 210. Ensure end of tube is submerged in
clean brake fluid.
9. Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from
line.
Wheel Bleed Sequence
If manual bleeding, RR-LR-RF-LF; if pressure bleeding, bleed front brakes together and rear
brakes together.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Bleeding > System Information > Service and Repair >
With ABS System > Page 6776
Brake Bleeding: Service and Repair Without ABS System
Manual
Fig. 210 Brake System Manual Bleed.
NOTE: Pressure bleeding is recommended for all hydraulic systems. However, if a pressure
bleeder is unavailable, use the following procedure. Brake fluid damages painted surfaces.
Immediately clean any spilled fluid.
1. Remove vacuum reserve by pumping brakes several times with engine off. 2. Fill master cylinder
reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let
reservoir fall below half full. 3. If necessary, bleed master cylinder as follows:
a. Disconnect master cylinder forward brake line connection until fluid flows from reservoir.
Reconnect and tighten brake line. b. Instruct an assistant to slowly depress brake pedal one time
and hold. c. Crack open front brake line connection again, purging air from cylinder. d. Retighten
connection and slowly release brake pedal. e. Wait 15 seconds, then repeat until all air is purged. f.
Bleed the rearward (nearest the cowl) brake line connection by repeating steps a through e.
4. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 5. Proceed to appropriate wheel first and follow set sequence according
to Wheel Bleeding Sequence. 6. Place transparent tube over bleeder valve, then allow tube to
hang down into transparent container, Fig. 16. Ensure end of tube is submerged in
clean brake fluid.
7. Instruct an assistant to slowly depress brake pedal one time and hold. 8. Crack open bleeder
valve, purging air from cylinder. Retighten bleeder screw and slowly release pedal. 9. Wait 15
seconds, then repeat steps 7 and 8. Repeat these steps until all air is bled from system.
Pressure
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Bleeding > System Information > Service and Repair >
With ABS System > Page 6777
Fig. 21 Installing Pressure Bleeder Adapter
Fig. 210 Brake System Manual Bleed.
1. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 2. Using a diaphragm type pressure bleeder, install suitable bleeder
adapter to master cylinder, Fig. 17. 3. Charge bleeder ball to 20-25 psi. 4. Connect pressure
bleeder line to adapter. 5. Open line valve on pressure bleeder, then depress bleed-off valve on
adapter until a small amount of brake fluid is released. 6. Raise and support vehicle. 7. Proceed to
appropriate wheel first and follow set sequence according to Wheel Bleeding Sequence. 8. Place
transparent tube over bleeder valve, then allow tube to hang down into transparent container, Fig.
16. Ensure end of tube is submerged in
clean brake fluid.
9. Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from
line.
Front Disc Brakes
NOTE: Pressure bleeding is recommended for all hydraulic disc brake systems.
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. On
vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid
level in master cylinder during bleeding operation.
Never use brake fluid that has been drained from hydraulic system when bleeding the brakes. Be
sure the disc brake pistons are returned to their normal positions and that the shoe and lining
assemblies are properly seated. Before driving the vehicle, check brake operation to be sure that a
firm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Bleeding > System Information > Service and Repair >
With ABS System > Page 6778
pedal has been obtained.
Rear Disc Brakes
NOTE: Pressure bleeding is recommended for all hydraulic disc brake systems.
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. On
vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid
level in master cylinder during bleeding operation.
Never use brake fluid that has been drained from hydraulic system when bleeding the brakes. Be
sure the disc brake pistons are returned to their normal positions and that the shoe and lining
assemblies are properly seated. Before driving the vehicle, check brake operation to be sure that a
firm pedal has been obtained.
Wheel Bleeding Sequence
Rear wheel drive models: if manual bleeding, RR-LR-RF-LF; if pressure bleeding, bleed front
brakes together and rear brakes together. Front wheel drive models: RR-LF-LR-RF
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions
Brake Warning Indicator: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6783
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6784
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6785
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6786
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6787
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6788
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6789
Brake Warning Indicator: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Diagrams > Diagram Information and Instructions > Page 6790
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Diagrams > Diagram Information and Instructions > Page 6791
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Diagrams > Diagram Information and Instructions > Page 6792
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Diagrams > Diagram Information and Instructions > Page 6793
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6808
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6809
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6810
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6811
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6812
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6813
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Diagrams > Diagram Information and Instructions > Page 6814
Brake Warning System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Description and Operation > Brake Warning System
Brake Warning Indicator: Description and Operation Brake Warning System
DESCRIPTION
The "Brake" warning indicator will be illuminated when a low brake fluid level in the master cylinder
is sensed or when the Electronic Brake Control Module (EBCM) lights it in response to certain
diagnostic trouble codes.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Description and Operation > Brake Warning System > Page 6817
Brake Warning Indicator: Description and Operation Circuit Operation
Voltage is applied to the "BRAKE" Indicator from I/P Fuse #11 when the Ignition Switch is turned to
"RUN," "BULB TEST" or "START." The "BRAKE" Indicator is controlled by any one of three
switches: the Brake Pressure Switch, Ignition Switch or Park Brake Indicator Switch. When the
Ignition Switch is turned to "BULB TEST" or "START," CKT 209 is grounded through the Ignition
Switch to activate the "BRAKE" Indicator. When the Brake Pressure Switch is closed, CKT 209 is
grounded through the contacts of the Brake Pressure Switch to activate the "BRAKE" Indicator.
CKT 33 is grounded through the Park Brake Switch when the Park Brake is set, to activate the
"BRAKE" Indicator. With the Daytime Running Lamps (DRL) Control Module grounded through
CKT 33, the module provides ground to CKT 209, lighting the "BRAKE" Indicator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information >
Description and Operation > Brake Warning System > Page 6818
Brake Warning Indicator: Description and Operation Brake Pressure Warning Lamp
DESCRIPTION
The warning lamp should illuminate when the ignition switch is in the start position, and turn off
when the switch returns to run. If the brake lamp remains on after the ignition returns to run, check
fluid level in master cylinder reservoir and inspect parking brake. If the warning lamp does not turn
on during cranking, check for defective bulb or blown fuse.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information > Testing
and Inspection > Initial Inspection and Diagnostic Overview
Brake Warning Indicator: Initial Inspection and Diagnostic Overview
Circuit Operation
Voltage is applied to the "BRAKE" Indicator from I/P Fuse #11 when the Ignition Switch is turned to
"RUN," "BULB TEST" or "START." The "BRAKE" Indicator is controlled by any one of three
switches: the Brake Pressure Switch, Ignition Switch or Park Brake Indicator Switch. When the
Ignition Switch is turned to "BULB TEST" or "START," CKT 209 is grounded through the Ignition
Switch to activate the "BRAKE" Indicator. When the Brake Pressure Switch is closed, CKT 209 is
grounded through the contacts of the Brake Pressure Switch to activate the "BRAKE" Indicator.
CKT 33 is grounded through the Park Brake Switch when the Park Brake is set, to activate the
"BRAKE" Indicator. With the Daytime Running Lamps (DRL) Control Module grounded through
CKT 33, the module provides ground to CKT 209, lighting the "BRAKE" Indicator.
System Diagnosis
^ Perform the System Check and refer to the Symptom Table for the appropriate diagnostic
procedure(s). See: System Check See: Symptom Related Diagnostic Procedures/Symptom Table
System Check
Troubleshooting Hints
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Check I/P Fuse Block Fuse #11. If Fuse #11 is open check for a short to ground in CKT 39. 2.
Check brake fluid level. If low, refer to Antilock Brake System. See: Antilock Brakes / Traction
Control Systems ^
Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures."). See: Diagrams/Diagnostic Aids
^ Refer to System Diagnosis. See: System Diagnosis
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information > Testing
and Inspection > Initial Inspection and Diagnostic Overview > Page 6821
Brake Warning Indicator: Symptom Related Diagnostic Procedures
Symptom Table
Chart #1 Ignition Switch Does Not Activate The BRAKE Indicator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information > Testing
and Inspection > Initial Inspection and Diagnostic Overview > Page 6822
Chart #2 Park Brake Does Not Activate The BRAKE Indicator (Base Or Twilight Sentinel)
Chart #3 Park Brake Does Not Activate The BRAKE IND (With DRL)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information > Testing
and Inspection > Initial Inspection and Diagnostic Overview > Page 6823
Chart #4 BRAKE IND Stay ON W/IGN SW In RUN & Park Brake Released (Base/Twilight Sentinel)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information > Testing
and Inspection > Initial Inspection and Diagnostic Overview > Page 6824
Chart #4 BRAKE IND Stays ON W/IGN SW In RUN & Park Brake Released (W/DRL)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Brake Warning Indicator > Component Information > Testing
and Inspection > Page 6825
Brake Warning Indicator: Service and Repair
This lamp will be illuminated when the ignition switch is placed in the ON position. The lamp may
be illuminated for as long as 30 seconds as a bulb and system check. If lamp remains illuminated
or comes on while operating the vehicle, a problem in the anti-lock brake system is indicated.
When lamp is illuminated, place ignition switch in OFF position, then restart engine. If lamp still
remains illuminated, the anti-lock brake system should be serviced. The brake system will remain
functional, but without the anti-lock function. After servicing the anti-lock brake system the lamp will
automatically reset. On some models it may be necessary to operate vehicle at a speed over 18
mph to reset lamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Specifications > Bore Diameter
Brake Caliper: Specifications Bore Diameter
Caliper Bore Diameter 2.94 in
Caliper Bore Diameter 2.126 in
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Specifications > Bore Diameter > Page 6831
Brake Caliper: Specifications Tightening Specifications
Brake Hose To Caliper 30 ft.lb
Caliper Bleeder Screw 7 ft.lb
Front Caliper Mounting Bracket 166 ft.lb
Rear Bracket Mounting Bolt 70 ft.lb
Rear Lower Guide Pin Bolt 16 ft.lb
Rear Pivot Pin Nut 16 ft.lb
Rear Upper Guide Pin Bolt 26 ft.lb
Brake Hose To Caliper 33 ft.lb
Caliper Bleeder Screw 115 ft.lb
Caliper Mounting Bolts 38 ft.lb
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes
Brake Caliper: Service and Repair Front Disc Brakes
Removal/Installation
Fig. 3 Piston Compressing W/C-Clamp
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6834
Fig. 4 Caliper & Mounting Bolts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6835
Fig. 8 Caliper & Stops Clearance Inspection
REMOVAL
1. Siphon enough brake fluid out of master cylinder to bring fluid level to 1/3 full to avoid fluid
overflow when caliper piston is pushed back into its
bore.
2. Raise vehicle and remove front wheels. 3. Using a C-clamp, as illustrated in Fig. 3, push piston
back into its bore. 4. If caliper assembly is to be serviced, remove inlet fitting attaching bolt, copper
washer, and inlet fitting from caliper housing. Plug opening in inlet
fitting to prevent fluid loss and contamination. Do not crimp brake hose, as this may damage
internal structure of hose. If only shoe and lining assemblies are to be replaced, do not disconnect
brake line fitting from caliper.
5. Remove two mounting bolts, Fig. 4, and lift caliper away from disc. If only shoe and lining
assemblies are to be replaced, suspend caliper from
chassis using suitable hanger. Do not allow caliper to hang by brake hose.
INSTALLATION
1. Position caliper over disc, lining up holes in caliper with holes in mounting bracket. If brake hose
was not disconnected during removal, be sure
not to kink it during installation.
2. Start mounting bolts through sleeves in inboard caliper ears and mounting bracket, making sure
ends of bolts pass under ears on inboard shoe.
Right and left calipers must not be interchanged.
3. Push mounting bolts through to engage holes in outboard ears. Then thread mounting bolts into
bracket. 4. Tighten mounting bolts to specifications. 5. Check dimensions between each caliper
stop and caliper, Fig. 8. 6. If brake hose was removed, reconnect it and bleed calipers. 7. Replace
front wheels, lower vehicle and add brake fluid to master cylinder to bring level to 1/4 inch from top.
Before moving vehicle, pump
brake pedal several times to be sure it is firm. Do not move vehicle until a firm pedal is obtained.
On some models with low drag calipers, apply approximately 175 pounds of pressure to brake
pedal three times to properly seat caliper and related components.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6836
Disassemble/Assemble
Fig. 5 Caliper Piston Removal.
Fig. 6 Boot To Piston Installation.
Fig. 7 Boot To Caliper Piston
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6837
DISASSEMBLE
1. Remove caliper. Refer to Removal/Installation. 2. Clean outside of caliper, then drain brake fluid
from caliper. 3. Use clean shop towels to pad interior of caliper assembly, then remove piston by
directing compressed air into caliper brake hose inlet hole, Fig. 5.
Use just enough air pressure to ease piston out of bore. Do not place fingers in front of piston for
any reason when applying compressed air. This could result in serious personal injury.
4. Carefully pry dust boot out of bore. 5. Using a small piece of wood or plastic, remove piston seal
from bore. Do not use a metal tool of any kind to remove seal as it may damage
bore.
6. Remove bleeder valve. 7. Inspect piston for scoring, nicks, corrosion, and wear and replace as
needed. 8. Inspect caliper housing and seal groove for corrosion, nicks, scoring and excessive
wear, and use crocus cloth to polish away corrosion from
housing bore. Replace caliper housing if corrosion in and around seal groove will not clean up with
crocus cloth.
9. Clean all parts with denatured alcohol. Dry with unlubricated compressed air. Blow out all
passages in housing and bleeder valve.
ASSEMBLE
1. Lubricate caliper piston bore and new piston seal with clean brake fluid. Position seal in bore
groove. Ensure seal is not twisted. 2. Lubricate piston with clean brake fluid and assemble a new
boot into groove in piston so the fold faces the open end of piston, Fig. 6. 3. Using care not to
unseat seal, insert piston into bore and force piston to the bottom of bore. 4. Position dust boot in
caliper counterbore and install, using suitable seal installer, Fig. 7. Check boot installation to be
sure retaining ring
molded into boot is not bent and that boot is installed below caliper face and evenly all around. If
boot is not fully installed, dirt and moisture may enter bore and cause corrosion.
5. Install brake hose in caliper using a new copper gasket. 6. Install shoes and reinstall caliper
assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6838
Brake Caliper: Service and Repair Rear Disc Brakes
Removal/Installation
Fig. 3 Disabling Parking Brake Automatic Adjuster Mechanism
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6839
Fig. 1 Exploded View Of PBR Single Piston Rear Caliper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6840
Fig. 4 Parking Brake Free Travel Adjustment
REMOVAL
1. Disable parking brake automatic adjuster as follows:
a. Working from inside vehicle, remove driver seat cushion, then the parking brake lever cover
screws and cover. b. Using 0.080 inch gauge wire, fabricate a tool to disengage drive pawl from
sector, Fig. 3. c. Using tool mentioned above, disengage drive pawl from sector, then insert a nail
through anchor plate to keep drive pawl in disengaged
position.
d. Pull up on lever until it aligns with pawl, then depress button until lever is fully downward. e.
Visually inspect that anchor plate is fully against stud. If not, repeat procedure as needed. f.
Pull front parking brake cable rearward to slacken cable at caliper assembly.
2. Raise and support vehicle, then remove tire and wheel assembly. 3. Install two wheel retaining
nuts to retain rotor in position. 4. If caliper requires overhaul, remove inlet fitting attaching bolt, then
disconnect inlet fitting from caliper housing. Discard the two gaskets, then
plug openings in inlet fitting and caliper to prevent loss or contamination of fluid.
5. Remove caliper lever return spring. Discard spring if coils are open. 6. Disconnect parking brake
cable from lever (5) and caliper bracket (8), Fig. 1. 7. Remove upper and lower guide pin bolts,
then remove caliper from rotor and mounting bracket. If caliper does not require overhaul, suspend
it
from suspension to prevent damage to brake line.
INSTALLATION
1. Install shoe and lining assemblies, if removed, as outlined previously. 2. Position caliper over
rotor and onto mounting bracket, then install upper and lower guide pin bolts. Torque upper bolt to
26 ft. lbs. and lower bolt
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6841
to 16 ft. lbs.
3. Attach parking brake cable to caliper bracket and lever, then install lever return spring. 4. If
removed, install inlet fitting using new gaskets, then bleed brake system. 5. If caliper was
overhauled, adjust parking brake free travel as follows:
a. Have an assistant apply a light load to brake pedal until rotor can no longer be turned by hand.
b. Apply pressure to caliper lever in direction shown in Fig. 4. c. Measure free travel between
caliper lever and housing. Free travel should be 0.024-0.028 inch. If free travel is not as specified,
proceed to next
step.
d. Remove adjustment screw, then clean thread adhesive from threads. e. Coat threads with new
adhesive, reinstall adjustment screw, then turn as required until specified free travel is obtained.
Turning screw
clockwise increases free travel, while counterclockwise rotation decreases travel.
f. Release brake pedal, then firmly apply brake pedal three times and recheck free travel. Repeat
adjustment procedure as necessary.
6. Remove nail from anchor plate installed during caliper removal procedure. 7. Apply and release
parking brake three times, then lift lever upward and ensure parking brake fully engages at 7-9
clicks. 8. Release parking brake. No brake drag should exist and no gap between caliper housings
and parking levers should be evident. 9. Install parking brake lever cover, screws and driver's
cushion.
10. Reinstall tire and wheel assembly, then check and refill master cylinder as required. 11. Start
engine and pump brake pedal several times to seat brake linings.
Disassemble/Assemble
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6842
Fig. 1 Exploded View Of PBR Single Piston Rear Caliper
DISASSEMBLE
1. Remove caliper. Refer to Removal/Installation. 2. Remove the two return springs from actuating
collar, then pull collar out of caliper housing and remove clamp rod (28) and bushing (27), Fig. 1.
discard bushing.
3. Bend back boot retainer tabs, then remove retainers (21, 31), boots (20, 25) and pushrod (22)
from actuating collar. Remove preload spring (23)
from retainer (31), then discard retainers and boots.
4. Use clean shop towels to pad interior of caliper assembly, then remove piston by directing
compressed air into caliper brake hose inlet hole, Use
just enough air pressure to ease piston out of bore. Do not place fingers in front of piston for any
reason when applying compressed air. This could result in serious personal injury.
5. Using a small piece of wood or plastic, remove piston seal from bore. Do not use a metal tool of
any kind to remove seal as it may damage
bore.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6843
6. Remove bleeder valve cap and bleeder valve. 7. Remove seal (1), sprag clip (2) and lever (5)
from pivot pin (3). Discard sprag clip. 8. Clean all metal components with suitable solvent, then dry
with compressed air. 9. Inspect parking brake lever components, piston, caliper bore and mounting
bracket for scoring, excessive wear or corrosion. Replace parts as
necessary.
CALIPER ASSEMBLE
1. Using clean brake fluid, lubricate piston seal, then install seal into caliper bore groove. Ensure
seal is not twisted during installation. 2. Using clean brake fluid, lubricate caliper bore and piston. 3.
Place piston into caliper bore, then push downward until fully bottomed in bore. 4. Apply lubricant
provided in repair kit to actuating collar (24), then install pushrod (22), new boots (20, 25) and new
retainers (21, 31) onto collar,
Fig. 1. Clamp retainers firmly against collar, then bend tabs on retainer (21) to hold assembly
together.
5. Reconnect preload spring (23) onto retainer (31). 6. Apply lubricant provided in repair kit to
clamp rod (28), then slide rod through holes in boot (25) and actuating collar (24). Ensure boot is
firmly
positioned against reaction plate on clamp rod.
7. Lubricate new compliance bushing (27), then install bushing onto clamp rod (28). 8. Lubricate
grooved bead of inner boot (20), boot groove in caliper housing and actuating collar with lubricant
provided in repair kit. 9. Push clamp rod to bottom of piston mating hole, then pull actuating collar
(24) and seat inner boot (20) into boot groove in caliper housing.
10. Ensure pushrod (22) is positioned in hole in caliper housing, then install bleeder cap and valve.
11. If removed, install pivot pin (3) and new nut (12) onto caliper, torque nut to 16 ft. lbs., then
lubricate parking brake lever (5) and pivot pin. 12. Install pivot pin seal (1), parking brake lever and
new sprag clip (2), ensuring teeth of sprag clip face away from lever, then snap seal cap over
pivot pin.
13. Install the two collar return springs (26) onto retainer (31). Ensure retainer enters springs at end
of second coil. 14. Install adjustment screw (11) into caliper housing until actuating collar is parallel
to piston bore face of housing. 15. Lubricate guide pins with suitable grease, then slide boots onto
pins. 16. Fill boots with grease, then install into mounting bracket. Ensure boots are properly
positioned in grooves in pins and mounting bracket. 17. Install caliper and bleed brake system,
then adjust parking brake free travel under Adjustments. Refer to Parking Brake System.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Pad > Component Information >
Service and Repair > Front Disc Brakes
Brake Pad: Service and Repair Front Disc Brakes
Fig. 2 Brake Shoe Ear Crimping
REMOVAL
1. Remove caliper assembly from steering knuckle as described in Brake
Caliper/Removal/Installation. 2. Remove inboard shoe. Dislodge outboard shoe and position caliper
on front suspension so the brake hose will not support the weight of the
caliper.
3. Remove shoe support spring from piston. 4. Remove two sleeves from inboard ears of caliper. 5.
Remove four rubber bushings from grooves in each of caliper ears.
INSTALLATION
1. Lubricate new sleeves, rubber bushings, bushing grooves and mounting bolt ends with Delco
Silicone Lube or its equivalent. 2. Install new bushings and sleeves in caliper ears. Position sleeve
so that the end toward the shoe is flush with machined surface of the ear. 3. Install shoe support
spring by positioning single tang end of spring into notch cut at top of inboard shoe. Press
remaining end of spring over
bottom edge of shoe until shoe is engaged securely.
4. Position inboard shoe with spring attached into caliper with ear end facing downward and bottom
end facing upward with spring resting on inside
diameter of piston. Press downward on both ends of shoe until shoe contacts piston and support
spring contacts piston inside diameter. Some inboard replacement brake pads incorporate wear
sensors and have a specific left and righthand assembly. Properly installed, wear sensor will face
toward rear of caliper.
5. Position outboard shoe in caliper with shoe ears over caliper ears and tab at bottom of shoe
engaged in caliper cutout. 6. With shoes installed, lift caliper and rest bottom edge of outboard
lining on outer edge of brake disc to be sure there is no clearance between
outboard shoe tab and caliper abutment.
7. Install caliper and tighten mounting bolts to specifications. 8. Clinch upper ears of outboard shoe
by positioning pliers with one jaw on top of upper ear and one jaw in notch on bottom shoe
opposite ear, Fig.
2. Ears are to be flat against caliper housing with no radial clearance. If clearance exists, repeat
clinching procedure. Before moving vehicle, pump brake pedal several times to be sure it is firm.
Do not move vehicle until a firm pedal is obtained. On some models with low drag calipers, apply
approximately 175 pounds of pressure to brake pedal three times to properly seat caliper and
related components.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Pad > Component Information >
Service and Repair > Front Disc Brakes > Page 6848
Brake Pad: Service and Repair Rear Disc Brakes
Fig. 2 Piston Compressing In Caliper Bore
REMOVAL
1. Remove 2/3 of the total brake fluid capacity from master cylinder reservoir. 2. Raise and support
vehicle, then remove tire and wheel assembly. 3. Install two wheel retaining nuts to retain rotor in
position. 4. Position one end of a suitable C-clamp against inlet fitting bolt, and the other end
against outboard shoe and lining, then tighten clamp as shown,
Fig. 2, until piston fully bottoms in caliper bore.
5. Remove upper guide pin bolt and discard. 6. Loosen lower guide pin bolt, then pivot caliper
downward on lower guide pin bolt to expose shoe & lining assemblies. Use care to avoid damaging
brake hose.
7. Remove shoes and linings from mounting bracket.
INSTALLATION
1. Install outboard shoe and lining onto mounting bracket, ensuring insulator on shoe is positioned
toward caliper housing. 2. Install inboard shoe and lining. Ensure wear sensor is positioned nearest
caliper piston. When properly installed, sensor should be in trailing
position when wheel is rotated in forward direction.
3. Pivot caliper into position over shoes and linings. Ensure springs on outboard shoe do not
protrude through inspection hole in housing. If
protrusion is evident, lift caliper housing and readjust position of outboard shoe and lining.
4. Install new upper guide pin bolt and torque to 26 ft. lbs., then torque lower bolt to 16 ft. lbs. 5. Fill
master cylinder to proper level, then pump brake pedal firmly and slowly three times to bring pads
into contact with brake rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information
Brake Rotor/Disc: Technical Service Bulletins Brakes - Rotor Lateral Runout Correction Information
Bulletin No.: 01-05-23-001B
Date: January 31, 2008
INFORMATION
Subject: Brake Align(R) System for Brake Rotor Lateral Runout Correction
Models: 2008 and Prior Passenger Cars
Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number
01-05-23-001A (Section 05 - Brakes).
This bulletin is being issued to update General Motors position on correcting brake rotor lateral
runout (Refer to Corporate Bulletin Number 00-05-22-002B for additional brake rotor service
procedures).
Certain conditions may apply to individual vehicles regarding specific repairs. Refer to those
specific repairs in applicable service bulletins. Make sure other possible sources of brake pulsation,
such as ABS pedal feedback, have been addressed before checking rotor runout.
Anytime a new or refinished rotor is installed on a vehicle, the rotor must have .050 mm (.002 in) or
less of lateral runout. This specification is important to prevent comebacks for brake pulsation. Until
now, the only acceptable methods to correct brake rotor runout were to index or replace the rotor or
to refinish the rotor using an on-vehicle brake lathe.
GM has approved a new technology for the correction of lateral runout on new or refinished rotors.
This new method is called Brake align(R)*. It will allow the technician to meet the .050 mm (.002 in)
or less requirement for lateral runout by installing a specially selected, tapered correction plate
between the rotor and the hub. The Brake Align(R) Correction system does NOT require the use of
an on-vehicle brake lathe to correct for lateral runout.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such items which may be available from
other sources.
The Brake Align(R) Starter Kit will include an ample supply of Correction Plates, in various
correction sizes, that will cover most current GM passenger car applications. It will also include a
Brake Align(R) tool kit containing a dial indicator and retaining washers along with other useful
tools.
Service Procedure
Follow all the procedures referred to in Corporate Bulletin Number 00-05-22-002B. Dealers who
have purchased the Brake Align(R) Starter Kit may use the following simplified runout correction
procedure:
The existing rotors must first be machined on an approved, well-maintained bench lathe to
guarantee smooth, flat, and parallel surfaces. Should the rotors require replacement, please note
that it is not necessary to machine new rotors.
Make sure all the mating surfaces of the rotor and the hub are clean, using the J 42450-A wheel
Hub Cleaning Kit. Mount the new or refinished rotor onto the vehicle hub using the retaining
washers provided in the kit. Do not reinstall the caliper or wheel at this time.
Tighten all the wheel nuts to the proper specification, using J 39544 Torque Socket or the
equivalent.
Fasten the dial indicator to the steering knuckle so that the indicator needle contacts the rotor
friction surface approximately 12.7 mm (1/2 in) from the rotors outer edge.
Rotate the rotor and observe the total lateral runout.
Index the rotor on the hub to achieve the lowest amount of lateral runout. This will require removal
and reassembly of the rotor until the lowest total lateral runout reading is obtained. If this reading is
.050 mm (.002 in) or less, the assembled rotor is within specification. The brake system may be
reassembled.
If total lateral runout is greater than .050 mm (.002 in), proceed with determining the correct Brake
Align(R) Correction as follows:
Rotate the rotor to locate the lowest dial indicator reading and set the dial to zero. Rotate the rotor
to determine and locate the highest amount of lateral runout.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6853
Note the AMOUNT and LOCATION of the "high spot" on the rotor and mark the closest wheel stud
relative to this location.
Remove the rotor.
Select the appropriate Brake Align(R) Runout Correction Plate for this vehicle using the Application
Chart. Make sure the selection corrects the amount of runout that was diagnosed.
Never attempt to stack two or more Correction Plates together on one hub.
Never attempt to re-use a previously installed Correction Plate.
Following the Brake Align(R) procedures and diagram, install the Correction Plate onto the vehicle
between the hub and the rotor. The V-notch in the Correction Plate is to be installed and aligned
with the noted location of the "high spot" on the vehicle hub and marked wheel stud.
Install the rotor onto the vehicle with the Correction Plate placed between the hub and the rotor. Be
sure to install the rotor onto the hub in the same location as identified in Step 7.
The rotor should then be secured onto the hub and tightened to the proper specification. The rotor
should be dial indicated once more to assure that the rotor is now within specification.
The brake system is now ready for the remaining service and assembly. Once the caliper has been
installed, check to ensure that the rotor rotates freely.
Parts Information
Brake Align(R) Runout Correction Plates are available through the suppliers shown.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6854
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6855
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6856
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6857
Brake Align Order Form
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6858
Brake Rotor/Disc: Technical Service Bulletins Brakes - Rotor & Hub Flange Cleaning Tool Revision
File In Section: 5 - Brakes
Bulletin No.: 73-50-37
Date: January, 1998
INFORMATION
Subject: Revision to J 42450 Tool; Proper Brake Rotor and Hub Flange Surface Cleaning
Models: 1998 and Prior Passenger Cars and Light Duty Trucks - with Disc Brakes (Rotor and Hub
Separate)
This bulletin is being revised to update the following text.
This bulletin is being issued to inform the dealer about a revision to tool J 42450 and reinforce the
need for proper hub flange and brake rotor mating surface cleaning during service.
Tool J 42450 is a cleaning pad arbor and pad system that fits over the wheel stud and cleans the
portion of the hub surface that is very difficult to reach with normal rotary cleaning pads. Tool J
42450 is being revised to J 42450-A to improve the hook and loop material retention. Any dealer
experiencing problems with tool J 42450 should contact Kent-Moore at 1-800-345-2233 for a
revised arbor at no charge.
Anytime the brake rotor has been separated from the hub bearing flange or if rotor machining is
necessary, the rotor and hub should be marked to maintain the original position. Clean the hub
flange of all dirt and foreign material using special tool J 42450 or J 42450-A. Clean both sides of
the brake rotor hub using an aggressive (80 grit) abrasive sanding pad on a rotary disc.
Properly cleaning the rotor surfaces before rotor machining or reassembly ensures that dirt and
corrosion will not add lateral runout to the rotor. Proper cleaning of the hub flange will also minimize
the stack-up of lateral runout. On reassembly, the rotor should be reinstalled aligning the marks
made on disassembly.
Always use a torque wrench or the appropriate Torque Socket found in J 39544-KIT on an impact
wrench when installing the wheel and tire assembly. Torque all wheel nuts using the correct
sequence and torque. Refer to the Tire and Wheel Sub-Section in the applicable Service Manual.
Excessive torque or torque variation between wheel nuts may cause distortion of the hub and rotor
mating surface. This distortion may cause lateral runout and lead to brake pulsation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6859
Technical Service Bulletin # 23-50-05B Date: 971101
Brakes - Rotor Warranty Service Procedure
File In Section: 5 - Brakes
Bulletin No.: 23-50-05B
Date: November, 1997
INFORMATION
Subject: Brake Rotor Warranty Service Procedure
Model: 1994-98 GM Passenger Cars
This bulletin outlines GM's procedures for brake rotor service for all applicable GM passenger cars
and supersedes Corporate Bulletin Number 23-50-05A Section 5 - Brakes).
Important:
Rotors should only be turned when one or more of the following rotor surface conditions exist:
1. Severe Scoring - depth in excess of 1.5 mm (0.060 in.). 2. Pulsation Concerns from:
a. Thickness variation in excess of 0.025 mm (0.001 in.). b. Corrosion on rotor braking surfaces.
Rotors are NOT to be resurfaced in an attempt to correct:
1. Noise/squeal. 2. Cosmetic corrosion. 3. Routine pad replacement. 4. Discoloration and/or "hard
spots".
Explanation of Brake Rotor Warranty Service Procedure
Research and testing has determined:
1. Rotor refacing during normal pad replacement is not necessary.
2. Rotor refacing for cosmetic corrosion is unnecessary. Clean-up of braking surfaces can be
accomplished by 10-15 moderate stops from 62-75 km/h (35-40 mph) with cooling time between
stops.
3. Rotor service is ineffective in correcting BRAKE SQUEAL, and/or PREMATURE LINING WEAR
OUT, and should NOT be used to address these conditions.
4. When installing new rotors, DO NOT reface them.
5. Ensure bearing flanges are free of corrosion when installing rotors to prevent inducing lateral
runout. Use Kent Moore tool J 42450 to clean the corrosion around the wheel studs.
Brake Service Techniques
EVERY brake service should include:
1. Clean and lube all metal-to-metal contact points (i.e.; caliper to knuckle, pad to knuckle, etc.).
2. Clean and lube slide pins.
3. Set correct clearances - caliper to knuckle, etc.
4. Clean rotor and hub mounting surfaces. Use Kent Moore tool J 42450 to clean around wheel
studs.
Pulsation
Brake pulsation concerns may result from two basic conditions:
1. Thickness variation.
2. Excessive corrosion.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6860
Rotor thickness variation is the result of uneven rotor wear caused by excessive lateral runout
(>0.076 mm; >0.003 in.). Lateral runout can be induced by:
1. Distortion of the braking surface by applying uneven and/or excessive wheel nut torque.
(This could be the result of a recent tire change, rotation, etc.).
2. Improperly refacing rotors.
Brake Noise
Important:
SOME BRAKE NOISE IS NORMAL.
Brake noise is caused by a "slip stick" type vibration of brake components. Some intermittent brake
noise may be normal. Performing 3-4 aggressive stops may temporarily reduce or eliminate most
brake squeal. If the noise persists, a brake dampening compound may be applied to the back of
each pad. Use Permatex Disc Brake Quiet # 126HB or equivalent. Also, clean and lube all
metal-to-metal contact areas between pads, pad guides, caliper and knuckles with a thin layer of
high temperature silicone grease. This allows parts to slide freely and not vibrate when moving
relative to each other.
Rotor Grooving
Excessive grooving can be caused by foreign material in contact with the rotor, but most often rotor
grooving is the result of normal brake wear. DO NOT RESURFACE ROTORS FOR LIGHT
GROOVING. Resurface rotors only when grooves of 1.5 mm (0.060 in.) or deeper are present.
A dime may be used to determine disc brake groove depth. Place a dime in the groove, with
Roosevelt's head toward the groove. If the dime goes into the groove beyond the top of his head,
the groove exceeds 1.5 mm (0.060 in.) and the rotor should be serviced. (In Canada, if any portion
of the letters of "In Canada" are covered, the rotor should serviced.)
It the groove is too narrow for the dime to be inserted, it is not a cause for concern.
High Pedal Effort
Follow Service Manual diagnostic procedures for this condition. Service rotors if they have been
recently resurfaced. (The surface finish may be out-of-specification).
Lightly Rusted Rotors
Light surface rust on rotor braking surfaces is often cosmetic and can be eliminated during a few
normal driving stops. Rusting may occur when a vehicle is not driven for extended periods. Rotors
with surface rust on unsold new cars can usually be burnished clean by performing 15 moderate
stops from 62-75 km/h (35-40 mph) with cooling time between stops.
Facts About Brake Service
^ Original equipment rotor surfaces are ground to ensure smooth finish and parallelism between
mounting and friction surfaces. New rotors should not be resurfaced before installation.
^ Improper tightening of wheel nuts can induce lateral runout (distortion of braking surfaces) which
will lead to uneven wear. As high spots are worn down, resulting thickness variation will cause
brake pulsation.
^ Ensure wheel bearing flange is clean and free of corrosion before installing new rotors. A new
essential tool (Kent Moore tool J 42450) will soon be sent to all dealers. This tool makes it easier to
clean corrosion around the wheel studs.
^ Always mark the position of rotor on the hub before removal, and reinstall the rotor in the same
position.
^ Rotors with perceived hard spots or discoloration should not be serviced. These conditions are
normal.
^ Installation of new rotors does not require pad replacement. Do NOT replace pads unless their
condition requires it.
^ It is NOT necessary to replace rotors in pairs. Rotors may be serviced individually.
^ A TORQUE LIMITING SOCKET OR TORQUE WRENCH MUST BE USED to insure that the
wheel nuts are tightened to specification. This should be done in 3 steps using the star pattern.
1. Snug the nuts down by hand. 2. Using the star pattern and a torque limiting socket or torque
wrench, tighten the wheel nuts to about half the final torque. 3. Tighten the wheel nuts to
specification using the star pattern and a torque limiting socket or torque wrench.
^ NEVER use lubricants or penetrating fluids on wheel studs, nuts, or mounting surfaces. Wheel
nuts, studs, and mounting surfaces must be clean and dry.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Brakes - Rotor Lateral Runout Correction Information > Page 6861
Brake Rotor/Disc: Technical Service Bulletins Brakes - Revised Rear Rotor Specifications
File In Section: 5 - Brakes
Bulletin No.: 73-50-12
Date: April, 1997
SERVICE MANUAL UPDATE
Subject: Section 5B2 - Revised Rear Disc Brake Rotor Specifications
Models: 1994-96 Chevrolet Caprice, Impala SS
This bulletin is being issued to revise the rear disc brake rotor specifications listed in Section 5B2 of
the Service Manual. The correct specifications for the rotor are:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Technical Service Bulletins > Page 6862
Brake Rotor/Disc: Specifications
Nominal Thickness 1.043 in
Minimum Refinish Thickness 0.965 in
Thickness Variation (Parallelism) 0.0005 in
Lateral Runout (T.I.R.) 0.003 in
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Service and Repair > Front Disc Brakes
Brake Rotor/Disc: Service and Repair Front Disc Brakes
1. Remove caliper assembly from steering knuckle as described in Brake
Caliper/Removal/Installation. 2. On models with anti-lock brakes, proceed as follows:
a. Remove wheel speed sensor retaining bolt from rear side of steering knuckle. b. Remove wheel
speed sensor from steering knuckle and position aside.
3. On all models, remove wheel bearing lubricant cap from center of rotor. 4. Remove cotter pin,
nut and washer from steering knuckle assembly. 5. Carefully pull brake rotor from steering knuckle.
6. Reverse procedure to install, prior to installing cotter pin onto steering knuckle, adjust wheel
bearing as follows:
a. Torque nut to 21 ft. lbs. while turning brake rotor clockwise. This will remove any grease or burrs
which may cause excessive wheel bearing
play.
b. Back off nut to a just loose position. c. Hand tighten nut until next slot. d. Install cotter pin and
wheel bearing lubricant cap.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Disc Brake System > Brake Rotor/Disc > Component
Information > Service and Repair > Front Disc Brakes > Page 6865
Brake Rotor/Disc: Service and Repair Rear Disc Brakes
1. Remove caliper as described in Brake Caliper/Removal/Installation. 2. Remove caliper mounting
bracket attaching bolts, then the mounting bracket. 3. Remove rotor from hub and bearing
assembly. 4. Reverse procedure to install, adjust parking. brake as described under Adjustments.
Refer to Parking Brake System.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Drum Brake System > Wheel Cylinder > Component
Information > Technical Service Bulletins > Brakes - Wheel Cylinder Inspection Guidelines
Wheel Cylinder: Technical Service Bulletins Brakes - Wheel Cylinder Inspection Guidelines
Bulletin No.: 03-05-24-001A
Date: March 21, 2005
INFORMATION
Subject: Service Information Regarding Rear Brake Drum Wheel Cylinder Inspections
Models: 2005 and Prior GM Passenger Cars and Trucks 2005 and Prior Saturn Vehicles
with Rear Drum Brakes
Supercede:
This bulletin is being revised add model years and include all GM vehicles. Please discard
Corporate Bulletin Number 03-05-24-001 (Section 03 - Suspension).
This bulletin provides information on proper inspection of rear drum brake wheel cylinders.
Important:
It is not recommended that dust boots be removed during inspection processes as dirt and debris
could contaminate the wheel cylinder bore causing premature wear of the wheel cylinder. In
addition, most bores should look damp and some lubricant may drip out from under the boot as a
result of lubricant being present.
All rear drum brake wheel cylinders are assembled with a lubricant to aid in assembly, provide an
anti-corrosion coating to the cylinder bore, and lubricate internal rubber components. As a result of
this lubrication process, it is not uncommon for some amount of lubricant to accumulate at the ends
of the cylinder under the dust boot.
Over time, the lubricant may work its way to the outside of the boot and cause an area of the boot
to look damp. Evidence of a damp area on the boot does not indicate a leak in the cylinder.
However, if there is excessive wetness (i.e. drips) coming from the boot area of the wheel cylinder,
it could indicate a brake hydraulic fluid leak requiring wheel cylinder replacement. (Refer to the
Wheel Cylinder Replacement procedures in the appropriate Service Manual.)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Drum Brake System > Wheel Cylinder > Component
Information > Technical Service Bulletins > Page 6871
Wheel Cylinder: Specifications
Wheel Cylinder Bore Diameter 1 in
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Drum Brake System > Wheel Cylinder > Component
Information > Technical Service Bulletins > Page 6872
Wheel Cylinder: Service and Repair
Fig. 33 Exploded View Of Wheel Cylinder
1. Raise and support vehicle.
2. Remove wheel, drum and brake shoes.
3. Disconnect hydraulic line at wheel cylinder. Do not pull metal line away from cylinder, as this
may kink or bend line. Line will separate from cylinder when cylinder is moved away from brake
backing plate.
4. Remove wheel cylinder-to-brake plate attaching screws, then the wheel cylinder.
5. Remove boots, pistons, springs and cups from cylinder, Fig. 33.
6. Clean all parts with brake fluid.
7. Inspect cylinder bore. A scored bore may be honed as long as the diameter is not increased by
more than .005 inch. Replace worn or damaged parts as necessary.
8. Ensure hands are clean before proceeding with assembly. Lubricate cylinder wall and rubber
cups with brake fluid, then install springs, cups, pistons and boots in housing.
9. Wipe end of hydraulic line to remove any foreign matter, then place wheel cylinder in position.
Enter tubing into cylinder and start threads on fitting.
10. Secure cylinder to backing plate, then complete tightening of tubing fitting.
11. Install brake shoes, drum and wheel.
12. Bleed system as outlined previously, then adjust brakes.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Bleeding > System
Information > Service and Repair > With ABS System
Brake Bleeding: Service and Repair With ABS System
Manual Bleeding
Fig. 210 Brake System Manual Bleed.
NOTE: Pressure bleeding is recommended for all hydraulic systems. However, if a pressure
bleeder is unavailable, use the following procedure.
CAUTION: Brake fluid damages painted surfaces. Immediately clean any spilled fluid.
1. Remove vacuum reserve by pumping brakes several times with engine off. 2. Fill master cylinder
reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let
reservoir fall below half full. 3. If necessary, bleed master cylinder as follows:
a. Disconnect master cylinder forward brake line connection until fluid flows from reservoir.
Reconnect and tighten brake line. b. Instruct an assistant to slowly depress brake pedal one time
and hold. c. Crack open front brake line connection again, purging air from cylinder. d. Retighten
connection and slowly release brake pedal. e. Wait 15 seconds, then repeat until all air is purged. f.
Bleed the rearward (nearest the cowl) brake line connection by repeating preceding steps.
4. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 5. Proceed to appropriate wheel first and follow set sequence according
to Wheel Bleed Sequence. See: Wheel Bleed Sequence 6. Place transparent tube over bleeder
valve, then allow tube to hang down into transparent container, Fig. 210. Ensure end of tube is
submerged in
clean brake fluid.
7. Instruct an assistant to slowly depress brake pedal one time and hold. 8. Crack open bleeder
valve, purging air from cylinder. Retighten bleeder screw and slowly release pedal. 9. Wait 15
seconds, then repeat preceding bleed steps. Repeat these steps until all air is bled from system.
Pressure Bleeding
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Bleeding > System
Information > Service and Repair > With ABS System > Page 6878
Fig. 210 Brake System Manual Bleed.
Fig. 21 Installing Pressure Bleeder Adapter
1. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 2. Using a diaphragm type pressure bleeder, install suitable bleeder
adapter to master cylinder, Fig. 211. 3. Charge bleeder ball to 20-25 psi. 4. Connect pressure
bleeder line to adapter. 5. Open line valve on pressure bleeder, then depress bleed-off valve on
adapter until a small amount of brake fluid is released. 6. Raise and support vehicle. 7. Proceed to
appropriate wheel first and follow set sequence according to Wheel Bleeding Sequence. See:
Wheel Bleed Sequence 8. Place transparent tube over bleeder valve, then allow tube to hang down
into transparent container, Fig. 210. Ensure end of tube is submerged in
clean brake fluid.
9. Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from
line.
Wheel Bleed Sequence
If manual bleeding, RR-LR-RF-LF; if pressure bleeding, bleed front brakes together and rear
brakes together.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Bleeding > System
Information > Service and Repair > With ABS System > Page 6879
Brake Bleeding: Service and Repair Without ABS System
Manual
Fig. 210 Brake System Manual Bleed.
NOTE: Pressure bleeding is recommended for all hydraulic systems. However, if a pressure
bleeder is unavailable, use the following procedure. Brake fluid damages painted surfaces.
Immediately clean any spilled fluid.
1. Remove vacuum reserve by pumping brakes several times with engine off. 2. Fill master cylinder
reservoir with clean brake fluid. Check fluid level often during bleeding procedure; do not let
reservoir fall below half full. 3. If necessary, bleed master cylinder as follows:
a. Disconnect master cylinder forward brake line connection until fluid flows from reservoir.
Reconnect and tighten brake line. b. Instruct an assistant to slowly depress brake pedal one time
and hold. c. Crack open front brake line connection again, purging air from cylinder. d. Retighten
connection and slowly release brake pedal. e. Wait 15 seconds, then repeat until all air is purged. f.
Bleed the rearward (nearest the cowl) brake line connection by repeating steps a through e.
4. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 5. Proceed to appropriate wheel first and follow set sequence according
to Wheel Bleeding Sequence. 6. Place transparent tube over bleeder valve, then allow tube to
hang down into transparent container, Fig. 16. Ensure end of tube is submerged in
clean brake fluid.
7. Instruct an assistant to slowly depress brake pedal one time and hold. 8. Crack open bleeder
valve, purging air from cylinder. Retighten bleeder screw and slowly release pedal. 9. Wait 15
seconds, then repeat steps 7 and 8. Repeat these steps until all air is bled from system.
Pressure
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Bleeding > System
Information > Service and Repair > With ABS System > Page 6880
Fig. 21 Installing Pressure Bleeder Adapter
Fig. 210 Brake System Manual Bleed.
1. Loosen, then slightly retighten bleeder valves at all four wheels. Repair any broken, stripped or
frozen valves at this time. 2. Using a diaphragm type pressure bleeder, install suitable bleeder
adapter to master cylinder, Fig. 17. 3. Charge bleeder ball to 20-25 psi. 4. Connect pressure
bleeder line to adapter. 5. Open line valve on pressure bleeder, then depress bleed-off valve on
adapter until a small amount of brake fluid is released. 6. Raise and support vehicle. 7. Proceed to
appropriate wheel first and follow set sequence according to Wheel Bleeding Sequence. 8. Place
transparent tube over bleeder valve, then allow tube to hang down into transparent container, Fig.
16. Ensure end of tube is submerged in
clean brake fluid.
9. Open bleeder valve 1/2 to 3/4 turn and allow fluid to flow into container until all air is purged from
line.
Front Disc Brakes
NOTE: Pressure bleeding is recommended for all hydraulic disc brake systems.
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. On
vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid
level in master cylinder during bleeding operation.
Never use brake fluid that has been drained from hydraulic system when bleeding the brakes. Be
sure the disc brake pistons are returned to their normal positions and that the shoe and lining
assemblies are properly seated. Before driving the vehicle, check brake operation to be sure that a
firm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Bleeding > System
Information > Service and Repair > With ABS System > Page 6881
pedal has been obtained.
Rear Disc Brakes
NOTE: Pressure bleeding is recommended for all hydraulic disc brake systems.
The disc brake hydraulic system can be bled manually or with pressure bleeding equipment. On
vehicles with disc brakes the brake pedal will require more pumping and frequent checking of fluid
level in master cylinder during bleeding operation.
Never use brake fluid that has been drained from hydraulic system when bleeding the brakes. Be
sure the disc brake pistons are returned to their normal positions and that the shoe and lining
assemblies are properly seated. Before driving the vehicle, check brake operation to be sure that a
firm pedal has been obtained.
Wheel Bleeding Sequence
Rear wheel drive models: if manual bleeding, RR-LR-RF-LF; if pressure bleeding, bleed front
brakes together and rear brakes together. Front wheel drive models: RR-LF-LR-RF
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Specifications > Bore Diameter
Brake Caliper: Specifications Bore Diameter
Caliper Bore Diameter 2.94 in
Caliper Bore Diameter 2.126 in
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Specifications > Bore Diameter > Page 6886
Brake Caliper: Specifications Tightening Specifications
Brake Hose To Caliper 30 ft.lb
Caliper Bleeder Screw 7 ft.lb
Front Caliper Mounting Bracket 166 ft.lb
Rear Bracket Mounting Bolt 70 ft.lb
Rear Lower Guide Pin Bolt 16 ft.lb
Rear Pivot Pin Nut 16 ft.lb
Rear Upper Guide Pin Bolt 26 ft.lb
Brake Hose To Caliper 33 ft.lb
Caliper Bleeder Screw 115 ft.lb
Caliper Mounting Bolts 38 ft.lb
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes
Brake Caliper: Service and Repair Front Disc Brakes
Removal/Installation
Fig. 3 Piston Compressing W/C-Clamp
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6889
Fig. 4 Caliper & Mounting Bolts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6890
Fig. 8 Caliper & Stops Clearance Inspection
REMOVAL
1. Siphon enough brake fluid out of master cylinder to bring fluid level to 1/3 full to avoid fluid
overflow when caliper piston is pushed back into its
bore.
2. Raise vehicle and remove front wheels. 3. Using a C-clamp, as illustrated in Fig. 3, push piston
back into its bore. 4. If caliper assembly is to be serviced, remove inlet fitting attaching bolt, copper
washer, and inlet fitting from caliper housing. Plug opening in inlet
fitting to prevent fluid loss and contamination. Do not crimp brake hose, as this may damage
internal structure of hose. If only shoe and lining assemblies are to be replaced, do not disconnect
brake line fitting from caliper.
5. Remove two mounting bolts, Fig. 4, and lift caliper away from disc. If only shoe and lining
assemblies are to be replaced, suspend caliper from
chassis using suitable hanger. Do not allow caliper to hang by brake hose.
INSTALLATION
1. Position caliper over disc, lining up holes in caliper with holes in mounting bracket. If brake hose
was not disconnected during removal, be sure
not to kink it during installation.
2. Start mounting bolts through sleeves in inboard caliper ears and mounting bracket, making sure
ends of bolts pass under ears on inboard shoe.
Right and left calipers must not be interchanged.
3. Push mounting bolts through to engage holes in outboard ears. Then thread mounting bolts into
bracket. 4. Tighten mounting bolts to specifications. 5. Check dimensions between each caliper
stop and caliper, Fig. 8. 6. If brake hose was removed, reconnect it and bleed calipers. 7. Replace
front wheels, lower vehicle and add brake fluid to master cylinder to bring level to 1/4 inch from top.
Before moving vehicle, pump
brake pedal several times to be sure it is firm. Do not move vehicle until a firm pedal is obtained.
On some models with low drag calipers, apply approximately 175 pounds of pressure to brake
pedal three times to properly seat caliper and related components.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6891
Disassemble/Assemble
Fig. 5 Caliper Piston Removal.
Fig. 6 Boot To Piston Installation.
Fig. 7 Boot To Caliper Piston
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6892
DISASSEMBLE
1. Remove caliper. Refer to Removal/Installation. 2. Clean outside of caliper, then drain brake fluid
from caliper. 3. Use clean shop towels to pad interior of caliper assembly, then remove piston by
directing compressed air into caliper brake hose inlet hole, Fig. 5.
Use just enough air pressure to ease piston out of bore. Do not place fingers in front of piston for
any reason when applying compressed air. This could result in serious personal injury.
4. Carefully pry dust boot out of bore. 5. Using a small piece of wood or plastic, remove piston seal
from bore. Do not use a metal tool of any kind to remove seal as it may damage
bore.
6. Remove bleeder valve. 7. Inspect piston for scoring, nicks, corrosion, and wear and replace as
needed. 8. Inspect caliper housing and seal groove for corrosion, nicks, scoring and excessive
wear, and use crocus cloth to polish away corrosion from
housing bore. Replace caliper housing if corrosion in and around seal groove will not clean up with
crocus cloth.
9. Clean all parts with denatured alcohol. Dry with unlubricated compressed air. Blow out all
passages in housing and bleeder valve.
ASSEMBLE
1. Lubricate caliper piston bore and new piston seal with clean brake fluid. Position seal in bore
groove. Ensure seal is not twisted. 2. Lubricate piston with clean brake fluid and assemble a new
boot into groove in piston so the fold faces the open end of piston, Fig. 6. 3. Using care not to
unseat seal, insert piston into bore and force piston to the bottom of bore. 4. Position dust boot in
caliper counterbore and install, using suitable seal installer, Fig. 7. Check boot installation to be
sure retaining ring
molded into boot is not bent and that boot is installed below caliper face and evenly all around. If
boot is not fully installed, dirt and moisture may enter bore and cause corrosion.
5. Install brake hose in caliper using a new copper gasket. 6. Install shoes and reinstall caliper
assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6893
Brake Caliper: Service and Repair Rear Disc Brakes
Removal/Installation
Fig. 3 Disabling Parking Brake Automatic Adjuster Mechanism
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6894
Fig. 1 Exploded View Of PBR Single Piston Rear Caliper
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6895
Fig. 4 Parking Brake Free Travel Adjustment
REMOVAL
1. Disable parking brake automatic adjuster as follows:
a. Working from inside vehicle, remove driver seat cushion, then the parking brake lever cover
screws and cover. b. Using 0.080 inch gauge wire, fabricate a tool to disengage drive pawl from
sector, Fig. 3. c. Using tool mentioned above, disengage drive pawl from sector, then insert a nail
through anchor plate to keep drive pawl in disengaged
position.
d. Pull up on lever until it aligns with pawl, then depress button until lever is fully downward. e.
Visually inspect that anchor plate is fully against stud. If not, repeat procedure as needed. f.
Pull front parking brake cable rearward to slacken cable at caliper assembly.
2. Raise and support vehicle, then remove tire and wheel assembly. 3. Install two wheel retaining
nuts to retain rotor in position. 4. If caliper requires overhaul, remove inlet fitting attaching bolt, then
disconnect inlet fitting from caliper housing. Discard the two gaskets, then
plug openings in inlet fitting and caliper to prevent loss or contamination of fluid.
5. Remove caliper lever return spring. Discard spring if coils are open. 6. Disconnect parking brake
cable from lever (5) and caliper bracket (8), Fig. 1. 7. Remove upper and lower guide pin bolts,
then remove caliper from rotor and mounting bracket. If caliper does not require overhaul, suspend
it
from suspension to prevent damage to brake line.
INSTALLATION
1. Install shoe and lining assemblies, if removed, as outlined previously. 2. Position caliper over
rotor and onto mounting bracket, then install upper and lower guide pin bolts. Torque upper bolt to
26 ft. lbs. and lower bolt
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6896
to 16 ft. lbs.
3. Attach parking brake cable to caliper bracket and lever, then install lever return spring. 4. If
removed, install inlet fitting using new gaskets, then bleed brake system. 5. If caliper was
overhauled, adjust parking brake free travel as follows:
a. Have an assistant apply a light load to brake pedal until rotor can no longer be turned by hand.
b. Apply pressure to caliper lever in direction shown in Fig. 4. c. Measure free travel between
caliper lever and housing. Free travel should be 0.024-0.028 inch. If free travel is not as specified,
proceed to next
step.
d. Remove adjustment screw, then clean thread adhesive from threads. e. Coat threads with new
adhesive, reinstall adjustment screw, then turn as required until specified free travel is obtained.
Turning screw
clockwise increases free travel, while counterclockwise rotation decreases travel.
f. Release brake pedal, then firmly apply brake pedal three times and recheck free travel. Repeat
adjustment procedure as necessary.
6. Remove nail from anchor plate installed during caliper removal procedure. 7. Apply and release
parking brake three times, then lift lever upward and ensure parking brake fully engages at 7-9
clicks. 8. Release parking brake. No brake drag should exist and no gap between caliper housings
and parking levers should be evident. 9. Install parking brake lever cover, screws and driver's
cushion.
10. Reinstall tire and wheel assembly, then check and refill master cylinder as required. 11. Start
engine and pump brake pedal several times to seat brake linings.
Disassemble/Assemble
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6897
Fig. 1 Exploded View Of PBR Single Piston Rear Caliper
DISASSEMBLE
1. Remove caliper. Refer to Removal/Installation. 2. Remove the two return springs from actuating
collar, then pull collar out of caliper housing and remove clamp rod (28) and bushing (27), Fig. 1.
discard bushing.
3. Bend back boot retainer tabs, then remove retainers (21, 31), boots (20, 25) and pushrod (22)
from actuating collar. Remove preload spring (23)
from retainer (31), then discard retainers and boots.
4. Use clean shop towels to pad interior of caliper assembly, then remove piston by directing
compressed air into caliper brake hose inlet hole, Use
just enough air pressure to ease piston out of bore. Do not place fingers in front of piston for any
reason when applying compressed air. This could result in serious personal injury.
5. Using a small piece of wood or plastic, remove piston seal from bore. Do not use a metal tool of
any kind to remove seal as it may damage
bore.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Caliper > Component
Information > Service and Repair > Front Disc Brakes > Page 6898
6. Remove bleeder valve cap and bleeder valve. 7. Remove seal (1), sprag clip (2) and lever (5)
from pivot pin (3). Discard sprag clip. 8. Clean all metal components with suitable solvent, then dry
with compressed air. 9. Inspect parking brake lever components, piston, caliper bore and mounting
bracket for scoring, excessive wear or corrosion. Replace parts as
necessary.
CALIPER ASSEMBLE
1. Using clean brake fluid, lubricate piston seal, then install seal into caliper bore groove. Ensure
seal is not twisted during installation. 2. Using clean brake fluid, lubricate caliper bore and piston. 3.
Place piston into caliper bore, then push downward until fully bottomed in bore. 4. Apply lubricant
provided in repair kit to actuating collar (24), then install pushrod (22), new boots (20, 25) and new
retainers (21, 31) onto collar,
Fig. 1. Clamp retainers firmly against collar, then bend tabs on retainer (21) to hold assembly
together.
5. Reconnect preload spring (23) onto retainer (31). 6. Apply lubricant provided in repair kit to
clamp rod (28), then slide rod through holes in boot (25) and actuating collar (24). Ensure boot is
firmly
positioned against reaction plate on clamp rod.
7. Lubricate new compliance bushing (27), then install bushing onto clamp rod (28). 8. Lubricate
grooved bead of inner boot (20), boot groove in caliper housing and actuating collar with lubricant
provided in repair kit. 9. Push clamp rod to bottom of piston mating hole, then pull actuating collar
(24) and seat inner boot (20) into boot groove in caliper housing.
10. Ensure pushrod (22) is positioned in hole in caliper housing, then install bleeder cap and valve.
11. If removed, install pivot pin (3) and new nut (12) onto caliper, torque nut to 16 ft. lbs., then
lubricate parking brake lever (5) and pivot pin. 12. Install pivot pin seal (1), parking brake lever and
new sprag clip (2), ensuring teeth of sprag clip face away from lever, then snap seal cap over
pivot pin.
13. Install the two collar return springs (26) onto retainer (31). Ensure retainer enters springs at end
of second coil. 14. Install adjustment screw (11) into caliper housing until actuating collar is parallel
to piston bore face of housing. 15. Lubricate guide pins with suitable grease, then slide boots onto
pins. 16. Fill boots with grease, then install into mounting bracket. Ensure boots are properly
positioned in grooves in pins and mounting bracket. 17. Install caliper and bleed brake system,
then adjust parking brake free travel under Adjustments. Refer to Parking Brake System.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Fluid > Component
Information > Technical Service Bulletins > Brake Fluid - Level & Filling Recommendations
Brake Fluid: Technical Service Bulletins Brake Fluid - Level & Filling Recommendations
File In Section: 05 - Brakes
Bulletin No.: 00-05-22-004
Date: May, 2000
INFORMATION
Subject: Brake Fluid Level and Filling Recommendations
Models: 2001 and Prior Passenger Cars and Trucks
Many dealers and after-market repair shops advertise multi-point fluid "top-ups" in conjunction with
oil changes or regular maintenance packages. These offers often include adding brake fluid to the
master cylinder reservoir. There are only two reasons why the brake fluid level in the brake
reservoir might go down. The first is that the brake fluid level goes down an acceptable level during
normal brake lining wear. When the linings are replaced, the fluid will return to it's original level.
The second possible reason for a low fluid level is that fluid is leaking out of the brake system. If
fluid is leaking, the brake system requires repair and adding additional fluid will not correct the leak.
If the system was properly filled during delivery of the vehicle, no additional fluid should be required
under most circumstances between brake pad and/or shoe replacements. This information can be
reinforced with the customer by referring them to the Brake Fluid section of their vehicle's Owner's
Manual.
Guidelines
GM vehicles have incorporated a variety of brake fluid reservoir styles. The following guidelines are
restricted to the plastic bodied fluid reservoirs and do not affect the original service
recommendations for the older style metal bodied units.
You may encounter both black plastic and translucent style reservoirs. You may have reservoirs
with:
^ A MAX fill mark only
^ A MIN fill mark only
^ Both MAX and MIN marks
The translucent style reservoirs do not have to have the covers removed in order to view the fluid
level. It is a good practice not to remove the reservoir cover unless necessary to reduce the
possibility of contaminating the system. Use the following guidelines to assist in determining the
proper fluid level.
Important:
When adding brake fluid, use Delco Supreme II(R) Brake Fluid, GM P/N 12377967 or equivalent
brand bearing the DOT-3 rating only.
Important:
At no time should the fluid level be allowed to remain in an overfilled condition. Overfilling the brake
reservoir may put unnecessary stress on the seals and cover of the reservoir. Use the following
guidelines to properly maintain the fluid level. If the reservoir is overfilled, siphon out the additional
fluid to comply with the guidelines below.
Important:
If under any circumstance the brake fluid level is extremely low in the reservoir or the BRAKE
warning indicator is illuminated, the brake system should be checked for leaks and the system
repaired in addition to bringing the fluid level up to the recommended guidelines outlined below. A
leaking brake system will have reduced braking performance and will eventually not work at all.
Important:
Some vehicles have reservoirs that are very sensitive to brake fluid levels and may cause the
BRAKE indicator to flicker on turns as the fluid approaches the minimum required level. If you
encounter a vehicle with this concern, increase the fluid level staying within the guidelines outlined
below.
^ If the reservoir has a MAX level indicator, the reservoir should be returned to the MAX marking
only at the time new brake pads and/or shoes are installed. If the reservoir fluid level is at the
half-way point or above do not attempt to add additional brake fluid during routine fluid checks.
^ If the reservoir has both MAX and MIN indicators, the fluid level should be maintained above the
MIN indicator during routine fluid checks and returned to the MAX indication only after new brake
pads and/or shoes are installed.
^ For reservoirs with only a MIN indication, the fluid level should be maintained above the MIN
indicator during routine fluid checks. Return the
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Information > Technical Service Bulletins > Brake Fluid - Level & Filling Recommendations > Page 6903
reservoir fluid level to full only after installing new brake pads and/or shoes. A full reservoir is
indicated on translucent, snap cover reservoirs by a fluid level even with the top level of the view
window imprinted into the side of the reservoir. On screw top models in black or translucent plastic,
the full level is just below the bottom of the filler neck.
Parts Information
Part Number Description
12377967 Brake Fluid
Parts are currently available from GMSPO.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Fluid > Component
Information > Technical Service Bulletins > Page 6904
Brake Fluid: Specifications
Brake System DOT 3
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Fluid Level Sensor/Switch
> Component Information > Description and Operation
Brake Fluid Level Sensor/Switch: Description and Operation
OPERATION
This sensor mounted on the master cylinder will activate the Brake Warning lamp if a low brake
fluid level is detected. The lamp will turn off once the fluid level is corrected.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Fluid Pressure
Sensor/Switch > Component Information > Locations
LH Rear Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Fluid Pressure
Sensor/Switch > Component Information > Locations > Page 6911
Brake Fluid Pressure Sensor/Switch: Description and Operation
Fig. 3 Pressure Differential Valve & Brake Warning Lamp Switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Fluid Pressure
Sensor/Switch > Component Information > Locations > Page 6912
Fig. 4 Dual Master Cylinder W/Built In Warning Lamp Switch.
DESCRIPTION
In Fig. 3, as pressure falls in one system, the other system's normal pressure forces the piston to
the inoperative side, contacting the switch terminal, causing the warning lamp on the instrument
panel to glow.
In Fig. 4 shows the switch mounted directly in the master cylinder assembly. Whenever there is a
specified differential pressure, the switch piston will activate the brake failure warning switch and
cause the brake warning lamp to glow.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake
Proportioning/Combination Valve > Component Information > Description and Operation > Brake Distribution Valve & Switch
Brake Proportioning/Combination Valve: Description and Operation Brake Distribution Valve &
Switch
Fig. 12 Distribution Switch. Diagonally Split Brake System
Fig. 16 Brake Distribution Switch. Normal
Fig. 16 Brake Distribution Switch. Normal
DESCRIPTION
This switch assembly, Fig. 12. is used on some diagonally split brake systems and Corvette four
wheel disc brake systems. It is connected to the outlet ports of the master cylinder and to the brake
warning lamp and warns the driver if either the primary or secondary brake system has failed.
OPERATION
When hydraulic pressure is equal in both primary and secondary brake systems, the switch
remains centered, Fig. 13. If pressure fails in one of the systems, the piston moves toward the
inoperative side, Fig. 14. The shoulder of the piston contacts the switch terminal, providing a
ground and lighting the warning lamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake
Proportioning/Combination Valve > Component Information > Description and Operation > Brake Distribution Valve & Switch
> Page 6917
Brake Proportioning/Combination Valve: Description and Operation Combination Valve
Combination Valve
Fig. 5 Combination Valve
DESCRIPTION
The combination valve, Fig. 5 is a metering valve, failure warning switch, and a proportioner in one
assembly and is used on disc brake applications.
OPERATION
The metering valve delays front disc braking until the rear drum brake shoes contact the drum. The
failure warning switch is actuated in event of front or rear brake system failure, in turn activating a
dash warning lamp. The proportioner balances front to rear braking action during rapid
deceleration.
Metering Valve
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake
Proportioning/Combination Valve > Component Information > Description and Operation > Brake Distribution Valve & Switch
> Page 6918
Fig. 6 Metering Valve. Initial Braking
Fig. 7 Metering Valve. Continued Braking
DESCRIPTION
When the brakes are not applied, the metering valve permits the brake fluid to flow through the
valve, thus allowing the fluid to expand and contract with temperature changes.
OPERATION
When the brakes are initially applied, the metering valve stem moves to the left, preventing fluid to
flow through the valve to the front disc brakes. This is accomplished by the smooth end of the
metering valve stem contacting the metering valve seal lip at 4 to 30 psi, Fig. 6. The metering valve
spring holds the retainer against the seal until a predetermined pressure is produced at the valve
inlet port which overcomes the spring pressure and permits hydraulic pressure to actuate the front
disc brakes, Fig. 7. The increased pressure into the valve is metered through the valve seal, to the
front disc brakes, producing an increased force on the diaphragm. The diaphragm then pulls the
pin, in turn pulling the retainer and reduces the spring pressure on the metering valve seal.
Eventually, the pressure reaches a point at which the spring is pulled away by the diaphragm pin
and retainer, leaving the metering valve unrestricted, permitting full pressure to pass through the
metering valve.
Failure Warning Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake
Proportioning/Combination Valve > Component Information > Description and Operation > Brake Distribution Valve & Switch
> Page 6919
Fig. 8 Failure Warning Switch. Rear System Failure
DESCRIPTION
If the rear brake system fails, the front system pressure forces the switch piston to the right, Fig. 8.
The switch pin is then forced up into the switch, completing the electrical circuit and activates the
dash warning lamp.
OPERATION
When repairs are made and pressure returns to the system, the piston moves to the left, resetting
the switch. The detent on the piston requires approximately 100 to 450 psi to permit full reset of the
piston. In event of front brake system failure, the piston moves to the left and the same sequence
of events is followed as for rear system failure except the piston resets to the right.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake
Proportioning/Combination Valve > Component Information > Description and Operation > Brake Distribution Valve & Switch
> Page 6920
Brake Proportioning/Combination Valve: Description and Operation Proportioning Valve
Fig. 9 Proportioner. Rapid Deceleration
Fig. 9 Proportioner. Rapid Deceleration
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake
Proportioning/Combination Valve > Component Information > Description and Operation > Brake Distribution Valve & Switch
> Page 6921
Fig. 11 Proportioners Installed In Master Cylinder
During rapid deceleration, a portion of vehicle weight is transferred to the front wheels. This
resultant loss of weight at rear wheels must be compensated for to avoid early rear wheel skid. The
proportioner or pressure control valve reduces rear brake system pressure, delaying rear wheel
skid. When the proportioner or pressure control valve is incorporated in the combination valve
assembly, pressure developed within the valve acts against the large end of the piston, overcoming
the spring pressure, moving the piston left, Fig. 9. The piston then contacts the stem seat and
restricts line pressure through the valve.
During normal braking operation, the proportioner or pressure control valve is not functional. Brake
fluid flows into the proportioner or pressure control valve between the piston center hole and the
valve stem, through the stop plate and to the rear brakes. Spring pressure loads the piston during
normal braking, causing it to rest against the stop plate, Fig. 10.
On diagonally split brake systems, two proportioners or pressure control valves are used. One
controls the left rear brake, the other the right rear brake. The proportioners or pressure control
valves are installed in the master cylinder rear brake outlet ports, Fig. 11.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Locations > ABS Solenoid Valves
Hydraulic Control Assembly - Antilock Brakes: Locations ABS Solenoid Valves
The solenoid valves are located inside the hydraulic modulator are not serviceable.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Locations > ABS Solenoid Valves > Page 6926
Hydraulic Control Assembly - Antilock Brakes: Locations Brake Pressure Modulator
The hydraulic modulator (also known as Brake Pressure Modulator (BPM) or Pressure Modulator
Valve (PMV)) is located on the front lefthand side of the engine compartment.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Locations > ABS Solenoid Valves > Page 6927
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Locations > Page 6928
Hydraulic Control Assembly - Antilock Brakes: Diagrams
Brake Pressure Modulator Valve (BPMV)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Locations > Page 6929
Brake Pressure Modulator Valve (BPMV) (With Electronic Brake Control Module (EBCM))
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Description and Operation > ABS Solenoid Valves
Hydraulic Control Assembly - Antilock Brakes: Description and Operation ABS Solenoid Valves
DESCRIPTION
The solenoid valves are located inside the hydraulic modulator are not serviceable. The solenoid
valves increase, decrease or maintain the brake fluid pressure to the wheel circuits. During
anti-lock braking the valves are controlled by signals received by the EBCM/EBTCM. During
normal braking, the valves are positioned in a pressure increase or open position.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Description and Operation > ABS Solenoid Valves > Page 6932
Hydraulic Control Assembly - Antilock Brakes: Description and Operation Hydraulic Modulator
Valve
DESCRIPTION
The hydraulic modulator (also known as Brake Pressure Modulator (BPM) or Pressure Modulator
Valve (PMV)) is located on the front lefthand side of the engine compartment, provides brake fluid
modulation for each individual wheel circuit as required during anti-lock braking. During anti-lock
braking, the modulator can maintain or reduce brake fluid pressure independent of the pressure
generated in the master cylinder.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Hydraulic Control Assembly Antilock Brakes > Component Information > Description and Operation > Page 6933
Hydraulic Control Assembly - Antilock Brakes: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Disconnect and remove air intake duct and resonator, then
position upper coolant hose aside. 3. Disconnect canister purge line at canister and position aside.
4. Remove modulator valve cover attaching screw and cover. 5. Disconnect modulator valve
electrical connector and ground wire. 6. Disconnect all hydraulic lines to modulator valve, then plug
pipes to prevent loss of fluid and fluid contamination. Note location of pipes for
installation reference.
7. Remove three modulator valve to bracket attaching nuts, then the modulator valve from vehicle.
8. Reverse procedure to install, then perform ABS system check as described in System
Diagnosis. See: Antilock Brakes / Traction Control
Systems/Testing and Inspection
NOTE: Ensure brake hydraulic pipes are installed correctly. Pipes that are crossed during
installation could cause wheel lock-up.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Master Cylinder >
Component Information > Specifications
Brake Master Cylinder: Specifications
Master Cylinder Bore Dia., Inch ...........................................................................................................
........................................................................ 1.125 Front Caliper Bore Dia., Inch ............................
............................................................................................................................................................
2.952 Wheel Cylinder Bore Dia., Inch .................................................................................................
.......................................................................................... 1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Master Cylinder >
Component Information > Service and Repair > Master Cylinder Disassembly/Assembly
Brake Master Cylinder: Service and Repair Master Cylinder Disassembly/Assembly
Dual Master Cylinder Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Master Cylinder >
Component Information > Service and Repair > Master Cylinder Disassembly/Assembly > Page 6939
Compact Master Cylinder Assembly
Master Cylinder Reservoir Removal. Composite Type
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Master Cylinder >
Component Information > Service and Repair > Master Cylinder Disassembly/Assembly > Page 6940
DISASSEMBLE
Refer to Figs. 19 and 20 when performing the following procedures. 1. Remove master cylinder
from vehicle as follows:
a. Disconnect and plug hydraulic lines. b. Remove two master cylinder attaching nuts, then the
master cylinder.
2. Remove reservoir cover and diaphragm. Discard old brake fluid in reservoir. 3. Inspect cover and
diaphragm. Replace if cut, cracked or deformed. 4. Remove fluid level switch, if equipped. 5. On
models with compact master cylinder, remove proportioner valve assembly, Fig. 20. 6. On all
models, depress primary piston and remove lock ring. 7. Plug primary fluid outlet (outlet nearest to
cowl when master cylinder is installed), then apply compressed air into secondary fluid outlet to
remove
primary and secondary pistons.
8. Remove spring retainer and seals from secondary piston. 9. Clamp master cylinder in a vise as
shown in Fig. 21, then remove reservoir using a pry bar. Remove reservoir grommets.
10. Inspect master cylinder bore for corrosion. Do not use abrasive material on master cylinder
bore. Replace if bore is corroded.
ASSEMBLE
Clean all parts not included in repair kit with brake fluid. Do not dry with compressed air. Lubricate
all rubber parts with clean brake fluid prior to installation. 1. Lubricate new reservoir grommets with
silicone brake lube, then press grommets into master cylinder body. Ensure grommets are properly
seated. 2. Lay reservoir upside down on flat, hard surface. Press master cylinder body onto
reservoir using rocking motion. 3. Install new seals on secondary piston, then the spring retainer. 4.
Install spring and secondary piston assembly into cylinder. 5. Install primary piston. Depress
primary piston into cylinder, then install lock ring. 6. Install fluid level switch, if equipped. 7. On
models with compact master cylinder, install proportioner valve assembly, Fig. 20. 8. On all
models, fit diaphragm into reservoir cover, then install cover onto reservoir. 9. Install master
cylinder and bleed brake system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Brake Master Cylinder >
Component Information > Service and Repair > Master Cylinder Disassembly/Assembly > Page 6941
Brake Master Cylinder: Service and Repair Master Cylinder Replace
1. Disconnect wire connector from brake warning pressure switch, if equipped. 2. Disconnect brake
lines from master cylinder. 3. Remove master cylinder mounting nuts, then the master cylinder. 4.
On models with separate fluid reservoirs, remove reservoir. 5. On all models, reverse procedure to
install, noting the following:
a. Refer to Master Cylinder Push Rod for procedures on push rod adjustments. b. Bleed brakes as
described under Brake Bleeding. Refer to Brakes/Service and Repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Wheel Cylinder > Component
Information > Technical Service Bulletins > Brakes - Wheel Cylinder Inspection Guidelines
Wheel Cylinder: Technical Service Bulletins Brakes - Wheel Cylinder Inspection Guidelines
Bulletin No.: 03-05-24-001A
Date: March 21, 2005
INFORMATION
Subject: Service Information Regarding Rear Brake Drum Wheel Cylinder Inspections
Models: 2005 and Prior GM Passenger Cars and Trucks 2005 and Prior Saturn Vehicles
with Rear Drum Brakes
Supercede:
This bulletin is being revised add model years and include all GM vehicles. Please discard
Corporate Bulletin Number 03-05-24-001 (Section 03 - Suspension).
This bulletin provides information on proper inspection of rear drum brake wheel cylinders.
Important:
It is not recommended that dust boots be removed during inspection processes as dirt and debris
could contaminate the wheel cylinder bore causing premature wear of the wheel cylinder. In
addition, most bores should look damp and some lubricant may drip out from under the boot as a
result of lubricant being present.
All rear drum brake wheel cylinders are assembled with a lubricant to aid in assembly, provide an
anti-corrosion coating to the cylinder bore, and lubricate internal rubber components. As a result of
this lubrication process, it is not uncommon for some amount of lubricant to accumulate at the ends
of the cylinder under the dust boot.
Over time, the lubricant may work its way to the outside of the boot and cause an area of the boot
to look damp. Evidence of a damp area on the boot does not indicate a leak in the cylinder.
However, if there is excessive wetness (i.e. drips) coming from the boot area of the wheel cylinder,
it could indicate a brake hydraulic fluid leak requiring wheel cylinder replacement. (Refer to the
Wheel Cylinder Replacement procedures in the appropriate Service Manual.)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Wheel Cylinder > Component
Information > Technical Service Bulletins > Page 6946
Wheel Cylinder: Specifications
Wheel Cylinder Bore Diameter 1 in
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Hydraulic System, Brakes > Wheel Cylinder > Component
Information > Technical Service Bulletins > Page 6947
Wheel Cylinder: Service and Repair
Fig. 33 Exploded View Of Wheel Cylinder
1. Raise and support vehicle.
2. Remove wheel, drum and brake shoes.
3. Disconnect hydraulic line at wheel cylinder. Do not pull metal line away from cylinder, as this
may kink or bend line. Line will separate from cylinder when cylinder is moved away from brake
backing plate.
4. Remove wheel cylinder-to-brake plate attaching screws, then the wheel cylinder.
5. Remove boots, pistons, springs and cups from cylinder, Fig. 33.
6. Clean all parts with brake fluid.
7. Inspect cylinder bore. A scored bore may be honed as long as the diameter is not increased by
more than .005 inch. Replace worn or damaged parts as necessary.
8. Ensure hands are clean before proceeding with assembly. Lubricate cylinder wall and rubber
cups with brake fluid, then install springs, cups, pistons and boots in housing.
9. Wipe end of hydraulic line to remove any foreign matter, then place wheel cylinder in position.
Enter tubing into cylinder and start threads on fitting.
10. Secure cylinder to backing plate, then complete tightening of tubing fitting.
11. Install brake shoes, drum and wheel.
12. Bleed system as outlined previously, then adjust brakes.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Parking Brake System > Parking Brake Warning Switch >
Component Information > Locations > Park Brake Indicator Switch
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Parking Brake System > Parking Brake Warning Switch >
Component Information > Locations > Park Brake Indicator Switch > Page 6953
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Description and Operation > Power Brake Unit
Vacuum Brake Booster: Description and Operation Power Brake Unit
Fig. 1 Exploded View Of AC-Delco Tandem Diaphragm Booster
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Description and Operation > Power Brake Unit > Page 6959
Fig. 2 Exploded View Of Power Head Assembly. AC-Delco Tandem Diaphragm Booster
DESCRIPTION
This unit utilizes a vacuum power chamber, consisting of a front and rear shell, housing divider,
front and rear diaphragm, plate assemblies, hydraulic pushrod and a diaphragm return spring, Fig.
1 and 2 .
OPERATION
In normal operating mode, with service brakes in released position, the booster operates with
vacuum on both sides of its diaphragms. When brakes are applied, air at atmospheric pressure is
admitted to one side of each diaphragm to provide power assist. When the service brake is
released, atmospheric air is shut off from one side of each diaphragm. The air is then drawn from
the booster through the vacuum check valve to the vacuum source.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Description and Operation > Power Brake Unit > Page 6960
Vacuum Brake Booster: Description and Operation General Service
Two basic types of power assist mechanisms are used: vacuum assist diaphragm assemblies,
which use engine vacuum or, in some cases vacuum pressure developed by an external vacuum
pump. The second type is a hydraulic pressure assist mechanism, which use pressure developed
by an external pump (usually the power steering pump). Both systems act to increase the force
exerted on the master cylinder piston by the operator. This in turn increases the hydraulic pressure
delivered to the wheel cylinders, while decreasing driver effort necessary to obtain acceptable
stopping performance.
Vacuum assist units are similar in operation and get their energy by opposing engine vacuum to
atmospheric pressure. A piston and cylinder, flexible diaphragm (bellows) utilize this energy to
provide brake assistance. The fundamental difference between these types of vacuum assist
systems lies simply in how the diaphragm within the power unit is suspended when the brakes are
not applied.
In order to properly diagnose vacuum assist system malfunctions it is important to know whether
the diaphragm within a power unit is air suspended or vacuum suspended. Air-suspended units are
under atmospheric pressure until the brakes are applied. Engine vacuum is then admitted, causing
the piston or diaphragm to move (or the bellows to collapse). Vacuum-suspended types are
balanced with engine vacuum until the brake pedal is depressed, allowing atmospheric pressure to
unbalance the unit and apply force to the brake system.
Regardless of whether the brakes are vacuum or hydraulically assisted, certain general service
procedures apply. Only specified, clean brake fluid should be used in brake system. On
hydro-boost systems, use of the specified hydraulic fluid in the boost circuit is essential to proper
system operation. Care must be taken not to mix the fluids of the two separate operating circuits.
Use of improper fluids, or contaminated fluid will cause damage to the seals and valves.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Testing and Inspection > Brakes Grab
Vacuum Brake Booster: Testing and Inspection Brakes Grab
1. Faulty control valve.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Testing and Inspection > Brakes Grab > Page 6963
Vacuum Brake Booster: Testing and Inspection Hard Pedal
1. Internal vacuum leak. 2. Faulty control valve.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Testing and Inspection > Brakes Grab > Page 6964
Vacuum Brake Booster: Testing and Inspection Slow or No Release
1. Faulty pushrod adjustment. 2. Bind in linkage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Adjustments > Gauge Method
Vacuum Brake Booster: Adjustments Gauge Method
Fig. 7 Master Cylinder Pushrod Adjustment. AC-Delco Type Vacuum Booster
On these models, the master cylinder pushrod length is fixed and is usually only checked after the
unit has been overhauled. 1. Assemble booster unit and install pushrod, ensuring pushrod is fully
seated. 2. Position go/no go gauge furnished in repair kit over pushrod as shown in Fig. 7 3. If
pushrod height is not within limits of gauge, install service adjustable pushrod and adjust rod to
obtain correct height. 4. Install power unit and check adjustment, ensuring master cylinder
compensating port is open with engine running and brake pedal released.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Adjustments > Gauge Method > Page 6967
Vacuum Brake Booster: Adjustments Air Method
1. Be sure master cylinder attaching nuts are tight. 2. Remove master cylinder filler cap. 3. With
brake released, force compressed air into the hydraulic outlet of the master cylinder. Regulate air
pressure to a value of approximately 5
psi, to prevent spraying brake fluid from master cylinder. Care must be taken not to allow brake
fluid to contact painted surfaces of vehicle, skin or eyes, as damage or personal injury will result.
4. If air passes through the compensating port, which is the smaller of the two holes in the bottom
of the master cylinder reservoir, the adjustment is
satisfactory.
5. If air does not flow through the compensating port, adjust the pushrod as required, either by
means of the adjustment screw (if provided) or by
adding shims between the master cylinder and power unit shell until the air flows freely.
6. Reconnect brake lines and bleed system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Power Brake Assist > Vacuum Brake Booster > Component
Information > Adjustments > Page 6968
Vacuum Brake Booster: Service and Repair
The tandem diaphragm type power brake booster is no longer serviceable and should be replaced
as an assembly,
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Relays and Modules - Brakes and Traction Control > ABS
Main Relay > Component Information > Service and Repair
ABS Main Relay: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Remove ABS modulator protective cover. 3. Remove relay
from modulator. 4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Relays and Modules - Brakes and Traction Control >
Electronic Brake Control Module > Component Information > Locations
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Relays and Modules - Brakes and Traction Control >
Electronic Brake Control Module > Component Information > Locations > Page 6976
Brake Pressure Modulator Valve (BPMV) (With Electronic Brake Control Module (EBCM))
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Relays and Modules - Brakes and Traction Control >
Electronic Brake Control Module > Component Information > Locations > Page 6977
Electronic Brake Control Module: Description and Operation
DESCRIPTION
The EBCM is a small control computer located under the trim panel on the lefthand side of the
passenger compartment on wagon models, and on the lefthand side of the luggage compartment
on sedan models. This computer monitors the speed of each wheel and the electrical status of the
hydraulic modulator. The primary functions of EBCM are to detect wheel locking, control the brake
function while in anti-lock mode and monitor system for correct electrical operation. The EBCM also
controls the display of the ABS diagnostic trouble codes. If the EBCM detects a fault, it can disable
the ABS system and activate the ABS warning lamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Relays and Modules - Brakes and Traction Control >
Electronic Brake Control Module > Component Information > Locations > Page 6978
Electronic Brake Control Module: Service and Repair
REPLACEMENT
1. Disconnect battery ground cable. 2. Disconnect EBCM electrical connector. 3. Remove two
EBCM to bracket attaching nuts, then the EBCM from the vehicle. 4. Reverse procedure to install,
perform ABS system check as described in System Diagnosis. See: Antilock Brakes / Traction
Control
Systems/Testing and Inspection
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control > Brake
Fluid Level Sensor/Switch > Component Information > Description and Operation
Brake Fluid Level Sensor/Switch: Description and Operation
OPERATION
This sensor mounted on the master cylinder will activate the Brake Warning lamp if a low brake
fluid level is detected. The lamp will turn off once the fluid level is corrected.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control > Brake
Fluid Pressure Sensor/Switch > Component Information > Locations
LH Rear Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control > Brake
Fluid Pressure Sensor/Switch > Component Information > Locations > Page 6986
Brake Fluid Pressure Sensor/Switch: Description and Operation
Fig. 3 Pressure Differential Valve & Brake Warning Lamp Switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control > Brake
Fluid Pressure Sensor/Switch > Component Information > Locations > Page 6987
Fig. 4 Dual Master Cylinder W/Built In Warning Lamp Switch.
DESCRIPTION
In Fig. 3, as pressure falls in one system, the other system's normal pressure forces the piston to
the inoperative side, contacting the switch terminal, causing the warning lamp on the instrument
panel to glow.
In Fig. 4 shows the switch mounted directly in the master cylinder assembly. Whenever there is a
specified differential pressure, the switch piston will activate the brake failure warning switch and
cause the brake warning lamp to glow.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Parking Brake Warning Switch > Component Information > Locations > Park Brake Indicator Switch
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Parking Brake Warning Switch > Component Information > Locations > Park Brake Indicator Switch > Page 6992
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front
Wheel Speed Sensor: Locations Wheel Speed Sensor Lead, Front
LH Rear Engine Compartment
LH Front Frame Rail
RH Front Frame Rail
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 6997
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 6998
Wheel Speed Sensor: Locations Wheel Speed Sensor, Rear
LH Rear Frame Rail (Without Automatic Level Control)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Locations > Wheel Speed Sensor Lead, Front > Page 6999
Antilock Brake System Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Locations > Page 7000
Wheel Speed Sensor: Description and Operation
DESCRIPTION
These sensors transmit wheel speed information to the EBCM using a small amount of AC voltage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor
Wheel Speed Sensor: Service and Repair Left Front Wheel Speed Sensor
REPLACEMENT
1. Raise and support vehicle. 2. Disconnect wheel speed sensor harness connector and sensor
assembly connector from clip. 3. Disconnect speed sensor connector from harness connector. 4.
Remove sensor bracket attaching bolt from frame rail. 5. Disconnect wheel speed sensor assembly
harness with grommets from brackets and combination valve brake pipe clip. Note position of
grommets and harness for installation reference.
6. Remove speed sensor retaining bolt, then the speed sensor from steering knuckle. 7. Reverse
procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the knuckle and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Brakes and Traction Control > Sensors and Switches - Brakes and Traction Control >
Wheel Speed Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor > Page 7003
Wheel Speed Sensor: Service and Repair Rear Axle Speed Sensor
1. Raise and support vehicle.
2. Unclip sensor assembly connector and differential sensor connector, then separate the
connectors.
3. Disconnect speed sensor harness assembly wiring harness with gromments from sensor
bracket. Note position of grommets and harness for installation reference.
4. Remove sensor attaching bolt, then the sensor from the vehicle.
5. Reverse procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the axle housing and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
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Wheel Speed Sensor > Component Information > Service and Repair > Left Front Wheel Speed Sensor > Page 7004
Wheel Speed Sensor: Service and Repair Right Front Wheel Speed Sensor
REPLACEMENT
1. Disconnect forward lamp harness wheel speed sensor connector and wheel speed sensor
assembly connector from clip. 2. Disconnect forward lamp harness connector from wheel speed
sensor connector. 3. Raise and support vehicle. 4. Remove sensor bracket attaching bolt from
frame rail. 5. Remove sensor assembly harness with grommets from brackets. Note position of
grommets and harness for assembly reference. 6. Remove sensor retaining bolt, then the sensor
from vehicle. 7. Reverse procedure to install.
CAUTION: The wheel speed sensors are a tight fit into the knuckle and are to be pushed in by
hand. Do not hammer sensor into position. Proper installation of sensor assembly wire into the
bracket is critical. Failure to install wire on bracket could cause wire to come in contact with moving
parts, causing circuit damage.
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Switch > Component Information > Diagrams > Diagram Information and Instructions
Neutral Safety Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7011
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7012
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7013
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7016
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Neutral Safety Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7018
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7027
Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7028
Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Neutral Safety Switch: Service and Repair
Fig. 4 Mechanical Neutral Safety System. Tilt Column
Fig. 5 Mechanical Neutral Safety System. Standard Column
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Fig. 6 Mechanical Neutral Safety System In Park Position
MECHANICAL
Actuation of the ignition switch is prevented by a mechanical lockout system Fig. 4 AND 5,. which
prevents the lock cylinder from rotating when the selector lever is out of Park or Neutral. When the
selector lever is in Park or Neutral, the slots in the bowl plate and the finger on the actuator rod
align, allowing the finger to pass through the bowl plate in turn actuating the ignition switch, Fig. 6.
If the selector lever is in any position other than Park or Neutral, the finger contacts the bowl plate
when the lock cylinder is rotated, thereby preventing full travel of the lock cylinder.
ELECTRIC
On models incorporating an electric neutral start switch, the start switch, back-up light switch and
parking brake vacuum release valve are combined into one unit. This unit is mounted on the
steering column under the instrument panel.
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Chevrolet Workshop Manuals > Starting and Charging > Battery > Battery Cable > Positive, Battery Cable > System
Information > Locations
Engine Harness/U/Hood Electrical Center, Right Side
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Technical Service Bulletins > Tools - Released for CS Generator Diagnosis
Alternator: Technical Service Bulletins Tools - Released for CS Generator Diagnosis
File In Section: 6 - Engine
Bulletin No.: 83-64-09
Date: March, 1998
INFORMATION
Subject: New Tool J 41450-B, Released for CS Generator Diagnosis
Models: 1988-98 Passenger Cars and Light Trucks with CS-Series Generators
A new CS-Series Generator Tester, J 41450-B, has been sent to all dealers as part of the Essential
Tool Package. This tool will work on all CS-Series generators for past model years. The tool is
shown in Figure 1.
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Technical Service Bulletins > Tools - Released for CS Generator Diagnosis > Page 7057
Generator Not Operating Properly
The charts shown can be used in place of the diagnostic procedures in previous Service Manuals
when this new tool is used. This information will be included in the 1999 Service Manual.
Inspect the following before testing the generator:
^ The battery. Make sure the vehicle battery is in good condition and fully charged. Refer to Battery
Load Test.
^ The built in hydrometer in the battery. The green eye must be showing in the hydrometer.
^ The voltage across the battery terminals with all the loads OFF should be above 12 V. Refer to
Battery Load Test.
^ Make sure the battery connections are clean and tight.
^ The drive belt for damage or looseness.
^ The wiring harness at the generator. Make sure the harness connector is tight and latched. Make
sure the output terminal of the generator is connected to the vehicle battery (positive) generator
lead.
^ All the charging system related fuses and electrical connections for damage or looseness. Refer
to the starter and charging system schematics.
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Alternator: Specifications
Alternator Model [06] ...........................................................................................................................
..................................................................... CS-130 Rated Hot Output Amps ...................................
..............................................................................................................................................................
.. 100
[06] Service part identification code K60 (100 amp. alternator). Refer to the service parts
identification label located on the deck lid or the spare tire
cover.
Alternator Model [07] ...........................................................................................................................
..................................................................... CS-130 Rated Hot Output Amps ...................................
..............................................................................................................................................................
.. 105
[07] Service part identification code K68 (105 amp. alternator). Refer to the service parts
identification label located on the deck lid or the spare tire
cover.
Alternator Model [01] ...........................................................................................................................
..................................................................... CS-144 Rated Hot Output Amps ...................................
..............................................................................................................................................................
.. 124
[01] Except part identification code KG9.
Alternator Model [02] ...........................................................................................................................
..................................................................... CS-144 Rated Hot Output Amps ...................................
..............................................................................................................................................................
.. 140
[02] Service part identification code KG9 (140 amp. alternator).
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Component Location - Pictorial View
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Diagrams > Diagram Information and Instructions
Alternator: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Alternator: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Generator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Charging System > Alternator > Component Information >
Diagrams > Page 7094
Alternator: Service Precautions
1. Be certain that battery polarity is correct when servicing units. Reversed battery polarity will
damage rectifiers and regulators. 2. If booster battery is used for starting, be sure to use correct
polarity in hook up. 3. When a fast charger is used to charge a vehicle battery, the vehicle battery
cables should be disconnected unless the fast charger is equipped with a
special Alternator Protector, in which case the vehicle battery cables need not be disconnected.
Also the fast charger should never be used to start a vehicle as damage to rectifiers will result.
4. Unless the system includes a load relay or field relay, grounding the alternator output terminal
will damage the alternator and/or circuits. This is
true even when the system is not in operation since no circuit breaker is used and the battery is
applied to the alternator output terminal at all times. The field or load relay acts as a circuit breaker
in that it is controlled by the ignition switch.
5. Before making any on vehicle tests of the alternator or regulator, the battery should be checked
and the circuit inspected for faulty wiring or
insulation. loose or corroded connections and poor ground circuits.
6. Check alternator belt tension to be sure the belt is tight enough to prevent slipping under load. 7.
The ignition switch should be off and the battery ground cable disconnected before making any test
connections to prevent damage to the system. 8. The vehicle battery must be fully charged or a
fully charged battery may be installed for test purposes.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Charging System > Alternator > Component Information >
Diagrams > Page 7095
Alternator: Description and Operation
Fig. 1 Exploded View Of CS Type Alternator Rotor Drive End
Fig. 2 Exploded View Of CS Type Alternator Slip Ring End Components
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Charging System > Alternator > Component Information >
Diagrams > Page 7096
DESCRIPTION
The CS alternator is available in three sizes: CS-121, CS-130, CS-130D and CS-144. The
numerals denote the outer diameter of the stator laminations in millimeters and the letters CS stand
for charging system. The CS-144 can be serviced. The CS-121 and CS-130 series are serviced as
an assembly only.
The CS alternators, Fig. 1 and 2 , use a new type regulator and a diode trio is not used. A delta
stator, rectifier bridge, and rotor with slip rings and brushes are electrically similar to earlier
alternators. A conventional fan mounted next to the pulley pulls air through the assembly for
cooling. An internal fan mounted on the rotor pulls air through the slip ring end frame to cool
rectifier, bridge and regulator. Air is expelled through openings in the end frame. No periodic
maintenance is required.
OPERATION
CS-130 and CS-144 alternators may be used with only two connections. The battery positive BAT
terminal must be connected to a battery during operation. The second required connection is
through the indicator light, or a suitable external resistor to L terminal of the regulator which serves
to turn unit On at start up. Three other regulator terminals are available for optional use in vehicle
systems. The P terminal is connected to the stator, and may be connected to a tachometer or other
device. The F terminal is connected internally to field positive, and may be used as a fault indicator.
The S terminal may be connected externally to a voltage, such as battery voltage, to sense voltage
to be controlled.
The regulator voltage setting varies with temperature, and limits system voltage by controlling rotor
field current. Unlike others regulators, this regulator switches field current On and Off at a fixed
frequency about 400 cycles per second. By varying On-Off time, correct average field current is
obtained to provide proper system voltage. At high speeds, the On time may be 10% and Off time
90%. At low speeds with high electrical loads, On-Off time may be 90% and 10% respectively.
Alternator systems on some applications are controlled by a Body Control Module (BCM). If cause
of a system malfunction cannot be determined using the following test procedure, a problem in the
electronic control system is indicated.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Key > Component Information > Technical
Service Bulletins > Locks - Key Code Security Rules and Information
Key: Technical Service Bulletins Locks - Key Code Security Rules and Information
INFORMATION
Bulletin No.: 10-00-89-010
Date: May 27, 2010
Subject: Key Code Security Rules and Information on GM KeyCode Look-Up Application (Canada
Only)
Models:
2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER H2, H3 2009 and Prior
Saturn and Saab 2002 and Prior Isuzu
Attention:
This bulletin has been created to address potential issues and questions regarding KeyCode
security. This bulletin should be read by all parties involved in KeyCode activity, including dealer
operator, partner security coordinator, sales, service and parts departments. A copy of this bulletin
should be printed and maintained in the parts department for use as a reference.
Important U.S. dealers should refer to Corporate Bulletin Number 10-00-89-009.
Where Are Key Codes Located?
General Motors provides access to KeyCodes through three sources when a vehicle is delivered to
a dealer. Vehicle KeyCodes are located on the original vehicle invoice to the dealership. There is a
small white bar coded tag sent with most new vehicles that also has the key code printed on it.
Dealerships should make a practice of comparing the tag's keycode numbers to the keycode listed
on the invoice. Any discrepancy should be reported immediately to the GM of Canada Key Code
Inquiry Desk. Remember to remove the key tag prior to showing vehicles to potential customers.
The third source for Key codes is through the GM KeyCode Look-Up feature within the
OEConnection D2DLink application. KeyCode Look-Up currently goes back 17 previous model
years from the current model year.
When a vehicle is received by the dealership, care should be taken to safeguard the original
vehicle invoice and KeyCode tag provided with the vehicle. Potential customers should not have
access to the invoice or this KeyCode tag prior to the sale being completed. After a sale has been
completed, the KeyCode information belongs to the customer and General Motors.
Tip
Only the original invoice contains key code information, a re-printed invoice does not.
GM KeyCode Look-Up Application for GM of Canada Dealers
All dealers should review the General Motors of Canada KeyCode Look-Up Policies and
Procedures (Service Policy & Procedures Manual Section 3.1.6 "Replacement of VIN plates &
keys").
Please note that the KeyCode Access site is restricted. Only authorized users should be using this
application. Please see your Parts Manager for site authorized users. KeyCode Look-Up currently
goes back 17 years from current model year.
Important notes about security:
- Users may not access the system from multiple computers simultaneously.
- Users may only request one KeyCode at a time.
- KeyCode information will only be available on the screen for 2 minutes.
- Each user is personally responsible for maintaining and protecting their password.
- Never share your password with others.
- User Id's are suspended after 6 consecutive failed attempts.
- User Id's are disabled if not used for 90 days.
- Processes must be in place for regular dealership reviews.
- The Parts Manager (or assigned management) must have processes in place for employee
termination or life change events. Upon termination individuals access must be turned off
immediately and access should be re-evaluated upon any position changes within the dealership.
- If you think your password or ID security has been breached, contact Dealer Systems Support at
1-800-265-0573.
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Service Bulletins > Locks - Key Code Security Rules and Information > Page 7102
Each user will be required to accept the following agreement each time the KeyCode application is
used.
Key Code User Agreement
- Key codes are proprietary information belonging to General Motors Corporation and to the vehicle
owner.
- Unauthorized access to, or use of, key code information is unlawful and may subject the user to
criminal and civil penalties.
- This information should be treated as strictly confidential and should not be disclosed to anyone
unless authorized.
I will ensure that the following information is obtained prior to releasing any Key Code information:
1. Government issued picture ID (Drivers License) 2. Registration or other proof of ownership.
Registration should have normal markings from the Province that issued the registration and
possibly the
receipt for payment recorded as well.
Important
- GM takes this agreement seriously. Each user must be certain of vehicle ownership before giving
out key codes.
- When the ownership of the vehicle is in doubt, dealership personnel should not provide the
information.
Key code requests should never be received via a fax or the internet and key codes should never
be provided to anyone in this manner. A face to face contact with the owner of the vehicle is the
expected manner that dealers will use to release a key code or as otherwise stipulated in this
bulletin or other materials.
- Key codes should NEVER be sent via a fax or the internet.
- Each Dealership should create a permanent file to document all KeyCode Look Up transactions.
Requests should be filed by VIN and in each folder retain copies of the following:
- Government issued picture ID (Drivers License)
- Registration or other proof of ownership.
- Copy of the paid customer receipt which has the name of the employee who cut and sold the key
to the customer.
- Do not put yourself or your Dealership in the position of needing to "explain" a KeyCode Look Up
to either GM or law enforcement officials.
- Dealership Management has the ability to review all KeyCode Look-Up transactions.
- Dealership KeyCode documentation must be retained for two years.
Frequently Asked Questions (FAQs) for GM of Canada Dealers
How do I request a KeyCode for customer owned vehicle that is not registered?
Scrapped, salvaged or stored vehicles that do not have a current registration should still have the
ownership verified by requesting the vehicle title, current insurance policy and / or current lien
holder information from the customers financing source. If you cannot determine if the customer is
the owner of the vehicle, do not provide the key code information. In these cases, a short
description of the vehicle (scrapped, salvaged, etc.) and the dealership location should be kept on
file. Any clarifying explanation should be entered into the comments field.
How do I document a KeyCode request for a vehicle that is being repossessed?
The repossessor must document ownership of the vehicle by providing a court ordered
repossession order and lien-holder documents prior to providing key code information. Copies of
the repossessors Drivers License and a business card should be retained by the dealership for
documentation.
What do I do if the registration information is locked in the vehicle?
Every effort should be made to obtain complete information for each request. Each Dealership will
have to decide on a case by case basis if enough information is available to verify the customer's
ownership of the vehicle. Other forms of documentation include vehicle title, insurance policy, and
or current lien information from the customers financing source. Dealership Management must be
involved in any request without complete information. If you cannot determine if the customer is the
owner of the vehicle, do not provide the key code information.
Can I get a print out of the information on the screen?
It is important to note that the Key Code Look Up Search Results contain sensitive and/or
proprietary information. For this reason GM recommends against printing it. If the Search Results
must be printed, store and/or dispose of the printed copy properly to minimize the risk of improper
or illegal use.
Who in the dealership has access to the KeyCode application?
Dealership Parts Manager (or assigned management) will determine, and control, who is
authorized to access the KeyCode Look Up application. However, we anticipate that dealership
parts and service management will be the primary users of the application. The KeyCode Look Up
application automatically tracks each user activity session. Information tracked by the system
includes: User name, User ID, all other entered data and the date/time of access.
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Service Bulletins > Locks - Key Code Security Rules and Information > Page 7103
What if I input the VIN incorrectly?
If an incorrect VIN is entered into the system (meaning that the system does not recognize the VIN
or that the VIN has been entered incorrectly) the system will return an error message.
If I am an authorized user for the KeyCode application, can I access the application from home?
Yes.
What if I suspect key code misuse?
Your dealership should communicate the proper procedures for requesting key codes. Any
suspicious activity either within the dealership or externally should be reported to Dealer Systems
Support at 1-800-265-0573 or GM of Canada Key Code Inquiry Desk at 1-905-644-4892.
Whose key codes can I access through the system?
At this time the following Canadian vehicle codes are available through the system: Chevrolet,
Cadillac, Buick, Pontiac, GMC, HUMMER (H2 and H3 only), Oldsmobile, Saturn, Saab and Isuzu
(up to 2002 model year) for a maximum of 17 model years.
What should I do if I enter a valid VIN and the system does not produce any key code information?
Occasionally, the KeyCode Look Up application may not produce a key code for a valid VIN. This
may be the result of new vehicle information not yet available. In addition, older vehicle information
may have been sent to an archive status. If you do not receive a key code returned for valid VIN,
you should contact GM of Canada Key Code Inquiry Desk at 1-905-644-4892.
How do I access KeyCodes if the KeyCode Look-up system is down?
If the KeyCode Look-up system is temporarily unavailable, you can contact the original selling
dealer who may have it on file or contact GM of Canada Key Code Inquiry Desk at
1-905-644-4892. If the customer is dealing with an emergency lock-out situation, you need to have
the customer contact Roadside assistance, OnStar if subscribed, or 911.
What should I do if the KeyCode from the look-up system does not work on the vehicle?
On occasion a dealer may encounter a KeyCode that will not work on the vehicle in question. In
cases where the KeyCode won't work you will need to verify with the manufacturer of the cutting
equipment that the key has been cut correctly. If the key has been cut correctly you may be able to
verify the proper KeyCode was given through the original selling dealer. When unable to verify the
KeyCode through the original selling dealer contact GM of Canada Key Code Inquiry Desk at
1-905-644-4892. If the key has been cut correctly and the code given does not work, the lock
cylinder may have been changed. In these situations following the proper SI document for recoding
a key or replacing the lock cylinder may be necessary.
How long do I have to keep KeyCode Records?
Dealership KeyCode documentation must be retained for two years.
Can I get a KeyCode changed in the Look-Up system?
Yes, KeyCodes can be changed in the Look-Up system if a lock cylinder has been changed.
Contact GM of Canada Key Code Inquiry Desk at 1-905-644-4892.
What information do I need before I can provide a driver of a company fleet vehicle Keys or
KeyCode information?
The dealership should have a copy of the individual's driver's license, proof of employment and
registration. If there is any question as to the customer's employment by the fleet company, the
dealer should attempt to contact the fleet company for verification. If there is not enough
information to determine ownership and employment, this information should not be provided.
How do I document a request from an Independent Repair facility for a KeyCode or Key?
The independent must provide a copy of their driver's license, proof of employment and signed
copy of the repair order for that repair facility. The repair order must include customer's name,
address, VIN, city, province and license plate number. Copies of this information must be included
in your dealer KeyCode file.
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Chevrolet Workshop Manuals > Starting and Charging > Starting System > Key > Component Information > Technical
Service Bulletins > Locks - Key Code Security Rules and Information > Page 7104
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions
Neutral Safety Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions > Page 7109
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions > Page 7110
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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> Diagrams > Diagram Information and Instructions > Page 7111
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions > Page 7112
Fig.2-Symbols (Part 2 Of 3)
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Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions > Page 7113
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions > Page 7114
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Chevrolet Workshop Manuals > Starting and Charging > Starting System > Neutral Safety Switch > Component Information
> Diagrams > Diagram Information and Instructions > Page 7115
Neutral Safety Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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> Diagrams > Diagram Information and Instructions > Page 7116
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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> Diagrams > Diagram Information and Instructions > Page 7133
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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> Diagrams > Diagram Information and Instructions > Page 7134
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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> Diagrams > Diagram Information and Instructions > Page 7135
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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> Diagrams > Diagram Information and Instructions > Page 7136
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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> Diagrams > Diagram Information and Instructions > Page 7137
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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> Diagrams > Diagram Information and Instructions > Page 7139
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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> Diagrams > Page 7140
Neutral Safety Switch: Service and Repair
Fig. 4 Mechanical Neutral Safety System. Tilt Column
Fig. 5 Mechanical Neutral Safety System. Standard Column
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Fig. 6 Mechanical Neutral Safety System In Park Position
MECHANICAL
Actuation of the ignition switch is prevented by a mechanical lockout system Fig. 4 AND 5,. which
prevents the lock cylinder from rotating when the selector lever is out of Park or Neutral. When the
selector lever is in Park or Neutral, the slots in the bowl plate and the finger on the actuator rod
align, allowing the finger to pass through the bowl plate in turn actuating the ignition switch, Fig. 6.
If the selector lever is in any position other than Park or Neutral, the finger contacts the bowl plate
when the lock cylinder is rotated, thereby preventing full travel of the lock cylinder.
ELECTRIC
On models incorporating an electric neutral start switch, the start switch, back-up light switch and
parking brake vacuum release valve are combined into one unit. This unit is mounted on the
steering column under the instrument panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Motor > Starter Drive/Bendix >
Component Information > Testing and Inspection > Drive Clutch Failure - A/C Delco
Starter Drive/Bendix: Testing and Inspection Drive Clutch Failure - A/C Delco
The overrunning clutch type drive seldom becomes so worn that it fails to engage since it is directly
activated by a fork and lever. The only thing that is likely to happen is that, once engaged, it will not
turn the engine because the clutch itself is worn out. A much more frequent difficulty and one that
rapidly wears ring gear and teeth is partial engagement. Proper meshing of the pinion is controlled
by the end clearance between the pinion gear and the starter housing or pinion stop, if used.
On some starters, the solenoids are completely enclosed in the starter housing and the pinion
clearance is not adjustable. If the clearance is not correct, the starter must be disassembled and
checked for excessive wear of solenoid linkage, shift lever mechanism, or improper assembly of
parts.
Failure of the overrunning clutch drive to disengage is usually caused by binding between the
armature shaft and the drive. If the drive, particularly the clutch, shows signs of overheating it
indicates that it is not disengaging immediately after the engine starts. If the clutch is forced to
overrun too long, it overheats and turns a bluish color. For the cause of the binding, look for rust or
gum between the armature shaft and the drive, or for burred splines. Excess oil on the drive will
lead to gumming, and inadequate air circulation in the flywheel housing will cause rust.
Overrunning clutch drives cannot be overhauled in the field so they must be replaced. In cleaning,
never soak them in a solvent because the solvent may enter the clutch and dissolve the sealed-in
lubricant. Wipe them off lightly with kerosene and lubricate them sparingly with SAE 10 or 10W oil.
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Component Information > Testing and Inspection > Drive Clutch Failure - A/C Delco > Page 7147
Starter Drive/Bendix: Testing and Inspection Drive Failure - A/C Delco
When a Bendix type drive doesn't engage the cause usually is one of three things: either the drive
spring is broken, one of the drive spring bolts has sheared off, or the screw shaft threads won't
allow the pinion to travel toward the flywheel. In the first two cases, remove the drive by unscrewing
the setscrew under the last coil of the drive spring and replace the broken parts. Gummed or rusty
screw shaft threads are fairly common causes of Bendix drive failure and are easily cleaned with a
little kerosene or steel wool, depending on the trouble. Here again, as in the case of overrunning
clutch drives, use light oil sparingly, and be sure the flywheel housing has adequate ventilation.
There is usually a breather hole in the bottom of the flywheel housing which should be open.
The failure of a Bendix drive to disengage or to mesh properly is most often caused by gummed or
rusty screw shaft threads. When this is not true, look for mechanical failure within the drive itself.
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Component Information > Testing and Inspection > Drive Clutch Failure - A/C Delco > Page 7148
Starter Drive/Bendix: Testing and Inspection Starter Drive Troubles - AC Delco
Starter drive troubles are easy to diagnose and they usually cannot be confused with ordinary
starter difficulties. If the starter does not turn over at all or if it drags, look for trouble in the starter or
electrical supply system. Concentrate on the starter drive or ring gear if the starter is noisy, if it
turns but does not engage the engine, or if the starter won't disengage after the engine is started.
After the starter is removed, the trouble can usually be located quickly.
Worn or chipped ring gear or starter pinion are the usual causes of noisy operation. Before
replacing either or both of these parts try to find out what caused the damage. With the Bendix type
drive, incomplete engagement of the pinion with the ring gear is a common cause of tooth damage.
The wrong pinion clearance on starter drives of the overrunning clutch type leads to poor meshing
of the pinion and ring gear and too rapid tooth wear.
A less common cause of noise with either type of drive is a bent starter armature shaft. When this
shaft is bent, the pinion gear alternately binds and then only partly meshes with the ring gear. Most
manufacturers specify a maximum of 0.003 inch radial runout on the armature shaft.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Locations
Lower Right Side Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions
Starter Solenoid: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Diagrams > Diagram Information and Instructions > Page 7159
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Starter Solenoid: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7177
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7178
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7179
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7180
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7181
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7182
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7183
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Diagram Information and Instructions > Page 7184
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Starting System > Starter Solenoid > Component Information >
Diagrams > Page 7185
Starter Solenoid: Description and Operation
DESCRIPTION
The solenoid switch on a cranking motor not only closes the circuit between the battery and the
cranking motor but also shifts the drive pinion into mesh with the engine flywheel ring gear. This is
done by means of a linkage between the solenoid switch plunger and the shift lever on the cranking
motor.
OPERATION
There are two windings in the solenoid; a pull-in winding and a hold-in winding. Both windings are
energized when the external control switch is closed. They produce a magnetic field which pulls the
plunger in so that the drive pinion is shifted into mesh, and the main contacts in the solenoid switch
are closed to connect the battery directly to the cranking motor. Closing the main switch contacts
shorts out the pull-in winding since this winding is connected across the main contacts. The
magnetism produced by the hold-in winding is sufficient to hold the plunger in, and shorting out the
pull-in winding reduces drain on the battery. When the control switch is opened, it disconnects the
hold-in winding from the battery. When the hold-in winding is disconnected from the battery, the
shift lever spring withdraws the plunger from the solenoid, opening the solenoid switch contacts
and at the same time withdrawing the drive pinion from mesh. Proper operation of the switch
depends on maintaining a definite balance between the magnetic strength of the pull-in and hold-in
windings.
This balance is established in the design by the size of the wire and the number of turns specified.
An open circuit in the hold-in winding or attempts to crank with a discharged battery will cause the
switch to chatter.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Auxiliary Power Outlet >
Component Information > Technical Service Bulletins > Customer Interest for Auxiliary Power Outlet: > 99-08-45-005 > Nov
> 99 > Accessory Receptacle/Cigar Lighter - Inoperative
Auxiliary Power Outlet: Customer Interest Accessory Receptacle/Cigar Lighter - Inoperative
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-45-005
Date: November, 1999
TECHNICAL
Subject: Accessory Receptacle/Cigar Lighter is Inoperative (Check Aftermarket Device Plug for
Short to Ground)
Models: 1995-2000 Passenger Cars and Trucks
Condition
Some customers may comment that the cigar lighter or the accessory receptacle is inoperative; or
that the internal fuse (within the plug on an aftermarket device), blows intermittently.
Cause
Certain aftermarket devices have a newly designed power plug with an internal mini fuse. The mini
fuse may have an external terminal (which may be used to externally check the fuse). If the mini
fuse external test terminal is not recessed into the mini fuse body, it may come in contact with the
shell of the vehicle receptacle and cause the fuse (of either the vehicle or the aftermarket device),
to blow intermittently.
Correction
Test the aftermarket device plug for short to ground. The following step may be performed at the
customer's expense. As this is not a defect in material, design or workmanship of the vehicle, it
would be the owner's responsibility.
1. Place a piece of tape over the mini fuse terminal temporarily.
2. Explain to the customer that the fuse for the device must have no exposed terminals, and that
finding one would be his responsibility.
3. Refer the customer to the manufacturer of the aftermarket device for a new plug.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Auxiliary Power Outlet >
Component Information > Technical Service Bulletins > All Technical Service Bulletins for Auxiliary Power Outlet: >
99-08-45-005 > Nov > 99 > Accessory Receptacle/Cigar Lighter - Inoperative
Auxiliary Power Outlet: All Technical Service Bulletins Accessory Receptacle/Cigar Lighter Inoperative
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-45-005
Date: November, 1999
TECHNICAL
Subject: Accessory Receptacle/Cigar Lighter is Inoperative (Check Aftermarket Device Plug for
Short to Ground)
Models: 1995-2000 Passenger Cars and Trucks
Condition
Some customers may comment that the cigar lighter or the accessory receptacle is inoperative; or
that the internal fuse (within the plug on an aftermarket device), blows intermittently.
Cause
Certain aftermarket devices have a newly designed power plug with an internal mini fuse. The mini
fuse may have an external terminal (which may be used to externally check the fuse). If the mini
fuse external test terminal is not recessed into the mini fuse body, it may come in contact with the
shell of the vehicle receptacle and cause the fuse (of either the vehicle or the aftermarket device),
to blow intermittently.
Correction
Test the aftermarket device plug for short to ground. The following step may be performed at the
customer's expense. As this is not a defect in material, design or workmanship of the vehicle, it
would be the owner's responsibility.
1. Place a piece of tape over the mini fuse terminal temporarily.
2. Explain to the customer that the fuse for the device must have no exposed terminals, and that
finding one would be his responsibility.
3. Refer the customer to the manufacturer of the aftermarket device for a new plug.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Circuit Breaker > Component
Information > Locations
Fuse Block Details: Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Circuit Breaker > Component
Information > Locations > Page 7203
Fuse Block Details: Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Underhood Electrical Center <-->
[Electrical Accessory Panel] > Component Information > Locations > Fuse Block Detail: Underhood Electrical Center
U/Hood Electrical Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Underhood Electrical Center <-->
[Electrical Accessory Panel] > Component Information > Locations > Fuse Block Detail: Underhood Electrical Center > Page
7208
Underhood Electrical Center: Locations Underhood Electrical Center
Engine Compartment
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Underhood Electrical Center <-->
[Electrical Accessory Panel] > Component Information > Locations > Page 7209
U/Hood Electrical Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Technical Service Bulletins > Electrical - Aftermarket Fuse Warning
Fuse: Technical Service Bulletins Electrical - Aftermarket Fuse Warning
Bulletin No.: 07-08-45-002
Date: September 05, 2007
ADVANCED SERVICE INFORMATION
Subject: Service Alert: Concerns With Aftermarket Fuses in GM Vehicles
Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2008 and
Prior HUMMER H2, H3 2008 and Prior Saab 9-7X
Concerns with Harbor Freight Tools "Storehouse" Branded Blade Type Fuses
General Motors has become aware of a fuse recall by Harbor Freight Tools/Storehouse for a
variety of aftermarket fuses. In two cases, these fuses have not provided protection for the wiring
system of the vehicles they were customer installed in.
Upon testing the 15 amp version, it was found that the fuse still would not "open" when shorted
directly across the battery terminals.
How to Identify These Fuses
Packed in a 120 piece set, the fuse has a translucent, hard plastic, blue body with the amperage
stamped into the top. There are no white painted numbers on the fuse to indicate amperage. There
are no identifying marks on the fuse to tell who is making it. The fuses are known to be distributed
by Harbor Freight Tools but there may be other marketers, and packaging of this style of fuse. It
would be prudent to replace these fuses if found in a customers vehicle. Likewise, if wiring
overheating is found you should check the fuse panel for the presence of this style of fuse.
All GM dealers should use genuine GM fuses on the vehicles they service. You should also
encourage the use of GM fuses to your customers to assure they are getting the required electrical
system protection. GM has no knowledge of any concerns with other aftermarket fuses. If
additional information becomes available, this bulletin will be updated.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Locations > I/P Fuse Block
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Locations > I/P Fuse Block > Page 7216
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label
Fuse: Application and ID Instrument Panel (I/P) Fuse Block Label
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 7219
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 7220
Fuse: Application and ID Under Hood Electrical Center
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 7221
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse > Component Information >
Application and ID > Page 7222
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Locations > Auxiliary Fuse Block, Special Equipment Option (Seo)
Fuse Block: Locations Auxiliary Fuse Block, Special Equipment Option (Seo)
Under I/P
Behind LH I/P, Left Of Brake Pedal Bracket
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Locations > Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 7227
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Locations > Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 7228
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Locations > Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 7229
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Application and ID > Instrument Panel (I/P) Fuse Block Label
Fuse Block: Application and ID Instrument Panel (I/P) Fuse Block Label
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 7232
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Fuse Block > Component
Information > Application and ID > Instrument Panel (I/P) Fuse Block Label > Page 7233
Fuse Block: Application and ID Under Hood Electrical Center
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair
Grounding Point: Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7238
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7239
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7240
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7241
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7242
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Grounding Point > Component
Information > Technical Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7243
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Auxiliary Juction Block <-->
[Multiple Junction Connector] > Component Information > Locations
Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Relays and Modules - Power and
Ground Distribution > Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center
Convenience Center: Locations Convenience Center
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Relays and Modules - Power and
Ground Distribution > Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center >
Page 7252
Behind LH I/P, Left Of Brake Pedal Bracket
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Relays and Modules - Power and
Ground Distribution > Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center >
Page 7253
Under I/P
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Relays and Modules - Power and
Ground Distribution > Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center >
Page 7254
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Relays and Modules - Power and
Ground Distribution > Convenience Center <--> [Relay Box] > Component Information > Locations > Page 7255
Convenience Center: Application and ID
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Convenience Center <--> [Relay
Box] > Component Information > Locations > Convenience Center
Convenience Center: Locations Convenience Center
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Convenience Center <--> [Relay
Box] > Component Information > Locations > Convenience Center > Page 7260
Behind LH I/P, Left Of Brake Pedal Bracket
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Convenience Center <--> [Relay
Box] > Component Information > Locations > Convenience Center > Page 7261
Under I/P
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Convenience Center <--> [Relay
Box] > Component Information > Locations > Convenience Center > Page 7262
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Convenience Center <--> [Relay
Box] > Component Information > Locations > Page 7263
Convenience Center: Application and ID
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set
By Various Control Modules
Wiring Harness: Customer Interest Electrical - MIL ON/DTC's Set By Various Control Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set
By Various Control Modules > Page 7272
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set
By Various Control Modules > Page 7273
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set
By Various Control Modules > Page 7274
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10
> Electrical - MIL ON/DTC's Set By Various Control Modules
Wiring Harness: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control
Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10
> Electrical - MIL ON/DTC's Set By Various Control Modules > Page 7280
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10
> Electrical - MIL ON/DTC's Set By Various Control Modules > Page 7281
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10
> Electrical - MIL ON/DTC's Set By Various Control Modules > Page 7282
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair
Wiring Harness: All Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair > Page 7287
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair > Page 7288
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair > Page 7289
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair > Page 7290
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair > Page 7291
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10
> Electrical - Information For Electrical Ground Repair > Page 7292
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 >
Electrical - Instrument Panel & General Wiring Repair
Wiring Harness: All Technical Service Bulletins Electrical - Instrument Panel & General Wiring
Repair
Bulletin No.: 06-08-45-004
Date: May 02, 2006
INFORMATION
Subject: Instrument Panel (I/P), Body and General Wiring Harness Repair
Models: 2007 and Prior GM Cars and Trucks 2003-2007 HUMMER H2 2006-2007 HUMMER H3
Important:
A part restriction has been implemented on all Body and I/P harnesses and is being administered
by the PQC. If a body or I/P harness replacement is required, it can take 12-28 weeks for a
harness to be built and delivered to a dealer. The dealer technician is expected to repair any
harness damage as the first and best choice before replacing a harness.
In an effort to standardize repair practices, General Motors is requiring that all wiring harnesses be
repaired instead of replaced. If there is a question concerning which connector and/or terminal you
are working on, refer to the information in the appropriate Connector End Views in SI. The
Instruction Manual J 38125-620, which is sent with each new update of the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal remove information.
Important:
There are some parts in the J 38125 Terminal Repair Kit (i.e. SIR connector CPAs and heat shrink
tube (used in high heat area pigtail replacement) and some TPAs that are not available from
GMSPO. It is vitally important that each update to the J 38125 Terminal Repair Kit be done as soon
as it arrives at the dealer.
Utilize the Terminal Repair Kit (J 38125) to achieve an effective wiring repair. The Terminal Repair
Kit has been an essential tool for all GM Dealers since 1987. Replacement terminals and tools for
this kit are available through SPX/Kent Moore. Refer to Corporate Bulletin Number 06-08-45-001
for more information.
The Instruction Manual J 38125-620, which is sent with each new update to the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal removal information.
U.S. Dealers Only - Training courses (including Tech Assists, Emerging Issues, Web, IDL and
Hands-on) are available through the GM Training website. Refer to Resources and then Training
Materials for a complete list of available courses.
Canadian Dealers Only - Refer to the Training section of GM infoNet for a complete list of available
courses and a copy of the J 38125 Terminal Repair Kit Instruction Manual.
Wiring repair information is also available in Service Information (SI). The Wiring Repair section
contains information for the following types of wiring repairs:
- Testing for intermittent conditions and poor conditions
- Flat wire repairs
- GMLAN wiring repairs
- High temperature wiring repairs
- Splicing copper wire using splice clips
- Splicing copper wire using splice sleeves
- Splicing twisted or shielded cable
- Splicing inline harness diodes
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 >
Electrical - Instrument Panel & General Wiring Repair > Page 7297
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair
Wiring Harness: All Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair > Page 7303
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair > Page 7304
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair > Page 7305
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair > Page 7306
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair > Page 7307
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 >
Electrical - Information For Electrical Ground Repair > Page 7308
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 >
Electrical - Instrument Panel & General Wiring Repair
Wiring Harness: All Technical Service Bulletins Electrical - Instrument Panel & General Wiring
Repair
Bulletin No.: 06-08-45-004
Date: May 02, 2006
INFORMATION
Subject: Instrument Panel (I/P), Body and General Wiring Harness Repair
Models: 2007 and Prior GM Cars and Trucks 2003-2007 HUMMER H2 2006-2007 HUMMER H3
Important:
A part restriction has been implemented on all Body and I/P harnesses and is being administered
by the PQC. If a body or I/P harness replacement is required, it can take 12-28 weeks for a
harness to be built and delivered to a dealer. The dealer technician is expected to repair any
harness damage as the first and best choice before replacing a harness.
In an effort to standardize repair practices, General Motors is requiring that all wiring harnesses be
repaired instead of replaced. If there is a question concerning which connector and/or terminal you
are working on, refer to the information in the appropriate Connector End Views in SI. The
Instruction Manual J 38125-620, which is sent with each new update of the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal remove information.
Important:
There are some parts in the J 38125 Terminal Repair Kit (i.e. SIR connector CPAs and heat shrink
tube (used in high heat area pigtail replacement) and some TPAs that are not available from
GMSPO. It is vitally important that each update to the J 38125 Terminal Repair Kit be done as soon
as it arrives at the dealer.
Utilize the Terminal Repair Kit (J 38125) to achieve an effective wiring repair. The Terminal Repair
Kit has been an essential tool for all GM Dealers since 1987. Replacement terminals and tools for
this kit are available through SPX/Kent Moore. Refer to Corporate Bulletin Number 06-08-45-001
for more information.
The Instruction Manual J 38125-620, which is sent with each new update to the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal removal information.
U.S. Dealers Only - Training courses (including Tech Assists, Emerging Issues, Web, IDL and
Hands-on) are available through the GM Training website. Refer to Resources and then Training
Materials for a complete list of available courses.
Canadian Dealers Only - Refer to the Training section of GM infoNet for a complete list of available
courses and a copy of the J 38125 Terminal Repair Kit Instruction Manual.
Wiring repair information is also available in Service Information (SI). The Wiring Repair section
contains information for the following types of wiring repairs:
- Testing for intermittent conditions and poor conditions
- Flat wire repairs
- GMLAN wiring repairs
- High temperature wiring repairs
- Splicing copper wire using splice clips
- Splicing copper wire using splice sleeves
- Splicing twisted or shielded cable
- Splicing inline harness diodes
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Starting and Charging > Power and Ground Distribution > Wiring Harness > Component
Information > Technical Service Bulletins > All Other Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 >
Electrical - Instrument Panel & General Wiring Repair > Page 7313
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Auxiliary Power Outlet > Component Information >
Technical Service Bulletins > Customer Interest for Auxiliary Power Outlet: > 99-08-45-005 > Nov > 99 > Accessory
Receptacle/Cigar Lighter - Inoperative
Auxiliary Power Outlet: Customer Interest Accessory Receptacle/Cigar Lighter - Inoperative
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-45-005
Date: November, 1999
TECHNICAL
Subject: Accessory Receptacle/Cigar Lighter is Inoperative (Check Aftermarket Device Plug for
Short to Ground)
Models: 1995-2000 Passenger Cars and Trucks
Condition
Some customers may comment that the cigar lighter or the accessory receptacle is inoperative; or
that the internal fuse (within the plug on an aftermarket device), blows intermittently.
Cause
Certain aftermarket devices have a newly designed power plug with an internal mini fuse. The mini
fuse may have an external terminal (which may be used to externally check the fuse). If the mini
fuse external test terminal is not recessed into the mini fuse body, it may come in contact with the
shell of the vehicle receptacle and cause the fuse (of either the vehicle or the aftermarket device),
to blow intermittently.
Correction
Test the aftermarket device plug for short to ground. The following step may be performed at the
customer's expense. As this is not a defect in material, design or workmanship of the vehicle, it
would be the owner's responsibility.
1. Place a piece of tape over the mini fuse terminal temporarily.
2. Explain to the customer that the fuse for the device must have no exposed terminals, and that
finding one would be his responsibility.
3. Refer the customer to the manufacturer of the aftermarket device for a new plug.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Auxiliary Power Outlet > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Auxiliary Power Outlet: > 99-08-45-005 > Nov > 99 >
Accessory Receptacle/Cigar Lighter - Inoperative
Auxiliary Power Outlet: All Technical Service Bulletins Accessory Receptacle/Cigar Lighter Inoperative
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-45-005
Date: November, 1999
TECHNICAL
Subject: Accessory Receptacle/Cigar Lighter is Inoperative (Check Aftermarket Device Plug for
Short to Ground)
Models: 1995-2000 Passenger Cars and Trucks
Condition
Some customers may comment that the cigar lighter or the accessory receptacle is inoperative; or
that the internal fuse (within the plug on an aftermarket device), blows intermittently.
Cause
Certain aftermarket devices have a newly designed power plug with an internal mini fuse. The mini
fuse may have an external terminal (which may be used to externally check the fuse). If the mini
fuse external test terminal is not recessed into the mini fuse body, it may come in contact with the
shell of the vehicle receptacle and cause the fuse (of either the vehicle or the aftermarket device),
to blow intermittently.
Correction
Test the aftermarket device plug for short to ground. The following step may be performed at the
customer's expense. As this is not a defect in material, design or workmanship of the vehicle, it
would be the owner's responsibility.
1. Place a piece of tape over the mini fuse terminal temporarily.
2. Explain to the customer that the fuse for the device must have no exposed terminals, and that
finding one would be his responsibility.
3. Refer the customer to the manufacturer of the aftermarket device for a new plug.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Circuit Breaker > Component Information > Locations
Fuse Block Details: Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Circuit Breaker > Component Information > Locations >
Page 7331
Fuse Block Details: Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Underhood Electrical Center <--> [Electrical Accessory
Panel] > Component Information > Locations > Fuse Block Detail: Underhood Electrical Center
U/Hood Electrical Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Underhood Electrical Center <--> [Electrical Accessory
Panel] > Component Information > Locations > Fuse Block Detail: Underhood Electrical Center > Page 7336
Underhood Electrical Center: Locations Underhood Electrical Center
Engine Compartment
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Underhood Electrical Center <--> [Electrical Accessory
Panel] > Component Information > Locations > Page 7337
U/Hood Electrical Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Technical Service
Bulletins > Electrical - Aftermarket Fuse Warning
Fuse: Technical Service Bulletins Electrical - Aftermarket Fuse Warning
Bulletin No.: 07-08-45-002
Date: September 05, 2007
ADVANCED SERVICE INFORMATION
Subject: Service Alert: Concerns With Aftermarket Fuses in GM Vehicles
Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2008 and
Prior HUMMER H2, H3 2008 and Prior Saab 9-7X
Concerns with Harbor Freight Tools "Storehouse" Branded Blade Type Fuses
General Motors has become aware of a fuse recall by Harbor Freight Tools/Storehouse for a
variety of aftermarket fuses. In two cases, these fuses have not provided protection for the wiring
system of the vehicles they were customer installed in.
Upon testing the 15 amp version, it was found that the fuse still would not "open" when shorted
directly across the battery terminals.
How to Identify These Fuses
Packed in a 120 piece set, the fuse has a translucent, hard plastic, blue body with the amperage
stamped into the top. There are no white painted numbers on the fuse to indicate amperage. There
are no identifying marks on the fuse to tell who is making it. The fuses are known to be distributed
by Harbor Freight Tools but there may be other marketers, and packaging of this style of fuse. It
would be prudent to replace these fuses if found in a customers vehicle. Likewise, if wiring
overheating is found you should check the fuse panel for the presence of this style of fuse.
All GM dealers should use genuine GM fuses on the vehicles they service. You should also
encourage the use of GM fuses to your customers to assure they are getting the required electrical
system protection. GM has no knowledge of any concerns with other aftermarket fuses. If
additional information becomes available, this bulletin will be updated.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Locations > I/P Fuse
Block
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Locations > I/P Fuse
Block > Page 7344
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Application and ID >
Instrument Panel (I/P) Fuse Block Label
Fuse: Application and ID Instrument Panel (I/P) Fuse Block Label
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Application and ID >
Instrument Panel (I/P) Fuse Block Label > Page 7347
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Application and ID >
Instrument Panel (I/P) Fuse Block Label > Page 7348
Fuse: Application and ID Under Hood Electrical Center
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Usage Chart
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Application and ID >
Instrument Panel (I/P) Fuse Block Label > Page 7349
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse > Component Information > Application and ID >
Page 7350
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Locations >
Auxiliary Fuse Block, Special Equipment Option (Seo)
Fuse Block: Locations Auxiliary Fuse Block, Special Equipment Option (Seo)
Under I/P
Behind LH I/P, Left Of Brake Pedal Bracket
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Locations >
Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 7355
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Locations >
Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 7356
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Locations >
Auxiliary Fuse Block, Special Equipment Option (Seo) > Page 7357
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Application and ID
> Instrument Panel (I/P) Fuse Block Label
Fuse Block: Application and ID Instrument Panel (I/P) Fuse Block Label
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Application and ID
> Instrument Panel (I/P) Fuse Block Label > Page 7360
I/P Fuse Block
I/P Fuse Block
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Fuse Block > Component Information > Application and ID
> Instrument Panel (I/P) Fuse Block Label > Page 7361
Fuse Block: Application and ID Under Hood Electrical Center
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair
Grounding Point: Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7366
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7367
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7368
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7369
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7370
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Grounding Point > Component Information > Technical
Service Bulletins > Electrical - Information For Electrical Ground Repair > Page 7371
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Auxiliary Juction Block <--> [Multiple Junction Connector]
> Component Information > Locations
Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Relays and Modules - Power and Ground Distribution >
Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center
Convenience Center: Locations Convenience Center
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Relays and Modules - Power and Ground Distribution >
Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center > Page 7380
Behind LH I/P, Left Of Brake Pedal Bracket
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Relays and Modules - Power and Ground Distribution >
Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center > Page 7381
Under I/P
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Relays and Modules - Power and Ground Distribution >
Convenience Center <--> [Relay Box] > Component Information > Locations > Convenience Center > Page 7382
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Relays and Modules - Power and Ground Distribution >
Convenience Center <--> [Relay Box] > Component Information > Locations > Page 7383
Convenience Center: Application and ID
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Convenience Center <--> [Relay Box] > Component
Information > Locations > Convenience Center
Convenience Center: Locations Convenience Center
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Convenience Center <--> [Relay Box] > Component
Information > Locations > Convenience Center > Page 7388
Behind LH I/P, Left Of Brake Pedal Bracket
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Convenience Center <--> [Relay Box] > Component
Information > Locations > Convenience Center > Page 7389
Under I/P
Under I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Convenience Center <--> [Relay Box] > Component
Information > Locations > Convenience Center > Page 7390
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Convenience Center <--> [Relay Box] > Component
Information > Locations > Page 7391
Convenience Center: Application and ID
Fuse Block Details: Fuse Usage Chart
Underhood Electrical Center
Fuse Block Details
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control
Modules
Wiring Harness: Customer Interest Electrical - MIL ON/DTC's Set By Various Control Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control
Modules > Page 7400
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control
Modules > Page 7401
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > Customer Interest: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control
Modules > Page 7402
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10 > Electrical - MIL
ON/DTC's Set By Various Control Modules
Wiring Harness: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control
Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10 > Electrical - MIL
ON/DTC's Set By Various Control Modules > Page 7408
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10 > Electrical - MIL
ON/DTC's Set By Various Control Modules > Page 7409
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 09-06-03-004D > Dec > 10 > Electrical - MIL
ON/DTC's Set By Various Control Modules > Page 7410
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair
Wiring Harness: All Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair > Page 7415
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair > Page 7416
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair > Page 7417
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair > Page 7418
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair > Page 7419
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information
For Electrical Ground Repair > Page 7420
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 > Electrical - Instrument
Panel & General Wiring Repair
Wiring Harness: All Technical Service Bulletins Electrical - Instrument Panel & General Wiring
Repair
Bulletin No.: 06-08-45-004
Date: May 02, 2006
INFORMATION
Subject: Instrument Panel (I/P), Body and General Wiring Harness Repair
Models: 2007 and Prior GM Cars and Trucks 2003-2007 HUMMER H2 2006-2007 HUMMER H3
Important:
A part restriction has been implemented on all Body and I/P harnesses and is being administered
by the PQC. If a body or I/P harness replacement is required, it can take 12-28 weeks for a
harness to be built and delivered to a dealer. The dealer technician is expected to repair any
harness damage as the first and best choice before replacing a harness.
In an effort to standardize repair practices, General Motors is requiring that all wiring harnesses be
repaired instead of replaced. If there is a question concerning which connector and/or terminal you
are working on, refer to the information in the appropriate Connector End Views in SI. The
Instruction Manual J 38125-620, which is sent with each new update of the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal remove information.
Important:
There are some parts in the J 38125 Terminal Repair Kit (i.e. SIR connector CPAs and heat shrink
tube (used in high heat area pigtail replacement) and some TPAs that are not available from
GMSPO. It is vitally important that each update to the J 38125 Terminal Repair Kit be done as soon
as it arrives at the dealer.
Utilize the Terminal Repair Kit (J 38125) to achieve an effective wiring repair. The Terminal Repair
Kit has been an essential tool for all GM Dealers since 1987. Replacement terminals and tools for
this kit are available through SPX/Kent Moore. Refer to Corporate Bulletin Number 06-08-45-001
for more information.
The Instruction Manual J 38125-620, which is sent with each new update to the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal removal information.
U.S. Dealers Only - Training courses (including Tech Assists, Emerging Issues, Web, IDL and
Hands-on) are available through the GM Training website. Refer to Resources and then Training
Materials for a complete list of available courses.
Canadian Dealers Only - Refer to the Training section of GM infoNet for a complete list of available
courses and a copy of the J 38125 Terminal Repair Kit Instruction Manual.
Wiring repair information is also available in Service Information (SI). The Wiring Repair section
contains information for the following types of wiring repairs:
- Testing for intermittent conditions and poor conditions
- Flat wire repairs
- GMLAN wiring repairs
- High temperature wiring repairs
- Splicing copper wire using splice clips
- Splicing copper wire using splice sleeves
- Splicing twisted or shielded cable
- Splicing inline harness diodes
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 > Electrical - Instrument
Panel & General Wiring Repair > Page 7425
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair
Wiring Harness: All Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair > Page 7431
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair > Page 7432
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair > Page 7433
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair > Page 7434
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair > Page 7435
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 10-08-45-001B > Oct > 10 > Electrical - Information For
Electrical Ground Repair > Page 7436
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 > Electrical - Instrument Panel
& General Wiring Repair
Wiring Harness: All Technical Service Bulletins Electrical - Instrument Panel & General Wiring
Repair
Bulletin No.: 06-08-45-004
Date: May 02, 2006
INFORMATION
Subject: Instrument Panel (I/P), Body and General Wiring Harness Repair
Models: 2007 and Prior GM Cars and Trucks 2003-2007 HUMMER H2 2006-2007 HUMMER H3
Important:
A part restriction has been implemented on all Body and I/P harnesses and is being administered
by the PQC. If a body or I/P harness replacement is required, it can take 12-28 weeks for a
harness to be built and delivered to a dealer. The dealer technician is expected to repair any
harness damage as the first and best choice before replacing a harness.
In an effort to standardize repair practices, General Motors is requiring that all wiring harnesses be
repaired instead of replaced. If there is a question concerning which connector and/or terminal you
are working on, refer to the information in the appropriate Connector End Views in SI. The
Instruction Manual J 38125-620, which is sent with each new update of the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal remove information.
Important:
There are some parts in the J 38125 Terminal Repair Kit (i.e. SIR connector CPAs and heat shrink
tube (used in high heat area pigtail replacement) and some TPAs that are not available from
GMSPO. It is vitally important that each update to the J 38125 Terminal Repair Kit be done as soon
as it arrives at the dealer.
Utilize the Terminal Repair Kit (J 38125) to achieve an effective wiring repair. The Terminal Repair
Kit has been an essential tool for all GM Dealers since 1987. Replacement terminals and tools for
this kit are available through SPX/Kent Moore. Refer to Corporate Bulletin Number 06-08-45-001
for more information.
The Instruction Manual J 38125-620, which is sent with each new update to the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal removal information.
U.S. Dealers Only - Training courses (including Tech Assists, Emerging Issues, Web, IDL and
Hands-on) are available through the GM Training website. Refer to Resources and then Training
Materials for a complete list of available courses.
Canadian Dealers Only - Refer to the Training section of GM infoNet for a complete list of available
courses and a copy of the J 38125 Terminal Repair Kit Instruction Manual.
Wiring repair information is also available in Service Information (SI). The Wiring Repair section
contains information for the following types of wiring repairs:
- Testing for intermittent conditions and poor conditions
- Flat wire repairs
- GMLAN wiring repairs
- High temperature wiring repairs
- Splicing copper wire using splice clips
- Splicing copper wire using splice sleeves
- Splicing twisted or shielded cable
- Splicing inline harness diodes
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Power and Ground Distribution > Wiring Harness > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Wiring Harness: > 06-08-45-004 > May > 06 > Electrical - Instrument Panel
& General Wiring Repair > Page 7441
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
Customer Interest: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening
Alignment: Customer Interest Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Important:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
Customer Interest: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening > Page 7451
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
Customer Interest: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening > Page 7452
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications
Alignment: All Technical Service Bulletins Steering/Suspension - Wheel Alignment Specifications
WARRANTY ADMINISTRATION
Bulletin No.: 05-03-07-009C
Date: December 09, 2010
Subject: Wheel Alignment Specifications, Requirements and Recommendations for GM Vehicles
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks
Supercede: This bulletin is being extensively revised to provide technicians and warranty
administrators with an all inclusive guide for wheel alignments. PLEASE FAMILIARIZE YOURSELF
WITH THESE UPDATES BEFORE PERFORMING YOUR NEXT GM WHEEL ALIGNMENT
SERVICE. Please discard Corporate Bulletin Number 05-03-07-009B (Section 03 - Suspension).
Purpose
The purpose of this bulletin is to provide retail, wholesale and fleet personnel with General Motors'
warranty service requirements and recommendations for customer concerns related to wheel
alignment. For your convenience, this bulletin updates and centralizes all of GM's Standard Wheel
Alignment Service Procedures, Policy Guidelines and bulletins on wheel alignment warranty
service.
Important PLEASE FAMILIARIZE YOURSELF WITH THESE UPDATES BEFORE PERFORMING
YOUR NEXT GM WHEEL ALIGNMENT SERVICE.
The following five (5) key steps are a summary of this bulletin and are REQUIRED in completing a
successful wheel alignment service.
1. Verify the vehicle is in an Original Equipment condition for curb weight, tires, wheels, suspension
and steering configurations. Vehicles
modified in any of these areas are not covered for wheel alignment warranty.
2. Review the customer concern relative to "Normal Operation" definitions. 3. Verify that vehicle is
within the "Mileage Policy" range. 4. Document wheel alignment warranty claims appropriately for
labor operations E2000 and E2020.
The following information must be documented or attached to the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
5. Use the proper wheel alignment equipment (preferred with print-out capability), process and the
appropriate calibration maintenance schedules.
Important If it is determined that a wheel alignment is necessary under warranty, use the proper
labor code for the repair. E2000 for Steering Wheel Angle and/or Front Toe set or E2020 for Wheel
Alignment Check/Adjust includes Caster, Camber and Toe set (Wheel alignment labor time for
other component repairs is to be charged to the component that causes a wheel alignment
operation.).
The following flowchart is to help summarize the information detailed in this bulletin and should be
used whenever a wheel alignment is performed.
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Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7458
Verify Original Equipment Condition of the Vehicle
- Verify that Original Equipment Tires and Wheels or Official GM Accessory Tires and Wheels are
on the vehicle.
- Verify that aftermarket suspension "Lift" or "Lowering" Kits or other suspension alterations have
NOT been done to the vehicle.
- Check for accidental damage to the vehicle; for example, severe pothole or curb impacts, collision
damage that may have affected the wheel alignment of the vehicle; e.g., engine cradles,
suspension control arms, axles, wheels, wheel covers, tires may show evidence of damage/impact.
- Check to be sure vehicle has seen "Normal Use" rather than abuse; e.g., very aggressive driving
may show up by looking at the tires and condition of the vehicle.
- Check for other additional equipment items that may significantly affect vehicle mass such as
large tool boxes, campers, snow plow packages (without the snowplow RPO), etc., especially in
trucks and cutaway/incomplete vehicles. Significant additional mass can affect trim height and
wheel alignment of the vehicle and may necessitate a customer pay wheel alignment when placed
semi-permanently in the vehicle (Upfitter instructions are to realign the vehicle after placement of
these types of items. (This typically applies to trucks and incomplete vehicles that can be upfit with
equipment such as the above.)
Customer Concerns, "Normal Operation" Conditions and "Mileage Policy"
Possible Concerns
The following are typical conditions that may require wheel alignment warranty service:
1. Lead/Pull: defined as "at a constant highway speed on a typical straight road, the amount of
effort required at the steering wheel to maintain the
vehicle's straight heading."
Important Please evaluate for the condition with hands-on the steering wheel. Follow the "Vehicle
Leads/Pulls" diagnostic tree located in SI to determine the cause of a lead/pull concern. Lead/Pull
concerns can be due to road crown or road slope, tires, wheel alignment or even in rare
circumstances a steering gear issue. Lead/pull concerns due to road crown are considered
"Normal Operation" and are NOT a warrantable condition -- the customer should be advised that
this is "Normal Operation."
Important Some customers may comment on a "Lead/Pull" when they hold the steering wheel in a
level condition. If so, this is more likely a "steering wheel angle" concern because the customer is
"steering" the vehicle to obtain a "level" steering wheel.
2. Steering wheel angle to the left or right (counter-clockwise or clockwise, respectively): Defined
as the steering wheel angle (clocking)
deviation from "level" while maintaining a straight heading on a typical straight road.
3. Irregular or Premature tire wear: Slight to very slight "feathering" or "edge" wear on the
shoulders of tires is NOT considered unusual and
should even out with a tire rotation; if the customer is concerned about a "feathering" condition of
the tires, the customer could be advised to rotate the tires earlier than the next scheduled
mileage/maintenance interval (but no later than the next interval). Be sure to understand the
customer's driving habits as this will also heavily influence the tire wear performance; tire wear from
aggressive or abusive driving habits is NOT a warrantable condition.
Important Slight or mild feathering, cupping, edge or heel/toe wear of tire tread shoulders is
"normal" and can show up very early in a tire/vehicle service mileage; in fact, some new tires can
show evidence of feathering from the factory. These issues do NOT affect the overall performance
and tread life of the tire. Dealer personnel should always check the customer's maintenance
records to ensure that tire inflation pressure is being maintained to placard and that the tires are
being rotated (modified-X pattern) at the proper mileage intervals. Wheel alignments are NOT to be
performed for the types of "Normal" Tire Feathering shown in Figures 1-4 below.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7459
Figure 1: Full Tread View - "NORMAL" Tire "Feathering" Wear on the Shoulder/Adjacent/Center
Ribs
Figure 2: Tire Shoulder View Example 1 - "NORMAL" Tire "Feathering" Wear on the Shoulder
Figure 3: Tire Shoulder View Example 2 - "NORMAL" Tire "Feathering" Wear
Figure 4: Detail Side View of Tire Shoulder Area - "NORMAL" Tire "Feathering" Wear
Important When a wheel alignment is deemed necessary for tire wear, be sure to document on the
repair order, in as much detail as possible, the severity and type of tire wear (e.g., severe center
wear or severe inside or outside shoulder wear) and the position of the tire on the vehicle (RF, LF,
LR, RR). Please note the customer's concern with the wear such as, noise, appearance, wear life,
etc. A field product report with pictures of the tire wear condition is recommended. Refer to
Corporate Bulletin Number 02-00-89-002J and #07-00-89-036C.
4. Other repairs that affect wheel alignment; e.g., certain component replacement such as
suspension control arm replacement, engine cradle
adjustment/replace, steering gear replacement, steering tie rod replace, suspension strut/shock,
steering knuckle, etc. may require a wheel alignment.
Important If other components or repairs are identified as affecting the wheel alignment, policy calls
for the wheel alignment labor time to be charged to the replaced/repaired component's labor
operation time rather than the wheel alignment labor operations.
Important Vibration type customer concerns are generally NOT due to wheel alignment except in
the rare cases; e.g., extreme diagonal wear across the tread. In general, wheel alignments are
NOT to be performed as an investigation/correction for vibration concerns.
"Normal Operation" Conditions
Vehicle Lead/Pull Due to Road Crown or Slope:
As part of "Normal Operation," vehicles will follow side-to-side or left to right road crown or slope.
Be sure to verify from the customer the types of roads they are driving as they may not recognize
the influence of road crown on vehicle lead/pull and steering wheel angle. If a vehicle requires
significant steering effort to prevent it from "climbing" the road crown there may be an issue to be
looked into further.
Important
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Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7460
A wheel alignment will generally NOT correct vehicles that follow the road crown since this is within
"Normal Operation."
Mileage Policy
The following mileage policy applies for E2020 and E2000 labor operations: Note
Wheel Alignment is NOT covered under the New Vehicle Limited Warranty for Express and Savana
Cutaway vehicles as these vehicles require Upfitters to set the wheel alignment after completing
the vehicles.
- 0-800 km (0-500 mi): E2000/E2020 claims ONLY allowed with Call Center Authorization. Due to
the tie down during shipping, the vehicle's suspension requires some time to reach normal
operating position. For this reason, new vehicles are generally NOT to be aligned until they have
accumulated at least 800 km (500 mi). A field product report should accompany any claim within
this mileage range.
- 801-12,000 km (501-7,500 mi):
- If a vehicle came from the factory with incorrect alignment settings, any resulting off-angle
steering wheel, lead/pull characteristics or the rare occurrence of excessive tire wear would be
apparent early in the life of the vehicle. The following policy applies:
- Vehicles 100% Factory Set/Measured for Caster/Camber/Toe - Escalade/ESV/EXT,
Tahoe/Suburban, Yukon/XL/Denali, Silverado/Sierra, Express/Savana, Corvette and
Colorado/Canyon: E2000/E2020 Claims: Call Center Authorization Required
- All Vehicles NOT 100% Factory Set/Measured for Caster/Camber/Toe as noted above:
E2000/E2020 Claims: Dealer Service Manager Authorization Required
- 12,001 km and beyond (7,501 miles and beyond): During this period, customers are responsible
for the wheel alignment expense or dealers may provide on a case-by case basis a one-time
customer enthusiasm claim up to 16,000 km (10,000 mi). In the event that a defective component
required the use of the subject labor operations, the identified defective component labor operation
will include the appropriate labor time for a wheel alignment as an add condition to the component
repair.
Important Only one wheel alignment labor operation claim (E2000 or E2020) may be used per VIN.
Warranty Documentation Requirements
When a wheel alignment service has been deemed necessary, the following items will need to be
clearly documented on/with the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
1. Document the customer concern in as much detail as possible on the repair order and in the
warranty administration system. Preferred examples:
- Steering wheel is off angle in the counterclockwise direction by approximately x degrees or
clocking position.
- Vehicle lead/pulls to the right at approximately x-y mph. Vehicle will climb the road crown. Severe,
Moderate or Slight.
- RF and LF tires are wearing on the outside shoulders with severe feathering.
Important In the event of a lead/pull or steering wheel angle concern, please note the direction of
lead/pull (left or right) or direction of steering wheel angle (clockwise or counterclockwise) on the
repair order and within the warranty claim verbatim.
Important In the event of a tire wear concern, please note the position on the vehicle and where the
wear is occurring on the tire; i.e., the RF tire is wearing on the inside shoulder.
2. Document the technician's findings on cause and correction of the issue. Examples:
- Reset LF toe from 0.45 degrees to 0.10 degrees and RF toe from -0.25 degrees to 0.10 degrees
to correct the steering wheel angle from 5 degrees counterclockwise to 0 degrees.
- Reset LF camber from 0.25 degrees to -0.05 degrees to correct the cross-camber condition of
+0.30 degrees to 0.00 degrees on the vehicle.
- Front Sum toe was found to be 0.50 degrees, reset to 0.20 degrees.
3. Print-out the "Before" and "After" wheel alignment measurements/settings and attach them to the
Repair Order or if print-out capability is not
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7461
available, measurements may also be clearly and legibly handwritten into the Wheel Alignment
Repair Order Questionnaire attached to this bulletin.
4. Attach the Wheel Alignment Repair Order Questionnaire below along with the print-out of
"Before" and "After" wheel alignment measurements to
the Repair Order and retain for use by GM.
Wheel Alignment Equipment and Process
Wheel alignments must be performed with a quality machine that will give accurate results when
performing checks. "External Reference" (image-based camera technology) is preferred. Please
refer to Corporate Bulletin Number 05-00-89-029B: General Motors Dealership Critical Equipment
Requirements and Recommendations.
Requirements:
- Computerized four wheel alignment system.
- Computer capable of printing before and after alignment reports.
- Computer capable of time and date stamp printout.
- Racking system must have jacking capability
- Racking system must be capable of level to 1.6 mm (1/16 in)
- Appropriate wheel stops and safety certification
- Built-in turn plates and slip plates
- Wheel clamps capable of attaching to 20" or larger wheels
- Racking capable of accepting any GM passenger car or light duty truck
- Operator properly trained and ASE-certified (U.S. only) in wheel alignment
Recommendations:
Racking should have front and rear jacking capability.
Equipment Maintenance and Calibration:
Alignment machines must be regularly calibrated in order to give correct information. Most
manufacturers recommend the following:
- Alignment machines with "internal reference" sensors should be checked (and calibrated, if
necessary) every six months.
- Alignment machines with "external reference" (image-based camera technology) should be
checked (and calibrated, if necessary) once a year.
- Racks must be kept level to within 1.6 mm (1/16 in).
- If any instrument that is part of the alignment machine is dropped or damaged in some way,
check the calibration immediately.
Check with the manufacturer of your specific equipment for their recommended service/calibration
schedule.
Wheel Alignment Process
When performing wheel alignment measurement and/or adjustment, the following steps should be
taken:
Preliminary Steps:
1. Verify that the vehicle has a full tank of fuel (compensate as necessary). 2. Inspect the wheels
and the tires for damage. 3. Inspect the tires for the proper inflation and irregular tire wear. 4.
Inspect the wheel bearings for excessive play. 5. Inspect all suspension and steering parts for
looseness, wear, or damage. 6. Inspect the steering wheel for excessive drag or poor return due to
stiff or rusted linkage or suspension components. 7. Inspect the vehicle trim height. 8. Compensate
for frame angle on targeted vehicles (refer to Wheel Alignment Specifications in SI).
Satisfactory vehicle operation may occur over a wide range of alignment angles. However, if the
wheel alignment angles are not within the range of specifications, adjust the wheel alignment to the
specifications. Refer to Wheel Alignment Specifications in SI. Give consideration to excess loads,
such as tool boxes, sample cases, etc. Follow the wheel alignment equipment manufacturer's
instructions.
Measure/Adjust:
Important Prior to making any adjustments to wheel alignment on a vehicle, technicians must verify
that the wheel alignment specifications loaded into their wheel alignment machine are up-to-date
by comparing these to the wheel alignment specifications for the appropriate model and model year
in SI. Using incorrect and/or outdated specifications may result in unnecessary adjustments,
irregular and/or premature tire wear and repeat customer concerns
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7462
Important When performing adjustments to vehicles requiring a 4-wheel alignment, set the rear
wheel alignment angles first in order to obtain proper front wheel alignment angles.
Perform the following steps in order to measure the front and rear alignment angles:
1. Install the alignment equipment according to the manufacturer's instructions. 2. Jounce the front
and the rear bumpers 3 times prior to checking the wheel alignment. 3. Measure the alignment
angles and record the readings.
If necessary, adjust the wheel alignment to vehicle specification and record the before and after
measurements. Refer to Wheel Alignment Specifications in SI.
Important Technicians must refer to SI for the correct wheel alignment specifications. SI is the only
source of GM wheel alignment specifications that is kept up-to-date throughout the year.
Test drive vehicle to ensure proper repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7463
Frame Angle Measurement (Express / Savana Only) ........
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7464
What corrected the customer concern and was the repair verified?
Please Explain: .............
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Technical Service Bulletins for Alignment: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening
Alignment: All Technical Service Bulletins Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Important:
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All Technical Service Bulletins for Alignment: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening >
Page 7469
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
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All Technical Service Bulletins for Alignment: > 533403 > May > 95 > Rear Wheel - Tire Position in Wheel Well Opening >
Page 7470
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications
Alignment: All Technical Service Bulletins Steering/Suspension - Wheel Alignment Specifications
WARRANTY ADMINISTRATION
Bulletin No.: 05-03-07-009C
Date: December 09, 2010
Subject: Wheel Alignment Specifications, Requirements and Recommendations for GM Vehicles
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks
Supercede: This bulletin is being extensively revised to provide technicians and warranty
administrators with an all inclusive guide for wheel alignments. PLEASE FAMILIARIZE YOURSELF
WITH THESE UPDATES BEFORE PERFORMING YOUR NEXT GM WHEEL ALIGNMENT
SERVICE. Please discard Corporate Bulletin Number 05-03-07-009B (Section 03 - Suspension).
Purpose
The purpose of this bulletin is to provide retail, wholesale and fleet personnel with General Motors'
warranty service requirements and recommendations for customer concerns related to wheel
alignment. For your convenience, this bulletin updates and centralizes all of GM's Standard Wheel
Alignment Service Procedures, Policy Guidelines and bulletins on wheel alignment warranty
service.
Important PLEASE FAMILIARIZE YOURSELF WITH THESE UPDATES BEFORE PERFORMING
YOUR NEXT GM WHEEL ALIGNMENT SERVICE.
The following five (5) key steps are a summary of this bulletin and are REQUIRED in completing a
successful wheel alignment service.
1. Verify the vehicle is in an Original Equipment condition for curb weight, tires, wheels, suspension
and steering configurations. Vehicles
modified in any of these areas are not covered for wheel alignment warranty.
2. Review the customer concern relative to "Normal Operation" definitions. 3. Verify that vehicle is
within the "Mileage Policy" range. 4. Document wheel alignment warranty claims appropriately for
labor operations E2000 and E2020.
The following information must be documented or attached to the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
5. Use the proper wheel alignment equipment (preferred with print-out capability), process and the
appropriate calibration maintenance schedules.
Important If it is determined that a wheel alignment is necessary under warranty, use the proper
labor code for the repair. E2000 for Steering Wheel Angle and/or Front Toe set or E2020 for Wheel
Alignment Check/Adjust includes Caster, Camber and Toe set (Wheel alignment labor time for
other component repairs is to be charged to the component that causes a wheel alignment
operation.).
The following flowchart is to help summarize the information detailed in this bulletin and should be
used whenever a wheel alignment is performed.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Verify Original Equipment Condition of the Vehicle
- Verify that Original Equipment Tires and Wheels or Official GM Accessory Tires and Wheels are
on the vehicle.
- Verify that aftermarket suspension "Lift" or "Lowering" Kits or other suspension alterations have
NOT been done to the vehicle.
- Check for accidental damage to the vehicle; for example, severe pothole or curb impacts, collision
damage that may have affected the wheel alignment of the vehicle; e.g., engine cradles,
suspension control arms, axles, wheels, wheel covers, tires may show evidence of damage/impact.
- Check to be sure vehicle has seen "Normal Use" rather than abuse; e.g., very aggressive driving
may show up by looking at the tires and condition of the vehicle.
- Check for other additional equipment items that may significantly affect vehicle mass such as
large tool boxes, campers, snow plow packages (without the snowplow RPO), etc., especially in
trucks and cutaway/incomplete vehicles. Significant additional mass can affect trim height and
wheel alignment of the vehicle and may necessitate a customer pay wheel alignment when placed
semi-permanently in the vehicle (Upfitter instructions are to realign the vehicle after placement of
these types of items. (This typically applies to trucks and incomplete vehicles that can be upfit with
equipment such as the above.)
Customer Concerns, "Normal Operation" Conditions and "Mileage Policy"
Possible Concerns
The following are typical conditions that may require wheel alignment warranty service:
1. Lead/Pull: defined as "at a constant highway speed on a typical straight road, the amount of
effort required at the steering wheel to maintain the
vehicle's straight heading."
Important Please evaluate for the condition with hands-on the steering wheel. Follow the "Vehicle
Leads/Pulls" diagnostic tree located in SI to determine the cause of a lead/pull concern. Lead/Pull
concerns can be due to road crown or road slope, tires, wheel alignment or even in rare
circumstances a steering gear issue. Lead/pull concerns due to road crown are considered
"Normal Operation" and are NOT a warrantable condition -- the customer should be advised that
this is "Normal Operation."
Important Some customers may comment on a "Lead/Pull" when they hold the steering wheel in a
level condition. If so, this is more likely a "steering wheel angle" concern because the customer is
"steering" the vehicle to obtain a "level" steering wheel.
2. Steering wheel angle to the left or right (counter-clockwise or clockwise, respectively): Defined
as the steering wheel angle (clocking)
deviation from "level" while maintaining a straight heading on a typical straight road.
3. Irregular or Premature tire wear: Slight to very slight "feathering" or "edge" wear on the
shoulders of tires is NOT considered unusual and
should even out with a tire rotation; if the customer is concerned about a "feathering" condition of
the tires, the customer could be advised to rotate the tires earlier than the next scheduled
mileage/maintenance interval (but no later than the next interval). Be sure to understand the
customer's driving habits as this will also heavily influence the tire wear performance; tire wear from
aggressive or abusive driving habits is NOT a warrantable condition.
Important Slight or mild feathering, cupping, edge or heel/toe wear of tire tread shoulders is
"normal" and can show up very early in a tire/vehicle service mileage; in fact, some new tires can
show evidence of feathering from the factory. These issues do NOT affect the overall performance
and tread life of the tire. Dealer personnel should always check the customer's maintenance
records to ensure that tire inflation pressure is being maintained to placard and that the tires are
being rotated (modified-X pattern) at the proper mileage intervals. Wheel alignments are NOT to be
performed for the types of "Normal" Tire Feathering shown in Figures 1-4 below.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7477
Figure 1: Full Tread View - "NORMAL" Tire "Feathering" Wear on the Shoulder/Adjacent/Center
Ribs
Figure 2: Tire Shoulder View Example 1 - "NORMAL" Tire "Feathering" Wear on the Shoulder
Figure 3: Tire Shoulder View Example 2 - "NORMAL" Tire "Feathering" Wear
Figure 4: Detail Side View of Tire Shoulder Area - "NORMAL" Tire "Feathering" Wear
Important When a wheel alignment is deemed necessary for tire wear, be sure to document on the
repair order, in as much detail as possible, the severity and type of tire wear (e.g., severe center
wear or severe inside or outside shoulder wear) and the position of the tire on the vehicle (RF, LF,
LR, RR). Please note the customer's concern with the wear such as, noise, appearance, wear life,
etc. A field product report with pictures of the tire wear condition is recommended. Refer to
Corporate Bulletin Number 02-00-89-002J and #07-00-89-036C.
4. Other repairs that affect wheel alignment; e.g., certain component replacement such as
suspension control arm replacement, engine cradle
adjustment/replace, steering gear replacement, steering tie rod replace, suspension strut/shock,
steering knuckle, etc. may require a wheel alignment.
Important If other components or repairs are identified as affecting the wheel alignment, policy calls
for the wheel alignment labor time to be charged to the replaced/repaired component's labor
operation time rather than the wheel alignment labor operations.
Important Vibration type customer concerns are generally NOT due to wheel alignment except in
the rare cases; e.g., extreme diagonal wear across the tread. In general, wheel alignments are
NOT to be performed as an investigation/correction for vibration concerns.
"Normal Operation" Conditions
Vehicle Lead/Pull Due to Road Crown or Slope:
As part of "Normal Operation," vehicles will follow side-to-side or left to right road crown or slope.
Be sure to verify from the customer the types of roads they are driving as they may not recognize
the influence of road crown on vehicle lead/pull and steering wheel angle. If a vehicle requires
significant steering effort to prevent it from "climbing" the road crown there may be an issue to be
looked into further.
Important
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Specifications > Page 7478
A wheel alignment will generally NOT correct vehicles that follow the road crown since this is within
"Normal Operation."
Mileage Policy
The following mileage policy applies for E2020 and E2000 labor operations: Note
Wheel Alignment is NOT covered under the New Vehicle Limited Warranty for Express and Savana
Cutaway vehicles as these vehicles require Upfitters to set the wheel alignment after completing
the vehicles.
- 0-800 km (0-500 mi): E2000/E2020 claims ONLY allowed with Call Center Authorization. Due to
the tie down during shipping, the vehicle's suspension requires some time to reach normal
operating position. For this reason, new vehicles are generally NOT to be aligned until they have
accumulated at least 800 km (500 mi). A field product report should accompany any claim within
this mileage range.
- 801-12,000 km (501-7,500 mi):
- If a vehicle came from the factory with incorrect alignment settings, any resulting off-angle
steering wheel, lead/pull characteristics or the rare occurrence of excessive tire wear would be
apparent early in the life of the vehicle. The following policy applies:
- Vehicles 100% Factory Set/Measured for Caster/Camber/Toe - Escalade/ESV/EXT,
Tahoe/Suburban, Yukon/XL/Denali, Silverado/Sierra, Express/Savana, Corvette and
Colorado/Canyon: E2000/E2020 Claims: Call Center Authorization Required
- All Vehicles NOT 100% Factory Set/Measured for Caster/Camber/Toe as noted above:
E2000/E2020 Claims: Dealer Service Manager Authorization Required
- 12,001 km and beyond (7,501 miles and beyond): During this period, customers are responsible
for the wheel alignment expense or dealers may provide on a case-by case basis a one-time
customer enthusiasm claim up to 16,000 km (10,000 mi). In the event that a defective component
required the use of the subject labor operations, the identified defective component labor operation
will include the appropriate labor time for a wheel alignment as an add condition to the component
repair.
Important Only one wheel alignment labor operation claim (E2000 or E2020) may be used per VIN.
Warranty Documentation Requirements
When a wheel alignment service has been deemed necessary, the following items will need to be
clearly documented on/with the repair order:
- Customer concern in detail
- What corrected the customer concern?
- If a wheel alignment is performed:
- Consult SI for proper specifications.
- Document the "Before" AND "After" wheel alignment measurements/settings.
- Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin)
1. Document the customer concern in as much detail as possible on the repair order and in the
warranty administration system. Preferred examples:
- Steering wheel is off angle in the counterclockwise direction by approximately x degrees or
clocking position.
- Vehicle lead/pulls to the right at approximately x-y mph. Vehicle will climb the road crown. Severe,
Moderate or Slight.
- RF and LF tires are wearing on the outside shoulders with severe feathering.
Important In the event of a lead/pull or steering wheel angle concern, please note the direction of
lead/pull (left or right) or direction of steering wheel angle (clockwise or counterclockwise) on the
repair order and within the warranty claim verbatim.
Important In the event of a tire wear concern, please note the position on the vehicle and where the
wear is occurring on the tire; i.e., the RF tire is wearing on the inside shoulder.
2. Document the technician's findings on cause and correction of the issue. Examples:
- Reset LF toe from 0.45 degrees to 0.10 degrees and RF toe from -0.25 degrees to 0.10 degrees
to correct the steering wheel angle from 5 degrees counterclockwise to 0 degrees.
- Reset LF camber from 0.25 degrees to -0.05 degrees to correct the cross-camber condition of
+0.30 degrees to 0.00 degrees on the vehicle.
- Front Sum toe was found to be 0.50 degrees, reset to 0.20 degrees.
3. Print-out the "Before" and "After" wheel alignment measurements/settings and attach them to the
Repair Order or if print-out capability is not
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7479
available, measurements may also be clearly and legibly handwritten into the Wheel Alignment
Repair Order Questionnaire attached to this bulletin.
4. Attach the Wheel Alignment Repair Order Questionnaire below along with the print-out of
"Before" and "After" wheel alignment measurements to
the Repair Order and retain for use by GM.
Wheel Alignment Equipment and Process
Wheel alignments must be performed with a quality machine that will give accurate results when
performing checks. "External Reference" (image-based camera technology) is preferred. Please
refer to Corporate Bulletin Number 05-00-89-029B: General Motors Dealership Critical Equipment
Requirements and Recommendations.
Requirements:
- Computerized four wheel alignment system.
- Computer capable of printing before and after alignment reports.
- Computer capable of time and date stamp printout.
- Racking system must have jacking capability
- Racking system must be capable of level to 1.6 mm (1/16 in)
- Appropriate wheel stops and safety certification
- Built-in turn plates and slip plates
- Wheel clamps capable of attaching to 20" or larger wheels
- Racking capable of accepting any GM passenger car or light duty truck
- Operator properly trained and ASE-certified (U.S. only) in wheel alignment
Recommendations:
Racking should have front and rear jacking capability.
Equipment Maintenance and Calibration:
Alignment machines must be regularly calibrated in order to give correct information. Most
manufacturers recommend the following:
- Alignment machines with "internal reference" sensors should be checked (and calibrated, if
necessary) every six months.
- Alignment machines with "external reference" (image-based camera technology) should be
checked (and calibrated, if necessary) once a year.
- Racks must be kept level to within 1.6 mm (1/16 in).
- If any instrument that is part of the alignment machine is dropped or damaged in some way,
check the calibration immediately.
Check with the manufacturer of your specific equipment for their recommended service/calibration
schedule.
Wheel Alignment Process
When performing wheel alignment measurement and/or adjustment, the following steps should be
taken:
Preliminary Steps:
1. Verify that the vehicle has a full tank of fuel (compensate as necessary). 2. Inspect the wheels
and the tires for damage. 3. Inspect the tires for the proper inflation and irregular tire wear. 4.
Inspect the wheel bearings for excessive play. 5. Inspect all suspension and steering parts for
looseness, wear, or damage. 6. Inspect the steering wheel for excessive drag or poor return due to
stiff or rusted linkage or suspension components. 7. Inspect the vehicle trim height. 8. Compensate
for frame angle on targeted vehicles (refer to Wheel Alignment Specifications in SI).
Satisfactory vehicle operation may occur over a wide range of alignment angles. However, if the
wheel alignment angles are not within the range of specifications, adjust the wheel alignment to the
specifications. Refer to Wheel Alignment Specifications in SI. Give consideration to excess loads,
such as tool boxes, sample cases, etc. Follow the wheel alignment equipment manufacturer's
instructions.
Measure/Adjust:
Important Prior to making any adjustments to wheel alignment on a vehicle, technicians must verify
that the wheel alignment specifications loaded into their wheel alignment machine are up-to-date
by comparing these to the wheel alignment specifications for the appropriate model and model year
in SI. Using incorrect and/or outdated specifications may result in unnecessary adjustments,
irregular and/or premature tire wear and repeat customer concerns
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7480
Important When performing adjustments to vehicles requiring a 4-wheel alignment, set the rear
wheel alignment angles first in order to obtain proper front wheel alignment angles.
Perform the following steps in order to measure the front and rear alignment angles:
1. Install the alignment equipment according to the manufacturer's instructions. 2. Jounce the front
and the rear bumpers 3 times prior to checking the wheel alignment. 3. Measure the alignment
angles and record the readings.
If necessary, adjust the wheel alignment to vehicle specification and record the before and after
measurements. Refer to Wheel Alignment Specifications in SI.
Important Technicians must refer to SI for the correct wheel alignment specifications. SI is the only
source of GM wheel alignment specifications that is kept up-to-date throughout the year.
Test drive vehicle to ensure proper repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7481
Frame Angle Measurement (Express / Savana Only) ........
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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All Other Service Bulletins for Alignment: > 05-03-07-009C > Dec > 10 > Steering/Suspension - Wheel Alignment
Specifications > Page 7482
What corrected the customer concern and was the repair verified?
Please Explain: .............
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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All Other Service Bulletins for Alignment: > Page 7483
Alignment: By Symptom
Technical Service Bulletin # 533403 Date: 950501
Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > Page 7484
Important:
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > Page 7485
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > Page 7486
Technical Service Bulletin # 533403 Date: 950501
Rear Wheel - Tire Position in Wheel Well Opening
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-34-03
DATE: May, 1995
SUBJECT: Rear Wheel/Tire Position in Wheel Well Opening (Elongate Axle Bracket Control Arm
Attaching Bolt Holes)
MODELS: 1994-95 Chevrolet Caprice/Impala SS
CONDITION
Some customers may comment that one rear wheel may appear more forward in wheel well
opening than wheel on opposite side of vehicle or that vehicle appears to dog track when viewed
from the rear when in operation.
CAUSE
Rear lower control arm frame bracket holes pierced off location during frame manufacturing.
CORRECTION
Elongate holes in rear axle control arm bracket per service procedure indicated below:
1. Raise vehicle and support rear axle to simulate curb height position (weight of vehicle on axle).
2. Using lower edge of sill plate as a guide for scale/ruler, measure distance from tire to wheel well
opening on both sides of vehicle (Reference Figure 1).
3. Subtract smaller dimension from larger one and refer to chart below to determine amount holes
of axle lower control arm bracket are to be elongated.
Side to Side Dimension Hole Elongation
Difference Amount
5 mm through 10 mm 4 mm
11 mm through 15 mm 6 mm
16 mm through 20 mm 8 mm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > Page 7487
Important:
Holes to be elongated in a forward direction are those on the rear axle lower control arm bracket,
on the side of the vehicle that had the smaller dimension measured in Step 2.
4. Disconnect and remove rear stabilizer shaft, if equipped.
5. Remove lower control arm to axle assembly attaching bolt and swing control arm downward on
side of axle determined in Step 3 to require hole elongation.
6. Cut out template along outer outline. Cut out hole in template indicated as original bracket hole.
(Reference Figure 5).
7. Position template on inboard surface of axle control arm bracket as shown in Figure 2. Align hole
in template with hole in bracket and insure bottom edge of template is parallel to bottom edge of
bracket.
8. Transfer from the template to the bracket the amount hole is to be elongated along axis indicated
on template.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Technical Service Bulletins >
All Other Service Bulletins for Alignment: > Page 7488
9. Position template on outboard surface of axle control arm bracket as shown in Figure 3. Align
hole in template with hole in bracket and insure bottom edge of template is parallel to bottom edge
of bracket.
10. Repeat step 8.
11. Using a die grinder or other suitable tool, elongate holes.
12. Swing lower control arm into position and install attaching bolt and nut as shown in Figure 4.
With axle assembly positioned as far rearward as elongated holes will allow, torque attaching bolt
to 190 Nm (140 lb.ft.) holding nut with a backup wrench.
13. Position and connect stabilizer shaft and torque attaching bolts to 85 Nm (63 lb.ft.).
14. Lower vehicle.
WARRANTY INFORMATION
For vehicles repaired under warranty, use:
Labor
Operation Labor Time
E5610 Use Published Labor Operation Time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Specifications > Vehicle Ride
(Trim) Height Specifications
Alignment: Specifications Vehicle Ride (Trim) Height Specifications
Fig. 4 Vehicle Ride Height Measurement Locations & Specifications
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Specifications > Vehicle Ride
(Trim) Height Specifications > Page 7491
Alignment: Specifications Alignment Specifications
Front Alignment Specifications
Caster Angle, Degrees
Limits ...................................................................................................................................................
....................................................................... [01] Desired .................................................................
....................................................................................................................................................... [03]
Camber Angle, Degrees
Limits ...................................................................................................................................................
................................................................ - 1 to +1 Desired .................................................................
........................................................................................................................................................... 0
Total Toe, Degrees ..............................................................................................................................
............................................................... -.04 to +.36
Ball Joint Wear, Inch
Lower Ball Stud [02] ............................................................................................................................
..................................................................... .050 Upper Ball Stud [02] ..............................................
................................................................................................................................................... .125
[01] Left side, +2.25 to +4.25; right side, +2.75 to +4.75.
[02] Refer to Suspension/Ball Joint, lower or Upper/Service and Repair for proper ball joint
inspection procedure.
[03] Left side, +3.25; right side, +3.75.
Rear Alignment Specifications
Thrust Angle, Degrees .........................................................................................................................
.............................................................. -.15 to +.15
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Service and Repair >
Preliminary Inspection
Alignment: Service and Repair Preliminary Inspection
1. Inspect tires for proper inflation and similar tread wear. 2. Inspect hub and bearing for excessive
wear, repair as required. 3. Inspect ball joints. 4. Inspect tie rod ends for excessive looseness. 5.
Check wheel and tire runout. 6. Inspect vehicle ride height. 7. Inspect rack and pinion for looseness
at frame. 8. Ensure proper strut operation. 9. Check suspension and steering components for
damage, replace as required.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Service and Repair >
Preliminary Inspection > Page 7494
Alignment: Service and Repair Ride/Trim Height Measurement and Adjustment
Fig. 4 Vehicle Ride Height Measurement Locations & Specifications
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Service and Repair >
Preliminary Inspection > Page 7495
Alignment: Service and Repair Front Wheel Alignment
Front Caster Adjustment
Fig. 1 Caster & Camber Adjustments
Caster adjustments are made by means of shims between the upper control arm inner support
shaft and the support bracket attached to the frame, Fig. 1. Shims may be added, subtracted or
transferred to change the readings. Transfer shims from front to rear or rear to front. The transfer of
one shim to the front bolt from the rear bolt will decrease positive caster. One shim (1/32 inch)
transferred from the rear bolt to the front bolt will change caster about 1/2 degree.
Front Camber Adjustment
Fig. 1 Caster & Camber Adjustments
Camber adjustments are made by means of shims between the upper control arm inner support
shaft and the support bracket attached to the frame, Fig. 1. Shims may be added, subtracted or
transferred to change the readings. Change shims at both the front and rear of the shaft. Adding an
equal number of shims at both front and rear of the support shaft will decrease positive camber.
One shim (1/32 inch) at each location will move camber approximately 1/6 degree.
Front Toe Adjustment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Alignment > System Information > Service and Repair >
Preliminary Inspection > Page 7496
Fig. 2 Toe-in Adjustment
Toe-in can be adjusted by loosening the clamp bolts at each end of each tie rod and turning each
tie rod to increase or decrease its length as necessary until proper toe-in is secured and the
steering gear is on the high point for straight-ahead driving, Fig. 2.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Relays and Modules - Steering and Suspension > Relays and
Modules - Steering > Steering Control Module > Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Relays and Modules - Steering and Suspension > Relays and
Modules - Steering > Steering Control Module > Component Information > Locations > Page 7502
Power Steering Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Relays and Modules - Steering and Suspension > Relays and
Modules - Suspension > Compressor/Pump Relay, Suspension Control > Component Information > Description and
Operation
Compressor/Pump Relay: Description and Operation
DESCRIPTION
The compressor relay is controlled by the height sensor and completes the 12-volt circuit to the
compressor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Sensors and Switches - Steering and Suspension > Sensors
and Switches - Steering > Power Steering Pressure Switch > Component Information > Locations
Left Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Sensors and Switches - Steering and Suspension > Sensors
and Switches - Steering > Power Steering Pressure Switch > Component Information > Diagrams > Diagram Information
and Instructions
Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Power Steering Pressure Switch Circuit.
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Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
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Center Of Rear Crossmember
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Ride Height Sensor: Description and Operation
DESCRIPTION
The height sensor controls two circuits, compressor relay coil ground circuit and exhaust solenoid
coil ground circuit. To prevent energizing the compressor relay and exhaust solenoid circuits during
normal ride motions, the sensor circuit provides a predetermined delay before the ground circuit is
completed. The sensor electronically limits compressor run time and exhaust solenoid energized
time. This limit function is necessary to prevent continuous compressor operation in case of a
system leak or continuous exhaust solenoid operation. This timer is reset whenever the ignition is
turned Off and On, or height sensor exhaust or compressor signal changes. The height sensor is
mounted to the body frame in the rear of the vehicle. The sensor actuator arm is attached to the
control arm by a short link
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Sensors and Switches - Steering and Suspension > Sensors
and Switches - Suspension > Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7552
Ride Height Sensor: Testing and Inspection
CAUTION: When diagnostic procedures require that vehicle be raised on a hoist, it is important that
the rear axle assembly remains in the normal trim height position at all times. When a frame
contact hoist is used, two additional jack stands should be used to support the rear axle or control
arms in the normal trim height position.
1. Turn ignition Off, then On. This will reset height sensor timer circuits.
2. Raise vehicle on hoist. Ensure rear wheels or axle housing are supported and that vehicle is at
proper trim height.
3. Disconnect link from height sensor arm, then ensure sensor wiring and harness ground are
connected properly.
4. Move sensor arm upward. There should be a delay of 8-15 seconds before compressor turns on
and shocks start to inflate. As soon as shocks start to fill, stop compressor by moving sensor arm
down.
5. Move sensor arm down below position where compressor stopped. There should be a delay of
8-15 seconds before shocks start to deflate and vehicle lowers.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Sensors and Switches - Steering and Suspension > Sensors
and Switches - Suspension > Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7553
Ride Height Sensor: Adjustments
ADJUSTMENTS
The link should be properly attached to the sensor arm and track bar, when making this
adjustment.
1. Loosen lock bolt securing metal arm to height sensor plastic arm. 2. To raise vehicle trim height,
move plastic arm upward and tighten lock bolt. 3. To lower vehicle trim height, loosen lock bolt
securing metal arm to height sensor plastic arm, then move plastic arm down. 4. If adjustment
cannot be made, check for correct sensor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Sensors and Switches - Steering and Suspension > Sensors
and Switches - Suspension > Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7554
Ride Height Sensor: Service and Repair
WARNING: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
1. Disconnect battery ground cable.
2. Raise and support vehicle.
3. Disconnect harness from sensor electrical connector by squeezing oval sides of the connector
lock to release locking tabs.
4. Remove link from height sensor arm, then remove sensor mounting screws or nuts and the
sensor.
5. Remove sensor mounting bracket to underbody attaching screws and remove bracket.
6. Reverse procedure to install, noting the following:
a. When connecting harness to sensor electrical connector, push connector into sensor plug until
sloped shoulder on rear edge of boss is visible
in plug slot. Push oval connector lock onto plug until its two locking tabs snap over shoulder of
sensor plug.
b. Perform height sensor operational check and adjustment procedure as described under Testing
and Inspection. See: Testing and Inspection
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Front Steering Knuckle > Component Information >
Technical Service Bulletins > Steering Knuckle Nuts - Revised Torque Specification
Front Steering Knuckle: Technical Service Bulletins Steering Knuckle Nuts - Revised Torque
Specification
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-33-02A
DATE: June, 1995
SUBJECT: Section 3C - Revised Torque Specification for Steering Knuckle Nuts (Upper and
Lower)
MODELS: 1993-95 Buick Roadmaster 1993-95 Cadillac Fleetwood 1993-95 Chevrolet Caprice
1994-95 Chevrolet Impala SS
The torque specification for upper and lower steering knuckle nuts should be as follows:
Tighten
^ Steering knuckle nut (upper) (1) to 83 Nm (61 lb.ft.), additional tightening may be required to
insert cotter pin (3). Do not exceed 60° additional
tightening.
^ Steering knuckle nut (lower) (2) to 112 Nm (63 lb.ft.), additional tightening may be required to
insert cotter pin (3). Do not exceed 60° additional
tightening.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Bleeding > System
Information > Service and Repair
Power Steering Bleeding: Service and Repair
Fig. 12 Power Steering System Bleed Procedure.
Bleed power steering system after any component replacement, disconnecting fluid line or in case
of steering system noise. Bleed system to prevent pump damage, stop steering noise and to
ensure proper system operation. Before bleeding, inspect steering system. Check and correct if
needed power steering lines touching frame body or engine. Also check all hose connections for
looseness or leaks and tighten.
Refer to Fig. 12 for proper bleeding procedure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Fluid Reservoir >
Component Information > Locations
Power Steering Fluid Reservoir: Locations
Engine Compartment
LH Front of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pressure Control
Valve > Component Information > Locations
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Locations
Component Location - Pictorial View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement
Power Steering Pump: Service and Repair Replacement
Fig. 14 Exploded View Of Power Steering Pump Mounting
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7575
Fig. 15 Power Steering Gear Inlet & Outlet Hose Locations
1. Siphon power steering fluid from reservoir to prevent excess spillage. 2. Drain engine cooling
system into suitable container(s), then, if equipped with mechanical fan, remove engine cooling fan
bracket. 3. Disconnect heater inlet and outlet hoses from water pump. 4. Remove heater inlet and
outlet hose clip bolt/screw from generator and power steering pump bracket, Fig. 14 then position
aside. 5. Remove drive belt from power steering pump. 6. Disconnect power steering gear inlet
hose from power steering pump, Fig. 15
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7576
7. Disconnect power steering fluid reservoir hose from power steering pump by squeezing clamp
and sliding away from pump, then rotating and
sliding hose away from power steering pump, Fig. 15
8. Remove pump bracket bolts/screws and generator bracket bolt/screw, then pump and pulley. 9.
Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7577
Power Steering Pump: Service and Repair Disassembly/Assembly
CB Series Pump
Fig. 5 Exploded View Of CB Series Power Steering Pump
Fig. 6 Return Tube Removal. CB Series Power Steering Pump
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7578
Fig. 7 Rotor And/Or Pump Ring Installation. CB Series Power Steering Pump
DISASSEMBLE
1. Disconnect battery ground cable, then remove power steering pump from vehicle. Refer to
individual car chapters for procedures. 2. Remove union fitting with O-ring and the O-ring seal, Fig.
5. 3. Remove control valve assembly and flow control spring. 4. Protect driveshaft with shim stock
and remove driveshaft seal by cutting with small chisel. Discard seal. 5. Remove return tube using
tap, nut and washers, Fig. 6, as follows. Plug return tube to prevent chips from entering pump.
a. Stack five 5/8 inch washers onto return tube. b. Run one 9/16 inch-12 nut midway up a 9/1 inch
12 tap. c. Install threaded end of tap into return tube until nut is positioned against washers. d.
Using wrench, hold top stationary while turning nut clockwise.
6. Remove end cover retaining ring by inserting punch in access hole. 7. Gently push on driveshaft
to assist in removing end cover, O-ring, pressure plate spring, pump ring, pump vanes and the
driveshaft subassembly,
consisting of pump rotor, thrust plate, driveshaft and shaft retaining ring.
8. Remove O-ring from housing. 9. Remove dowel pins, then the driveshaft seal if not previously
removed.
10. Remove pressure plate, pressure plate spring and O-ring from end cover. 11. Remove shaft
retaining ring from driveshaft, then the pump rotor and thrust plate.
INSPECTION
1. Clean all parts in power steering fluid, then dry thoroughly. 2. Inspect pump ring, vanes, thrust
plate, pressure plate and driveshaft for scoring, pitting or chatter marks, replacing parts as
necessary.
ASSEMBLE
1. Lubricate new driveshaft seal with power steering fluid and, using seal installer tool No. J 7728,
or equivalent, press driveshaft seal into pump
housing.
2. Install pump ring dowel pins into housing. 3. Install thrust plate and pump rotor onto driveshaft,
Fig. 7. 4. Install new shaft retaining ring onto driveshaft. 5. Install driveshaft subassembly into
housing. 6. Install pump ring with holes positioned correctly onto dowel pins, Fig. 7, in housing. 7.
Install vanes into pump rotor. 8. Lubricate new O-ring (large) with power steering fluid and install
O-ring into end cover. 9. Install pressure plate and pressure plate spring.
10. Lubricate new O-ring (small) and install O-ring into end cover.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7579
11. Lubricate outer edge of end cover with power steering fluid and press end cover into housing.
12. Insert retaining ring into groove in housing, with ring opening near access hole opening. 13.
Remove plug and any chips, then coat end of new return tube with Loctite solvent part No. 75559
and Loctite adhesive part No. 290, or
equivalents and press return tube into housing until bottomed.
P Series L/Reservoir Pump
Fig. 9 Power Steering Pump Assembly Overhaul (Part 1 Of 2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7580
Fig. 9 Power Steering Pump Assembly Overhaul (Part 2 Of 2)
Reverse Rotation Pump
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7581
Fig. 8 Power Steering Pump Assembly Overhaul. Reverse Rotation
DISASSEMBLE
1. Disconnect battery ground cable, then remove power steering pump from vehicle. Refer to
individual chassis chapter for procedure. 2. Remove retaining ring using punch in access hole, Fig.
8. 3. Remove internal components from pump assembly by gently pushing on driveshaft.
Components should include pressure plate and subassembly,
consisting of end cover, O-ring seal, pressure plate spring and pressure plate. Driveshaft
subassembly, consisting of pump rotor, thrust plate, driveshaft and shaft retaining ring.
4. Remove O-ring from pump housing. 5. Remove dowel pins and driveshaft seal. 6. Remove end
cover, pressure plate spring and O-ring from pressure plate. 7. Remove pump ring and vanes from
driveshaft subassembly, then shaft retaining rings from driveshaft.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7582
8. Remove thrust plate and pump rotor from driveshaft.
INSPECTION
1. Clean all parts in power steering fluid, then dry thoroughly. 2. Inspect pump ring, vanes, thrust
plate, pressure plate, rotor and driveshaft for scoring, pitting or chatter marks, replacing parts as
necessary.
ASSEMBLE
1. Lubricate new driveshaft seal with power steering fluid and, using seal installer tool No. J 7728,
or equivalent, press driveshaft seal into pump
housing.
2. Install pump ring dowel pins into housing. 3. Install thrust plate and pump rotor onto driveshaft. 4.
Install new shaft retaining ring onto driveshaft. 5. Install driveshaft subassembly into housing. 6.
Install vanes into pump rotor. 7. Install pump ring, with holes positioned correctly onto dowel pins in
housing. 8. Lubricate new O-ring with power steering fluid and install O-ring into groove in pump
housing. 9. Install pressure plate and pressure plate spring.
10. Lubricate new O-ring and install O-ring into end cover. 11. Lubricate outer edge of end cover
with power steering fluid and press end cover into housing. 12. Insert retaining ring into groove in
housing, with ring opening near access hole opening. 13. Remove plug and any chips, then coat
end of new return tube with Loctite solvent 75559 and Loctite 290 adhesive, or equivalents, and
press return
tube into housing until bottomed.
TC Series Pump
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7583
Fig. 11 Power Steering Pump Assembly Overhaul (Part 1 Of 4).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7584
Fig. 11 Power Steering Pump Assembly Overhaul (Part 2 Of 4).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7585
Fig. 11 Power Steering Pump Assembly Overhaul (Part 3 Of 4).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Power Steering Pump >
Component Information > Service and Repair > Replacement > Page 7586
Fig. 11 Power Steering Pump Assembly Overhaul (Part 4 Of 4).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Steering Control Module >
Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Power Steering > Steering Control Module >
Component Information > Locations > Page 7590
Power Steering Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Relays and Modules - Steering > Steering Control
Module > Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Relays and Modules - Steering > Steering Control
Module > Component Information > Locations > Page 7595
Power Steering Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Locations
Left Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions
Power Steering Pressure Switch: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7602
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7603
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7604
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7605
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7606
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7607
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7608
Power Steering Pressure Switch: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7609
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7610
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7624
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7625
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7626
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7627
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7628
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7629
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7630
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7631
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7632
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Diagram Information and Instructions > Page 7633
Power Steering Pressure Switch Circuit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Sensors and Switches - Steering > Power Steering
Pressure Switch > Component Information > Diagrams > Page 7634
Power Steering Pressure Switch: Description and Operation
This switch informs the PCM when the power steering pressure is high. During high pressure
conditions, the Powertrain Control Module (PCM) will increase idle speed to compensate for the
additional load. When the switch closes, the PCM will increase idle speed to compensate for the
additional load.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Column > Air Bag(s) Arming and Disarming
> System Information > Service and Repair > Air Bag Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Column > Air Bag(s) Arming and Disarming
> System Information > Service and Repair > Air Bag Disarming and Arming > Page 7640
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > Customer Interest: > 233208A > Aug > 96 > Steering - Crunch/Pop Noise
Steering Gear: Customer Interest Steering - Crunch/Pop Noise
File In Section: 3 - Steering/Suspension
Bulletin No.: 23-32-08A
Date: August, 1996
Subject: Steering System Crunch/Pop Noise (Apply Grease/Enlarge Attaching Holes)
Models: 1992-96 Buick Roadmaster 1992-93 Cadillac Fleetwood Brougham 1994-96 Cadillac
Fleetwood 1992-96 Chevrolet Caprice 1994-96 Chevrolet Impala SS 1992 Oldsmobile Custom
Cruiser
This bulletin is being revised to add the 1996 model year. Please discard Corporate Bulletin
Number 23-32-08 (Section 3 - Steering/Suspension).
Condition
Some vehicles may exhibit a steering related crunch and/or pop type noise apparent during low
speed turning maneuvers. These conditions can be differentiated from one another not only by the
type of noise, but also by when they are generated as indicated below.
A. Crunch Noise - May occur only when vehicle is in a full right or left hand turning maneuver.
B. Pop Noise - May occur anytime vehicle steering wheel is moved off center in either direction.
Cause
A. Crunch Noise - Movement of lower control arm steering stop on steering knuckle during full turn
type maneuvers.
B. Pop Noise - Slight movement between steering gear bolt threads and frame rail inboard steering
gear attaching holes.
Correction
Crunch Noise - Apply a thin film (approximately 1 mm thick) of high temperature water resistant
grease, P/N 12345996 (1.75 oz. tube), to the contacting surfaces of both the steering stops and
steering knuckles.
Pop Noise - Follow procedure below and enlarge the frame-rail inboard steering gear attaching
holes that show any contact with bolt threads.
1. Disconnect and remove air cleaner snorkle.
2. Disconnect intermediate steering shaft coupling shield and slide rearward.
3. Remove nut securing ABS module bracket to steering gear.
4. Raise vehicle.
Notice:
Ensure that the vehicle's wheels are pointing straight ahead and the steering wheel is in "LOCK"
position. Failure to do so may cause the steering wheel to rotate, causing damage to the coil
assembly.
5. Remove left front wheel and tire assembly.
6. Remove flexible coupling bolt and disengage coupling from steering gear.
7. Remove three (3) steering gear to frame rail attaching bolts and position gear away from frame
rail.
8. Inspect inboard frame rail steering gear attaching holes for any indication of bolt thread contact.
9. Carefully enlarge those holes that show bolt thread contact utilizing a rat-tail mill file.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > Customer Interest: > 233208A > Aug > 96 > Steering - Crunch/Pop Noise > Page 7649
10. Position steering gear to frame rail and hand start attaching bolts. Torque attaching bolts in
sequence # 1, # 2 and # 3 to 95 N.m (70 lb ft) as shown in illustration.
11. Connect flexible coupling to steering gear, install bolt and torque to 31 N.m (23 lb ft).
Notice:
Ensure that vehicle wheels are pointing straight ahead prior to connecting flexible coupling.
12. Install wheel and tire assembly and torque wheel nuts to 135 N.m (100 lb ft).
13. Lower vehicle.
14. Slide coupling shield forward and secure in position.
15. Install ABS module bracket nut and torque to 60 N.m (44 lb ft).
16. Install and connect air cleaner snorkle.
17. Start vehicle and cycle the steering lock to lock several times.
18. Loosen but do not remove attaching bolts # 1 and # 2, start vehicle and cycle the steering lock
to lock several times.
19. Torque attaching bolt # 2 and then # 1 to 95 N.m (70 lb ft).
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Labor Operation Labor Time
(A) E7001 (A) 0.3 hr
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > Customer Interest: > 233208A > Aug > 96 > Steering - Crunch/Pop Noise > Page 7650
(B) E7002 (B) 0.8 hr
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Steering Gear: > 83-32-10 > Nov > 98 > Tools - Adjuster Locknut
Wrench
Steering Gear: All Technical Service Bulletins Tools - Adjuster Locknut Wrench
File In Section: 3 - Steering/Suspension
Bulletin No.: 83-32-10
Date: November, 1998
INFORMATION
Subject: Essential Tool J 43435 Adjuster Locknut Wrench
Models: 1990-99 Passenger Cars and Trucks with Integral Power Steering
A new essential tool, J 43435 Adjuster Locknut Wrench, has been sent to all GM Dealers. This tool
should be used on all Integral power steering gears, both past and current models.
The following procedure should be used In place of existing Service Manual procedures for
Coupling Shield and Locknut Removal and Replacement. The correct adjustment procedure and
use of the essential tools are critical to restore the vehicle "On Center" feel (See Figure 1).
Important:
Coupling shield retainer and locknut assembly replacement procedures require the following
special tools:
J 42882 Adjuster Nut Wrench J 43435 Adjuster Locknut Wrench
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Steering Gear: > 83-32-10 > Nov > 98 > Tools - Adjuster Locknut
Wrench > Page 7656
(See Figure 2)
Procedure
1. Place J 42882 over the end of the stub shaft. Place J 43435 over the end. J 43435 is reversible
and can be used with both old and new style coupling shield retainers and locknuts.
2. Tighten the coupling shield retainer and locknut assembly after an adjustment or repair has been
made to the power steering gear to the specified torque (See Figure 3).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Steering Gear: > 233208A > Aug > 96 > Steering - Crunch/Pop Noise
Steering Gear: All Technical Service Bulletins Steering - Crunch/Pop Noise
File In Section: 3 - Steering/Suspension
Bulletin No.: 23-32-08A
Date: August, 1996
Subject: Steering System Crunch/Pop Noise (Apply Grease/Enlarge Attaching Holes)
Models: 1992-96 Buick Roadmaster 1992-93 Cadillac Fleetwood Brougham 1994-96 Cadillac
Fleetwood 1992-96 Chevrolet Caprice 1994-96 Chevrolet Impala SS 1992 Oldsmobile Custom
Cruiser
This bulletin is being revised to add the 1996 model year. Please discard Corporate Bulletin
Number 23-32-08 (Section 3 - Steering/Suspension).
Condition
Some vehicles may exhibit a steering related crunch and/or pop type noise apparent during low
speed turning maneuvers. These conditions can be differentiated from one another not only by the
type of noise, but also by when they are generated as indicated below.
A. Crunch Noise - May occur only when vehicle is in a full right or left hand turning maneuver.
B. Pop Noise - May occur anytime vehicle steering wheel is moved off center in either direction.
Cause
A. Crunch Noise - Movement of lower control arm steering stop on steering knuckle during full turn
type maneuvers.
B. Pop Noise - Slight movement between steering gear bolt threads and frame rail inboard steering
gear attaching holes.
Correction
Crunch Noise - Apply a thin film (approximately 1 mm thick) of high temperature water resistant
grease, P/N 12345996 (1.75 oz. tube), to the contacting surfaces of both the steering stops and
steering knuckles.
Pop Noise - Follow procedure below and enlarge the frame-rail inboard steering gear attaching
holes that show any contact with bolt threads.
1. Disconnect and remove air cleaner snorkle.
2. Disconnect intermediate steering shaft coupling shield and slide rearward.
3. Remove nut securing ABS module bracket to steering gear.
4. Raise vehicle.
Notice:
Ensure that the vehicle's wheels are pointing straight ahead and the steering wheel is in "LOCK"
position. Failure to do so may cause the steering wheel to rotate, causing damage to the coil
assembly.
5. Remove left front wheel and tire assembly.
6. Remove flexible coupling bolt and disengage coupling from steering gear.
7. Remove three (3) steering gear to frame rail attaching bolts and position gear away from frame
rail.
8. Inspect inboard frame rail steering gear attaching holes for any indication of bolt thread contact.
9. Carefully enlarge those holes that show bolt thread contact utilizing a rat-tail mill file.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Steering Gear: > 233208A > Aug > 96 > Steering - Crunch/Pop Noise
> Page 7661
10. Position steering gear to frame rail and hand start attaching bolts. Torque attaching bolts in
sequence # 1, # 2 and # 3 to 95 N.m (70 lb ft) as shown in illustration.
11. Connect flexible coupling to steering gear, install bolt and torque to 31 N.m (23 lb ft).
Notice:
Ensure that vehicle wheels are pointing straight ahead prior to connecting flexible coupling.
12. Install wheel and tire assembly and torque wheel nuts to 135 N.m (100 lb ft).
13. Lower vehicle.
14. Slide coupling shield forward and secure in position.
15. Install ABS module bracket nut and torque to 60 N.m (44 lb ft).
16. Install and connect air cleaner snorkle.
17. Start vehicle and cycle the steering lock to lock several times.
18. Loosen but do not remove attaching bolts # 1 and # 2, start vehicle and cycle the steering lock
to lock several times.
19. Torque attaching bolt # 2 and then # 1 to 95 N.m (70 lb ft).
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Labor Operation Labor Time
(A) E7001 (A) 0.3 hr
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Steering Gear: > 233208A > Aug > 96 > Steering - Crunch/Pop Noise
> Page 7662
(B) E7002 (B) 0.8 hr
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Steering Gear: > 83-32-10 > Nov > 98 > Tools - Adjuster Locknut Wrench
Steering Gear: All Technical Service Bulletins Tools - Adjuster Locknut Wrench
File In Section: 3 - Steering/Suspension
Bulletin No.: 83-32-10
Date: November, 1998
INFORMATION
Subject: Essential Tool J 43435 Adjuster Locknut Wrench
Models: 1990-99 Passenger Cars and Trucks with Integral Power Steering
A new essential tool, J 43435 Adjuster Locknut Wrench, has been sent to all GM Dealers. This tool
should be used on all Integral power steering gears, both past and current models.
The following procedure should be used In place of existing Service Manual procedures for
Coupling Shield and Locknut Removal and Replacement. The correct adjustment procedure and
use of the essential tools are critical to restore the vehicle "On Center" feel (See Figure 1).
Important:
Coupling shield retainer and locknut assembly replacement procedures require the following
special tools:
J 42882 Adjuster Nut Wrench J 43435 Adjuster Locknut Wrench
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > All Other Service Bulletins for Steering Gear: > 83-32-10 > Nov > 98 > Tools - Adjuster Locknut Wrench
> Page 7668
(See Figure 2)
Procedure
1. Place J 42882 over the end of the stub shaft. Place J 43435 over the end. J 43435 is reversible
and can be used with both old and new style coupling shield retainers and locknuts.
2. Tighten the coupling shield retainer and locknut assembly after an adjustment or repair has been
made to the power steering gear to the specified torque (See Figure 3).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Technical
Service Bulletins > Page 7669
Steering Gear: Specifications
Component ..........................................................................................................................................
....................................................... Torque/Ft. Lbs.
Adjuster Plug Locknut ..........................................................................................................................
............................................................................. 80 Pinion Preload [01] ...........................................
..............................................................................................................................................................
6-10 Rack & Pinion Guide Clamp [01] Screw ......................................................................................
..................................................................................... 43 Rack Piston Plug ......................................
..............................................................................................................................................................
.......... 111 Steering Gear Adjuster Locknut ........................................................................................
................................................................................................. 36
[01] Inch lbs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information >
Adjustments > Pitman Shaft Over-Center Preload
Steering Gear: Adjustments Pitman Shaft Over-Center Preload
Fig. 11 Stub Shaft Alignment
Fig. 12 Pitman Shaft Master Spline Alignment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information >
Adjustments > Pitman Shaft Over-Center Preload > Page 7672
Fig. 13 Overcenter Rotational Torque Inspection
1. Rotate stub shaft back and forth to drain fluid. 2. Turn pitman shaft adjuster screw
counterclockwise until fully extended, then turn back one full turn, Fig. 11. 3. Rotate stub shaft from
stop to stop and count the turns. 4. Starting at either stop, turn the stub shaft back one-half the total
number of turns. 5. When the gear is centered, the flat on stub shaft should face upward and be
parallel with side cover and master spline on pitman shaft should be
inline with adjuster screw, Fig. 12.
6. Rotate stub shaft 45 ° each side of center using a torque wrench with handle in vertical position,
Fig. 13, record the highest drag torque measured
on or near center.
7. Adjust overcenter drag torque by loosening adjuster locknut and turning the pitman shaft
adjuster screw clockwise until correct drag tightness is
obtained. On new steering gears (under 400 miles) add 5-11 inch lbs. to previously measured
worm bearing preload. Do not exceed total preload of 18 inch lbs. On used steering gears (400
miles or more) add 4-5 inch lbs. to previously measured worm bearing preload. Do not exceed total
gear preload of 13 inch lbs.
8. Hold adjuster screw and torque adjuster locknut to 22 ft. lbs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information >
Adjustments > Pitman Shaft Over-Center Preload > Page 7673
Steering Gear: Adjustments Steering Gear Adjustment
Adjustment of steering gear in the vehicle is not recommended because of the difficulty
encountered in adjusting the worm thrust bearing preload and confirming the effects of the
hydraulic fluid in the gear. Since a gear adjustment is made only as a correction and not a periodic
adjustment, it is better to take the extra time and make the adjustment correctly the first time.
Since a handling stability complaint can be caused by improperly adjusted worm thrust bearings as
well as an improper gear overcenter adjustment, it is necessary that the steering gear assembly be
removed from vehicle and both thrust bearing and overcenter preload be checked and corrected as
necessary. An in-vehicle check of steering gear will not show a thrust bearing adjustment error.
Valve assembly and seal drag should be 1-4 inch lbs. Thrust bearing preload should be 3-4 inch
lbs. in excess of valve assembly and seal drag.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Service
and Repair > Power Steering Gear
Steering Gear: Service and Repair Power Steering Gear
Fig. 13 Power Steering Gear Mount
1. Disconnect battery ground cable. 2. Disconnect pressure and return hoses from power steering
gear. Position hoses in upward direction to prevent fluid drainage. Cap lines and
fittings.
3. Disconnect intermediate steering shaft from steering gear stub shaft. 4. Disconnect Pitman arm
from steering gear. 5. On models equipped with ABS brake systems, remove ABS modulator
bracket attaching nut from steering gear. 6. On all models, remove steering attaching bolts and
washers, then remove steering gear, Fig. 13 7. Reverse procedure to install. Tighten attaching
bolts to specifications.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Service
and Repair > Power Steering Gear > Page 7676
Steering Gear: Service and Repair Saginaw Rotary Valve Type Power Steering Gears
Fig. 9 Exploded View Of Saginaw Rotary Valve Power Steering Gear
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Service
and Repair > Power Steering Gear > Page 7677
Fig. 10 Service Procedures (Part 1 Of 4) Saginaw Rotary Valve Power Steering Gear
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Service
and Repair > Power Steering Gear > Page 7678
Fig. 10 Service Procedures (Part 2 Of 4) Saginaw Rotary Valve Power Steering Gear
Component Service
Whenever a part which forms a sealing surface for an O-ring is removed, the O-ring seal should
also be removed and replaced with a new seal. Whenever one of the Pitman shaft or stub shaft
seals are removed, all adjacent seals should be removed and replaced with new seals. Lubricate
all new seals with power steering fluid to facilitate assembly. For service procedures on this power
steering gear assembly, refer to Figs. 9 and 10.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Service
and Repair > Power Steering Gear > Page 7679
Fig. 10 Service Procedures (Part 3 Of 4) Saginaw Rotary Valve Power Steering Gear
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Gear > Component Information > Service
and Repair > Power Steering Gear > Page 7680
Fig. 10 Service Procedures (Part 4 Of 4) Saginaw Rotary Valve Power Steering Gear
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Steering > Steering Wheel > Component Information > Service
and Repair
Steering Wheel: Service and Repair
Fig. 14 Steering Wheel With Air Bag
Mark position of steering wheel in relation to shaft prior to removal to ensure correct installation.
1. Disconnect battery ground cable. 2. Using a No. 30 Torx driver, loosen air bag inflator module
attaching screws until module can be released from steering wheel, Fig. 14. 3. Pull module
rearward, then disconnect coil, connector position assurance and horn lead connectors, then
remove module. Do not carry module
by connectors or wires, when placing live module on bench, place bag and trim cover upward.
4. Remove steering wheel attaching nut. 5. Using suitable steering wheel puller, remove steering
wheel and horn contact. 6. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Axle Beam > Component Information >
Description and Operation
Axle Beam: Description and Operation
In these rear axles, the rear axle housing and differential carrier are cast into an integral housing
assembly. The drive pinion assembly is mounted in two opposed tapered roller bearings. The
pinion bearings are preloaded by a spacer behind the front bearing. The pinion is positioned by a
washer between the head of the pinion and the rear bearing. The differential is supported in the
carrier by two tapered roller side bearings. These bearings are preloaded by spacers located
between the bearings and carrier housing. The differential assembly is positioned for proper ring
gear and pinion backlash by varying these spacers. The differential case houses two side gears in
mesh with two pinions mounted on a pinion shaft which is held in place by a lockpin. The side
gears and pinions are backed by thrust washers. A limited slip rear axle, available on most models,
uses disc or cone type clutches which are splined to the side gears to lock the axle shafts to the
case or in effect to each other. Therefore, if one drive wheel is on a slippery surface, the other
wheel must develop more torque than on a standard type differential before the differential case will
allow wheel spin. However, axle shaft torques produced during cornering are sufficient to overcome
the clutch action, allowing axles to rotate at different speeds.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Axle Beam > Component Information > Service
and Repair > Rear Axle
Axle Beam: Service and Repair Rear Axle
Construction of the axle assembly is such that service operations may be performed with the
housing installed in the vehicle or with the housing removed and installed in a holding fixture.The
following procedure is necessary only when the housing requires replacement.
1. Raise and support vehicle, then support rear axle with a suitable jack. 2. On models equipped
with anti-lock brake systems, remove rear axle speed sensor as follows:
a. Disconnect speed sensor electrical harness. b. Remove speed sensor harness bracket attaching
bolt. c. Remove speed sensor to rear axle attaching bolt, then remove speed sensor and bracket
assembly and position aside.
3. On all models, disconnect shock absorbers from lower mountings. 4. Remove propeller shaft. 5.
Disconnect upper control arms from axle housing attachments. 6. Disconnect brake line from axle
housing junction block and parking brake cable. 7. Disconnect lower control arms from axle
housing attachments. 8. Lower axle slowly until springs can be moved. Roll axle assembly out from
under vehicle. 9. Reverse procedure to install, noting the following:
a. Install anti-lock brake system wheel speed sensors by hand. Do not hammer sensors into
position as damage may result.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Axle Beam > Component Information > Service
and Repair > Rear Axle > Page 7690
Axle Beam: Service and Repair Rear Axle Shaft
Fig. 1 Pinion Shaft Lock Bolt & C-lock Removal
1. Raise vehicle and remove wheel and brake drum or rotor. 2. Drain lube from carrier and remove
cover. 3. Remove differential pinion shaft lock bolt and remove differential pinion shaft, Fig. 1, 4.
Pull flanged end of axle shaft toward center of vehicle and remove C-lock from button end of shaft.
5. Remove axle shaft from housing, being careful not to damage seal. 6. Reverse procedure to
install axle shaft.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Technical
Service Bulletins > Recalls for Ball Joint: > 96C14A > Apr > 96 > Recall - Lower Control Arm Ball Joint (Supplement)
Technical Service Bulletin # 96C14A Date: 960401
Recall - Lower Control Arm Ball Joint (Supplement)
CHEVROLET No.: 96-C-14A
Date: 04-01-96
Subject: PRODUCT SAFETY CAMPAIGN 96-C-14(a) - LOWER CONTROL ARM BALL JOINT
--- Supplement --Model and Year: 1995 -96 CHEVROLET CAPRICE/IMPALA POLICE SEDANS (SEO 9C1), TAXI
CAB (SEO 9C6) AND SPECIAL SERVICE WAGON (SEO lA2) AND RETAIL UNITS
To: All Chevrolet Dealers
This bulletin supplements Product Safety Campaign 96-C-14 issued February, 1996. Specifically,
the Vehicles Involved section has been revised to reflect the additional of retail (non-police/taxi)
passenger units and the Service Procedure has been revised to reflect a final ball joint nut torque
range. Additionally, a revised owner letter is attached. The revised information is printed in bold
type. This supplement should be filed with your campaign materials.
Vehicles Involved
Involved are certain 1995-96 Chevrolet Caprice/Impala Police Sedans, Taxi Cabs, Special Service
Wagons and Retail Passenger vehicles (sedans & wagons) built within the VIN breakpoints as
shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
SUPPLEMENTAL computer listings for retail units contain the complete Vehicle Identification
Number, owner name and address data, and are furnished to involved dealers with the campaign
bulletin. Owner name and address data furnished will enable dealers to follow-up with owners
involved in this campaign.
These listings may contain owner name and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with the
campaign bulletin has no involved vehicles currently assigned.
Service Procedure
INSPECTION - NUT TORQUE (To Be Performed On Both Sides)
3. Utilizing a clicker type torque wrench set at 60 Nm (44 lb. ft.) and while attempting to tighten
lower ball stud nut, determine which of the following conditions exists and proceed as required:
A.) Torque Wrench Clicks Prior To Nut Rotation [Nut torqued to more than 60 Nm (44 lb. ft.) as
installed]
I. Reset torque wrench to between 95 Nm (70 lb. ft.) to 112 Nm (83 lb. ft.) Tighten ball joint nut until
wrench clicks.
8. NO GAP: (Ball stud IS NOT seated in knuckle)
Replace knuckle and lower ball stud following applicable Service Manual Procedure, Section 3C-3,
Front suspension. Check and adjust wheel alignment and toe-in after new knuckle and lower ball
stud is installed. Proceed to Step 10.
OR
GAP: (Ball stud is seated in knuckle)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Technical
Service Bulletins > Recalls for Ball Joint: > 96C14A > Apr > 96 > Recall - Lower Control Arm Ball Joint (Supplement) > Page
7699
Tighten nut and torque to between 95 Nm (70 lb. ft.) to 112 Nm (83 lb. ft.), then tighten nut enough
to align slot in nut with hole in ball stud and install new cotter pin. Nut rotation to align cotter pin
hole is not to exceed one flat (60 degrees).
Owner Letter
Dear Chevrolet Caprice/Impala Owner:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that a defect which relates to motor vehicle safety exists in some
1995-96 Chevrolet Caprice/Impala vehicles. The lower control arm ball joint attachment nut may be
loose. This condition can cause the lower control arm ball joint to loosen, fatigue and separate from
the front suspension knuckle. If separation were to occur with the vehicle in motion, loss of vehicle
control may occur which could result in a vehicle crash without prior warning.
WHAT WE WILL DO
To correct this condition, all involved vehicles will have both front lower control arm ball joint
attachment nuts inspected for proper torque. If the ball joint has loosened from the knuckle, both
the ball joint and knuckle will be replaced. This service will be performed for you at no charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date and so they
may inspect your vehicle and if necessary order the necessary parts for the repair. Instructions for
making this correction have been sent to your dealer and parts are available. The labor time
necessary to perform this inspection/service correction is approximately 20 minutes to 3-1/2 hours.
Please ask your dealer if you wish to know how much additional time will be needed to schedule
and process your vehicle.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the Administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your safety and continue satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Ball Joint: > 96C14A > Apr > 96 > Recall - Lower Control Arm Ball
Joint (Supplement)
Technical Service Bulletin # 96C14A Date: 960401
Recall - Lower Control Arm Ball Joint (Supplement)
CHEVROLET No.: 96-C-14A
Date: 04-01-96
Subject: PRODUCT SAFETY CAMPAIGN 96-C-14(a) - LOWER CONTROL ARM BALL JOINT
--- Supplement --Model and Year: 1995 -96 CHEVROLET CAPRICE/IMPALA POLICE SEDANS (SEO 9C1), TAXI
CAB (SEO 9C6) AND SPECIAL SERVICE WAGON (SEO lA2) AND RETAIL UNITS
To: All Chevrolet Dealers
This bulletin supplements Product Safety Campaign 96-C-14 issued February, 1996. Specifically,
the Vehicles Involved section has been revised to reflect the additional of retail (non-police/taxi)
passenger units and the Service Procedure has been revised to reflect a final ball joint nut torque
range. Additionally, a revised owner letter is attached. The revised information is printed in bold
type. This supplement should be filed with your campaign materials.
Vehicles Involved
Involved are certain 1995-96 Chevrolet Caprice/Impala Police Sedans, Taxi Cabs, Special Service
Wagons and Retail Passenger vehicles (sedans & wagons) built within the VIN breakpoints as
shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
SUPPLEMENTAL computer listings for retail units contain the complete Vehicle Identification
Number, owner name and address data, and are furnished to involved dealers with the campaign
bulletin. Owner name and address data furnished will enable dealers to follow-up with owners
involved in this campaign.
These listings may contain owner name and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with the
campaign bulletin has no involved vehicles currently assigned.
Service Procedure
INSPECTION - NUT TORQUE (To Be Performed On Both Sides)
3. Utilizing a clicker type torque wrench set at 60 Nm (44 lb. ft.) and while attempting to tighten
lower ball stud nut, determine which of the following conditions exists and proceed as required:
A.) Torque Wrench Clicks Prior To Nut Rotation [Nut torqued to more than 60 Nm (44 lb. ft.) as
installed]
I. Reset torque wrench to between 95 Nm (70 lb. ft.) to 112 Nm (83 lb. ft.) Tighten ball joint nut until
wrench clicks.
8. NO GAP: (Ball stud IS NOT seated in knuckle)
Replace knuckle and lower ball stud following applicable Service Manual Procedure, Section 3C-3,
Front suspension. Check and adjust wheel alignment and toe-in after new knuckle and lower ball
stud is installed. Proceed to Step 10.
OR
GAP: (Ball stud is seated in knuckle)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Ball Joint: > 96C14A > Apr > 96 > Recall - Lower Control Arm Ball
Joint (Supplement) > Page 7705
Tighten nut and torque to between 95 Nm (70 lb. ft.) to 112 Nm (83 lb. ft.), then tighten nut enough
to align slot in nut with hole in ball stud and install new cotter pin. Nut rotation to align cotter pin
hole is not to exceed one flat (60 degrees).
Owner Letter
Dear Chevrolet Caprice/Impala Owner:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that a defect which relates to motor vehicle safety exists in some
1995-96 Chevrolet Caprice/Impala vehicles. The lower control arm ball joint attachment nut may be
loose. This condition can cause the lower control arm ball joint to loosen, fatigue and separate from
the front suspension knuckle. If separation were to occur with the vehicle in motion, loss of vehicle
control may occur which could result in a vehicle crash without prior warning.
WHAT WE WILL DO
To correct this condition, all involved vehicles will have both front lower control arm ball joint
attachment nuts inspected for proper torque. If the ball joint has loosened from the knuckle, both
the ball joint and knuckle will be replaced. This service will be performed for you at no charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date and so they
may inspect your vehicle and if necessary order the necessary parts for the repair. Instructions for
making this correction have been sent to your dealer and parts are available. The labor time
necessary to perform this inspection/service correction is approximately 20 minutes to 3-1/2 hours.
Please ask your dealer if you wish to know how much additional time will be needed to schedule
and process your vehicle.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the Administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your safety and continue satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Technical
Service Bulletins > Page 7706
Ball Joint: Testing and Inspection
Fig. 4 Upper Ball Joint Wear Inspection
1. Raise and support vehicle. Position jack stands under lower control arm as close to lower ball
joint as possible. 2. Position a suitable dial indicator against wheel rim, Fig. 4 3. Grasp wheel at top
and bottom, then pull top of wheel outward, while pushing inward on bottom of wheel. Note dial
indicator reading. 4. Pull bottom of wheel outward, while pushing inward on top of wheel. Note dial
indicator reading. 5. Deflection reading on dial indicator should not exceed .125 inch. 6. If reading
exceeds .125 inch, replace upper ball joint.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Service
and Repair > Upper Ball Joint Replacement
Ball Joint: Service and Repair Upper Ball Joint Replacement
Fig. 6 Upper Ball Joint Separation From Steering Knuckle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Service
and Repair > Upper Ball Joint Replacement > Page 7709
Fig. 7 Upper Ball Joint Installation
1. Raise vehicle and support with stands at outer ends of lower control arms. 2. Remove wheel and
tire. 3. Remove cotter pin and retaining nut, then separate ball joint stud from knuckle using a
suitable tool, Fig. 6. 4. Support upper control arm in a raised position. 5. Remove heads of rivets
securing joint to arm, then drive out rivets to remove joint. 6. Position replacement joint on top of
control arm, insert retaining bolts supplied with joint from under arm, install nuts and tighten to
specifications,
Fig. 7.
7. Remove upper control arm support, assemble ball joint to steering knuckle, install washer, if
equipped, and retaining nut. 8. Tighten retaining nut to specifications. 9. Tighten retaining nut up to
an additional 1/16 turn, if necessary, to align hole in ball stud with nut, then install cotter pin.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Service
and Repair > Upper Ball Joint Replacement > Page 7710
Ball Joint: Service and Repair Lower Ball Joint Replacement
Fig. 8 Lower Ball Joint Separation From Steering Knuckle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Service
and Repair > Upper Ball Joint Replacement > Page 7711
Fig. 9 Lower Ball Joint Removal From Lower Control Arm
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Ball Joint > Component Information > Service
and Repair > Upper Ball Joint Replacement > Page 7712
Fig. 10 Lower Ball Joint Installation Into Lower Control Arm
1. Raise vehicle and support at frame, and remove wheel and tire. 2. Position a suitable jack under
lower control arm spring seat, and raise jack to compress coil spring. Jack must remain in place
during ball joint
replacement to hold spring and lower control arm in position.
3. Remove cotter pin and nut securing ball joint stud to steering knuckle, then disconnect joint from
knuckle using a suitable tool, Fig. 8. 4. Lift knuckle assembly from ball stud, guiding control arm out
of splash shield, then support knuckle aside to allow clearance for joint removal. 5. Remove grease
fitting, then press ball joint assembly out of lower control arm using a suitable tool, Fig. 9. 6. Press
replacement joint into arm using suitable tools, Fig. 10. Fit spindle over ball stud, install washer, if
equipped, and retaining nut. 7. Tighten retaining nut to specifications. 8. Tighten nut an additional
1/16 turn, if necessary, to align hole in ball stud with nut, then install cotter pin.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Control Arm > Control Arm Bushing >
Component Information > Service and Repair > Differential Carrier Bushings (Upper Control Arm Rear Bushings)
Control Arm Bushing: Service and Repair Differential Carrier Bushings (Upper Control Arm Rear
Bushings)
Fig. 5 Upper Control Arm Rear Bushing (Differential Carrier Bushing) Removal
Fig. 6 Upper Control Arm Rear Bushing (Differential Carrier Bushing) Installation
The upper control arm rear bushing, which is pressed into the differential carrier, can be replaced
using the following procedure:
1. Raise vehicle and support at frame pads, and support nose of axle housing to prevent assembly
from twisting. 2. Lower rear axle to obtain clearance, disconnect upper control arm from axle and
position aside. 3. Install suitable bushing removal tool as shown in Fig. 5. tighten puller screw and
press bushing out of housing. 4. To install replacement bushing, reverse position of removal tool
and pull bushing into position by tightening screw, Fig. 6.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Control Arm > Control Arm Bushing >
Component Information > Service and Repair > Differential Carrier Bushings (Upper Control Arm Rear Bushings) > Page
7718
Control Arm Bushing: Service and Repair Control Arm Bushings
Fig. 7 Control Arm Bushing Removal
Fig. 8 Control Arm Bushing Installation
1. Raise and support vehicle and remove control arm. 2. Press bushings out of control arm using
suitable tools as shown in Fig. 7 3. Reverse procedure to install, ensuring bushing is properly
seated in control arm, Fig. 8. If replacement bushing fits loosely in control arm, or if
mounting areas are damaged or deformed, control arm must be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Cross-Member > Component Information >
Locations
Cross-Member: Locations
Center Of Rear Crossmember
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Cross-Member > Component Information >
Locations > Page 7722
Antilock Brake System Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Front Steering Knuckle > Component Information
> Technical Service Bulletins > Steering Knuckle Nuts - Revised Torque Specification
Front Steering Knuckle: Technical Service Bulletins Steering Knuckle Nuts - Revised Torque
Specification
FILE IN SECTION: 3 - Steering/Suspension
BULLETIN NO.: 53-33-02A
DATE: June, 1995
SUBJECT: Section 3C - Revised Torque Specification for Steering Knuckle Nuts (Upper and
Lower)
MODELS: 1993-95 Buick Roadmaster 1993-95 Cadillac Fleetwood 1993-95 Chevrolet Caprice
1994-95 Chevrolet Impala SS
The torque specification for upper and lower steering knuckle nuts should be as follows:
Tighten
^ Steering knuckle nut (upper) (1) to 83 Nm (61 lb.ft.), additional tightening may be required to
insert cotter pin (3). Do not exceed 60° additional
tightening.
^ Steering knuckle nut (lower) (2) to 112 Nm (63 lb.ft.), additional tightening may be required to
insert cotter pin (3). Do not exceed 60° additional
tightening.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Relays and Modules - Suspension >
Compressor/Pump Relay, Suspension Control > Component Information > Description and Operation
Compressor/Pump Relay: Description and Operation
DESCRIPTION
The compressor relay is controlled by the height sensor and completes the 12-volt circuit to the
compressor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Sensors and Switches - Suspension > Ride
Height Sensor, Suspension Control > Component Information > Locations
Center Of Rear Crossmember
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Sensors and Switches - Suspension > Ride
Height Sensor, Suspension Control > Component Information > Locations > Page 7735
Ride Height Sensor: Description and Operation
DESCRIPTION
The height sensor controls two circuits, compressor relay coil ground circuit and exhaust solenoid
coil ground circuit. To prevent energizing the compressor relay and exhaust solenoid circuits during
normal ride motions, the sensor circuit provides a predetermined delay before the ground circuit is
completed. The sensor electronically limits compressor run time and exhaust solenoid energized
time. This limit function is necessary to prevent continuous compressor operation in case of a
system leak or continuous exhaust solenoid operation. This timer is reset whenever the ignition is
turned Off and On, or height sensor exhaust or compressor signal changes. The height sensor is
mounted to the body frame in the rear of the vehicle. The sensor actuator arm is attached to the
control arm by a short link
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Sensors and Switches - Suspension > Ride
Height Sensor, Suspension Control > Component Information > Locations > Page 7736
Ride Height Sensor: Testing and Inspection
CAUTION: When diagnostic procedures require that vehicle be raised on a hoist, it is important that
the rear axle assembly remains in the normal trim height position at all times. When a frame
contact hoist is used, two additional jack stands should be used to support the rear axle or control
arms in the normal trim height position.
1. Turn ignition Off, then On. This will reset height sensor timer circuits.
2. Raise vehicle on hoist. Ensure rear wheels or axle housing are supported and that vehicle is at
proper trim height.
3. Disconnect link from height sensor arm, then ensure sensor wiring and harness ground are
connected properly.
4. Move sensor arm upward. There should be a delay of 8-15 seconds before compressor turns on
and shocks start to inflate. As soon as shocks start to fill, stop compressor by moving sensor arm
down.
5. Move sensor arm down below position where compressor stopped. There should be a delay of
8-15 seconds before shocks start to deflate and vehicle lowers.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Sensors and Switches - Suspension > Ride
Height Sensor, Suspension Control > Component Information > Locations > Page 7737
Ride Height Sensor: Adjustments
ADJUSTMENTS
The link should be properly attached to the sensor arm and track bar, when making this
adjustment.
1. Loosen lock bolt securing metal arm to height sensor plastic arm. 2. To raise vehicle trim height,
move plastic arm upward and tighten lock bolt. 3. To lower vehicle trim height, loosen lock bolt
securing metal arm to height sensor plastic arm, then move plastic arm down. 4. If adjustment
cannot be made, check for correct sensor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Sensors and Switches - Suspension > Ride
Height Sensor, Suspension Control > Component Information > Locations > Page 7738
Ride Height Sensor: Service and Repair
WARNING: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
1. Disconnect battery ground cable.
2. Raise and support vehicle.
3. Disconnect harness from sensor electrical connector by squeezing oval sides of the connector
lock to release locking tabs.
4. Remove link from height sensor arm, then remove sensor mounting screws or nuts and the
sensor.
5. Remove sensor mounting bracket to underbody attaching screws and remove bracket.
6. Reverse procedure to install, noting the following:
a. When connecting harness to sensor electrical connector, push connector into sensor plug until
sloped shoulder on rear edge of boss is visible
in plug slot. Push oval connector lock onto plug until its two locking tabs snap over shoulder of
sensor plug.
b. Perform height sensor operational check and adjustment procedure as described under Testing
and Inspection. See: Testing and Inspection
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Stabilizer Shaft <--> [Stabilizer Bar, Sway Control]
> Component Information > Service and Repair
Stabilizer Shaft: Service and Repair
1. Support vehicle at rear axle. 2. Remove bolts securing stabilizer bar to lower control arms. 3.
Reverse procedure to install. Use spacer shims, if needed, placed equally on each side of stabilizer
bar. Tighten attaching bolts with vehicle at curb
height.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Air Dryer, Suspension Control > Component Information > Description and Operation
Air Dryer: Description and Operation
DESCRIPTION
The air dryer, attached to the compressor outlet, performs two system functions. The dryer
contains a dry chemical that absorbs moisture from the air before it is delivered to the shocks.
Moisture is removed from the chemical and returned to the air when system is being exhausted.
The air dryer also contains a valving arrangement that maintains a minimum air pressure of 7-14
psi in the shocks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Air Dryer, Suspension Control > Component Information > Description and Operation > Page 7746
Air Dryer: Testing and Inspection
CAUTION; When diagnostic procedures require that vehicle be raised on a hoist, it is important that
the rear axle assembly remains in the normal trim height position at all times. When a frame
contact hoist is used, two additional jack stands should be used to support the rear axle or control
arms in the normal trim height position.
Fig. 21 Compressor/Dryer Trouble Chart
1. Disconnect wiring from compressor motor and exhaust solenoid terminals.
2. Disconnect existing pressure line from dryer and attach pressure gauge tool No. J 22124-A or
equivalent to dryer fitting.
3. Connect an ammeter to 12 volt source and to compressor.
4. Operate compressor and note the following:
a. Current draw should not exceed 14 amps. b. When gauge reads at least 100 psi, turn
compressor Off by disconnecting power supply and observe if pressure leaks down. Compressor
should not leak below 90 psi. If compressor is permitted to run until it reaches maximum output
pressure of 180 psi, the solenoid exhaust valve will act as a relief valve. The resulting leak down
when compressor is shutoff will indicate a false leak.
c. Refer to chart shown in Fig. 21 if compressor fails to meet specification. d. If performance is
satisfactory, install compressor and connect wiring and air lines.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Air Dryer, Suspension Control > Component Information > Description and Operation > Page 7747
Air Dryer: Service and Repair
CAUTION: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
Fig. 23 Air Dryer Assembly
1. Remove compressor as described in Shield, Compressor & Bracket. See:
Compressor/Pump/Service and Repair/Shield, Compressor & Bracket
2. Rotate dryer retainer spring 90° and pull dryer and O-ring out of compressor head assembly, Fig.
23.
3. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Locations
Front Frame Rail
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Locations > Page 7751
Compressor/Pump: Description and Operation
DESCRIPTION
This assembly is a single-piston air pump powered by a 12-volt DC permanent magnet motor. The
compressor head casting contains intake and exhaust valves plus a solenoid-operated exhaust
valve which releases air from the system when energized.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Locations > Page 7752
Compressor/Pump: Testing and Inspection
CAUTION: When diagnostic procedures require that vehicle be raised on a hoist, it is important that
the rear axle assembly remains in the normal trim height position at all times. When a frame
contact hoist is used, two additional jack stands should be used to support the rear axle or control
arms in the normal trim height position.
Fig. 21 Compressor/Dryer Trouble Chart
1. Disconnect wiring from compressor motor and exhaust solenoid terminals.
2. Disconnect existing pressure line from dryer and attach pressure gauge tool No. J 22124-A or
equivalent to dryer fitting.
3. Connect an ammeter to 12 volt source and to compressor.
4. Operate compressor and note the following:
a. Current draw should not exceed 14 amps. b. When gauge reads at least 100 psi, turn
compressor Off by disconnecting power supply and observe if pressure leaks down. Compressor
should not leak below 90 psi. If compressor is permitted to run until it reaches maximum output
pressure of 180 psi, the solenoid exhaust valve will act as a relief valve. The resulting leak down
when compressor is shutoff will indicate a false leak.
c. Refer to chart shown in Fig. 21 if compressor fails to meet specification. d. If performance is
satisfactory, install compressor and connect wiring and air lines.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Service and Repair > Compressor Head Assembly
Compressor/Pump: Service and Repair Compressor Head Assembly
Fig. 24 Compressor Head Assembly
1. Remove air dryer assembly as described in AIR DRYER. See: Air Dryer/Service and Repair
2. Remove three compressor head mounting bolts and head assembly, Fig. 24.
3. Reverse procedure to install, using a new O-ring and torquing head mounting bolts to 36 inch
lbs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Service and Repair > Compressor Head Assembly >
Page 7755
Compressor/Pump: Service and Repair Shield, Compressor & Bracket
CAUTION: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
1. Disconnect battery ground cable.
2. Raise and support vehicle.
3. Remove compressor shield, if equipped, then deflate system.
4. Disconnect high pressure line at air dryer by revolving spring clip 90° while holding connector
end and removing tube assembly.
5. Disconnect electrical connector from compressor pigtail harness.
6. Remove three compressor mounting screws, then the compressor.
7. Remove three compressor mounting bracket screws, then the bracket.
8. If replacing compressor assembly, remove dryer and dryer bracket.
9. Reverse procedure to install. After connecting battery ground cable, cycle ignition switch, then
test system operation, looking for air leaks at dryer.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Service and Repair > Compressor Head Assembly >
Page 7756
Compressor/Pump: Service and Repair Solenoid Valve Assembly
CAUTION: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
If solenoid valve assembly requires replacement, it should be replaced with compressor head
assembly. Refer to COMPRESSOR HEAD ASSEMBLY. See: Compressor Head Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Service and Repair > Compressor Head Assembly >
Page 7757
Compressor/Pump: Service and Repair Air Compressor Service
CAUTION: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
Fig. 25 Air Compressor, Disassembled
Disassembly
1. Remove the seven compressor cover screws, then the compressor cover and gasket, Fig. 25.
2. Remove head and solenoid assembly.
3. Remove two filters, exhaust valve, spring and air dryer O-ring from head assembly.
4. Remove solenoid from head by lifting slightly and sliding to the dryer outlet side.
5. Remove O-ring from solenoid assembly.
6. Remove head gasket from cylinder assembly.
7. Remove four mounting bracket screws, then the bracket and gasket. Note position of ground
wire for installation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump, Suspension Control > Component Information > Service and Repair > Compressor Head Assembly >
Page 7758
Fig. 26 Air Compressor Head Tightening Sequence
Assembly
1. Install gasket and mounting bracket, then the ground wire and screws.
2. Install head gasket on cylinder assembly.
3. Install O-ring on solenoid assembly, then the solenoid in the head with valve opposite air dryer
outlet.
4. Install two filters, exhaust valve and spring on head assembly.
5. Install gasket and cover on head assembly, then four short cover screws.
6. Install head and cover assembly to cylinder assembly using three long screws. Torque all seven
screws in sequence, Fig. 26, to 36 inch lbs.
7. Install air dryer O-ring on compressor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Compressor/Pump Relay, Suspension Control > Component Information > Description and Operation
Compressor/Pump Relay: Description and Operation
DESCRIPTION
The compressor relay is controlled by the height sensor and completes the 12-volt circuit to the
compressor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Level Control Solenoid Valve > Component Information > Description and Operation
Level Control Solenoid Valve: Description and Operation
DESCRIPTION
The exhaust solenoid is located in the compressor head assembly and provides two functions. The
solenoid exhausts air from the system when energized by the height sensor. It also acts as a
pressure relief valve to limit maximum pressure output of the compressor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Ride Height Sensor, Suspension Control > Component Information > Locations
Center Of Rear Crossmember
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7768
Ride Height Sensor: Description and Operation
DESCRIPTION
The height sensor controls two circuits, compressor relay coil ground circuit and exhaust solenoid
coil ground circuit. To prevent energizing the compressor relay and exhaust solenoid circuits during
normal ride motions, the sensor circuit provides a predetermined delay before the ground circuit is
completed. The sensor electronically limits compressor run time and exhaust solenoid energized
time. This limit function is necessary to prevent continuous compressor operation in case of a
system leak or continuous exhaust solenoid operation. This timer is reset whenever the ignition is
turned Off and On, or height sensor exhaust or compressor signal changes. The height sensor is
mounted to the body frame in the rear of the vehicle. The sensor actuator arm is attached to the
control arm by a short link
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7769
Ride Height Sensor: Testing and Inspection
CAUTION: When diagnostic procedures require that vehicle be raised on a hoist, it is important that
the rear axle assembly remains in the normal trim height position at all times. When a frame
contact hoist is used, two additional jack stands should be used to support the rear axle or control
arms in the normal trim height position.
1. Turn ignition Off, then On. This will reset height sensor timer circuits.
2. Raise vehicle on hoist. Ensure rear wheels or axle housing are supported and that vehicle is at
proper trim height.
3. Disconnect link from height sensor arm, then ensure sensor wiring and harness ground are
connected properly.
4. Move sensor arm upward. There should be a delay of 8-15 seconds before compressor turns on
and shocks start to inflate. As soon as shocks start to fill, stop compressor by moving sensor arm
down.
5. Move sensor arm down below position where compressor stopped. There should be a delay of
8-15 seconds before shocks start to deflate and vehicle lowers.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7770
Ride Height Sensor: Adjustments
ADJUSTMENTS
The link should be properly attached to the sensor arm and track bar, when making this
adjustment.
1. Loosen lock bolt securing metal arm to height sensor plastic arm. 2. To raise vehicle trim height,
move plastic arm upward and tighten lock bolt. 3. To lower vehicle trim height, loosen lock bolt
securing metal arm to height sensor plastic arm, then move plastic arm down. 4. If adjustment
cannot be made, check for correct sensor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Control ( Automatic - Electronic ) >
Ride Height Sensor, Suspension Control > Component Information > Locations > Page 7771
Ride Height Sensor: Service and Repair
WARNING: When repair or adjustment procedures require that vehicle be raised on a hoist, it is
important that the rear axle assembly remains in the normal trim height position at all times. When
a frame contact hoist is used, two additional jack stands should be used to support the rear axle or
control arms in the normal trim height position.
1. Disconnect battery ground cable.
2. Raise and support vehicle.
3. Disconnect harness from sensor electrical connector by squeezing oval sides of the connector
lock to release locking tabs.
4. Remove link from height sensor arm, then remove sensor mounting screws or nuts and the
sensor.
5. Remove sensor mounting bracket to underbody attaching screws and remove bracket.
6. Reverse procedure to install, noting the following:
a. When connecting harness to sensor electrical connector, push connector into sensor plug until
sloped shoulder on rear edge of boss is visible
in plug slot. Push oval connector lock onto plug until its two locking tabs snap over shoulder of
sensor plug.
b. Perform height sensor operational check and adjustment procedure as described under Testing
and Inspection. See: Testing and Inspection
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Spring ( Coil / Leaf ) > Component
Information > Service and Repair > Front Coil Spring
Suspension Spring ( Coil / Leaf ): Service and Repair Front Coil Spring
Fig. 11 Coil Spring Position
1. Raise and support front of vehicle, then remove wheel and tire assembly. Support vehicle by
frame so control arms hang free. 2. On models equipped with anti-lock brake systems, remove
right and left wheel speed sensors as follows:
a. Under vehicle hood, disconnect speed sensor electrical harness. b. Raise and support vehicle,
then remove speed sensor harness bracket attaching bolt. c. Remove speed sensor to steering
knuckle attaching bolt, then remove speed sensor and bracket assembly and position aside. d.
Reverse procedure to install. Wheel speed sensors are to installed by hand. Do not hammer
sensors into position, as damage may result.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Spring ( Coil / Leaf ) > Component
Information > Service and Repair > Front Coil Spring > Page 7776
3. On all models, remove stabilizer to lower control arm attachment. 4. Disconnect tie rod end from
steering knuckle. 5. Install a suitable coil spring compressor, then compress coil spring. 6. Remove
lower control arm to frame bolts, then pivot lower control arm rearward. 7. Carefully loosen coil
spring compressor and remove coil spring from vehicle. 8. Reverse procedure to install. Position
coil spring as shown in Fig. 11. Install front pivot bolt first. To ensure adequate suspension
clearance,
install front pivot bolt from front, with nut toward rear of vehicle. Rear bolt can be installed from
either direction.
9. Tighten pivot bolts to specifications.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Spring ( Coil / Leaf ) > Component
Information > Service and Repair > Front Coil Spring > Page 7777
Suspension Spring ( Coil / Leaf ): Service and Repair Rear Coil Spring
Fig. 3 Coil Spring Installation
If more than one coil spring is being replaced, remove and install one spring at a time to prevent
axle assembly from slipping or twisting out of position.
1. Support vehicle at frame and rear axle. 2. On models equipped with anti-lock brake systems,
remove rear axle speed sensor as follows:
a. Disconnect speed sensor electrical harness. b. Remove speed sensor harness bracket attaching
bolt. c. Remove speed sensor to rear axle attaching bolt, then remove speed sensor and bracket
assembly and position aside.
3. On all models, disconnect shock absorbers at lower mountings. 4. Disconnect upper control
arms from axle housing. 5. Disconnect stabilizer bar from either right or lefthand side of control
arm, if equipped. 6. On models equipped with electronic suspension, disconnect height sensor arm
link. 7. On all models, remove brake hose support bolt and support without disconnecting brake
lines. 8. Lower axle until spring can be removed, then remove spring and insulator. 9. Reverse
procedure to install, noting the following:
a. Springs must be installed with an insulator between upper seat and spring and positioned
properly, Fig. 3 b. Install anti-lock brake wheel speed sensors by hand. Do not hammer sensors
into position, as damage may result.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Technical Service Bulletins > Suspension - Shock Absorber/Strut Leakage Information
Suspension Strut / Shock Absorber: Technical Service Bulletins Suspension - Shock
Absorber/Strut Leakage Information
INFORMATION
Bulletin No.: 05-03-08-002C
Date: October 16, 2009
Subject: Information on Replacement of Shock Absorbers and Struts Due to Fluid Leaks
Models:
2010 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2010 model year and Inspection Procedures.
Please discard Corporate Bulletin Number 05-03-08-002B (Section 03 - Suspension).
This bulletin is intended to help identify the severity of shock absorber and strut fluid seepage.
Improper diagnosis may lead to components being replaced that are within the manufacturer's
specification. Shock absorbers and strut assemblies are fluid-filled components and will normally
exhibit some seepage. Seepage is defined as oil film or dust accumulation on the exterior of the
shock housing. Shock absorbers and struts are not to be replaced under warranty for seepage.
Use the following information to determine if the condition is normal acceptable seepage or a
defective component.
Important Electronically controlled shock absorbers (MR) may have a tendency to attract dust to
this oil film. Often this film and dust can be wiped off and will not return until similar mileage is
accumulated again.
Inspection Procedure
Note
The shock absorber or strut assembly DOES NOT have to be removed from the vehicle to perform
the following inspection procedure.
Use the following descriptions and graphics to determine the serviceability of the component.
Shock Absorbers
Do Not Replace shock absorbers displaying condition 1 or 2 levels of seepage.
1. Oil or fluid residue only on the bottom or top of the shock absorber and not originating from the
shaft seal (the upper part of the lower shock tube). 2. Light film/residue on approximately 1/3 (a) or
less of the lower shock tube (A) and originating from the shaft seal.
Replace shock absorbers displaying conditions 3 and 4 levels of leaks.
3. Oil drip or trail down the lower shock tube and originating from the shaft seal. 4. An extreme wet
film of oil covering more than 1/3 (b) of the lower shock tube and originating from the shaft seal.
Coil-over Shock Absorber
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Technical Service Bulletins > Suspension - Shock Absorber/Strut Leakage Information > Page 7782
Do Not Replace coil-over shock absorbers displaying condition 1 or 2 levels of seepage.
1. Oil or fluid residue only on the bottom of the lower shock absorber tube or the coil-over shock
absorber components and not originating from the
shaft seal (located at the top of the coil-over shock tube).
2. Light film/residue on the shock absorber tube, but not on the spring seat and originating from the
shaft seal.
Replace coil-over shock absorbers displaying conditions 3 and 4 levels of leaks.
3. Oil drip or trail down the lower shock tube and originating from the shaft seal. 4. An extreme, wet
film of oil covering the shock absorber tube and pooling in the spring seat and originating from the
shaft seal.
Struts
Do Not Replace Struts displaying condition 1 or 2 levels of seepage.
1. Oil or fluid residue only on the bottom of the strut tube or on other strut components and not
originating from the shaft seal. 2. Light film/residue on the strut tube, but not on the spring seat and
originating from the shaft seal.
Replace Struts displaying conditions 3 and 4 levels of leaks.
3. Oil drip or trail down the strut tube and originating from the shaft seal (located at the top of the
strut tube). 4. Extreme wet film of oil covering the strut tube and pooling in the spring seat and
originating from the shaft seal.
Correction
Use the information published in SI for diagnosis and repair.
Use the applicable published labor operation.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Technical Service Bulletins > Suspension - Shock Absorber/Strut Leakage Information > Page 7783
Suspension Strut / Shock Absorber: Technical Service Bulletins Suspension - Shock
Absorber/Strut Replacement Guidlines
File In Section: Warranty Administration
Bulletin No.: 72-05-12
Date: January, 1998
WARRANTY ADMINISTRATION
Subject: Replacement of Shock Absorbers and Struts Labor Operations E3800, E3801, E3807,
E5800, E5801, E5807, E3850, E3851, E3857, E5750, E5751, and E5757
Models: All Past, Present, and Future Passenger Cars & Trucks
The purpose of this bulletin is to provide retail and wholesale service personnel with enhanced
service policies for the above listed subject labor operations.
Service Management should make certain that all dealership personnel responsible for
replacement of suspension components are familiar with GM Service Manual procedures.
Effective with repair orders dated on or after January 15, 1998 the following must also be followed:
- Shock absorber/strut assemblies are fluid filled components and will normally exhibit seepage.
Seepage is defined as oil film or dust accumulation on the exterior of the shock housing. Shock
absorber/strut assemblies are not to be replaced under warranty or seepage.
- Defective shock absorber/strut assemblies will have a visible oil path or drip coming from the
component. A visible oil path or drip coming from the shock absorber/strut assembly should be
replaced as a defective component.
- Only defective shock absorber/strut assemblies should be replaced. DO NOT replace pairs unless
both are defective, unless otherwise instructed in the Service Manual and/or Service Bulletin.
- Service Management approval is required on the repair order for replacement of struts or shocks
in pairs. This approval includes noting the reason for replacement.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Technical Service Bulletins > Page 7784
Suspension Strut / Shock Absorber: Description and Operation
DESCRIPTION
The shocks are constructed with a plastic sleeve attached to the dust tube and reservoir. This
sleeve forms a flexible chamber which will extend the shock when air pressure is increased. In
order to maintain proper operation and reliability, a minimum pressure of 7-14 psi must be
maintained in the system at all times.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber
Suspension Strut / Shock Absorber: Service and Repair Front Suspension Shock Absorber
Front Shock Absorber Attachments
Removing Shock Absorber Upper Nut
SPECIAL TOOL REQUIRED (or equivalent)
^ J-25591, Shock absorber nut wrench.
REMOVE OR DISCONNECT
1. Raise and suitably support vehicle. 2. Hold the shock absorber upper stem using J-25591 to
keep it from turning. 3. Nut, retainer and insulator. 4. Lower shock bolts/screws and pull the shock
absorber out from the bottom. 5. Inspect lower control arm nuts and replace if necessary.
INSTALL OR CONNECT
1. With the retainer and insulator in place over the upper stem, install the shock absorber (fully
extended) up through the lower control arm and
spring so that the upper stem passes through the mounting hole in the frame.
2. Insulator, retainer and nut over the shock absorber upper stem.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber > Page 7787
3. Using J-25591, hold the upper stem to keep it from turning and tighten the nut to 11 Nm (97 lb
in). 4. Lower shock bolts/screws attaching the shock absorber lower pivot to the control arm and
tighten to 27 Nm (20 ft lbs). 5. Lower vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber > Page 7788
Suspension Strut / Shock Absorber: Service and Repair Rear Suspension
(Figure 1) Rear Shock Absorber
REMOVE OR DISCONNECT
1. Raise and suitably support vehicle. 2. Support rear axle. 3. Air line from air adjustable shock
absorber, if equipped, by turning spring clip 90° and pulling gently on air line housing. 4. Nuts and
bolts/screws from shock absorber at frame.
CAUTION: When removing the lower attaching nut, the stud must not turn. A hex is located on the
stud between the bracket and the shock absorber so that a wrench can be used to keep the stud
from turning. Failure to hold the stud may cause damage to the mechanical bond between the
shock absorber and the stud.
5. Nut and washer from shock absorber. 6. Shock absorber. 7. Shield from shock absorber, if
equipped.
INSTALL OR CONNECT
1. Shield to shock absorber, if equipped. Position so that "V" notch near clamp is 180° from air tube
fitting and rim of shield is seat against rubber
rim of shock absorber boot.
2. Shock absorber. 3. Bolts/screws and nuts loosely at frame.
CAUTION: When tightening lower attaching nut, the stud must not turn. A hex is located on the
stud between the bracket and the shock absorber so a wrench can be used to keep the stud from
turning. Failure to hold the stud may cause damage to the mechanical bond between the shock
absorber and the stud.
4. Washer and nut at rear axle housing and tighten nut to 85 Nm (63 lb ft). 5. Air line to air
adjustable shock absorber, if equipped. 6. Remove support from rear axle. 7. Lower vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber > Page 7789
Suspension Strut / Shock Absorber: Service and Repair Strut Air Bladder
Fig. 82 Upper Strut Mount Removal.
Fig. 83 Outer Clamp Removal.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber > Page 7790
Fig. 84 O-ring Replacement.
Fig. 85 Inner Clamp Removal.
REMOVAL
1. Remove strut from vehicle. 2. Scribe alignment marks between upper mount and outer tube. 3.
Clamp strut in a suitable vise using wooden blocks. 4. Remove upper mount from strut, Fig. 82. 6.
Cut and remove outer clamp with a hacksaw, Fig. 83. 6. Cut air bladder from outer tube and slide
the inner tube upward. 7. Remove O-ring from inside top of outer tube, Fig. 84. 8. Cut and remove
inner clamp with a hacksaw, Fig. 85. 9. Remove air bladder from inner tube.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber > Page 7791
Fig. 86 Air Bladder Replacement.
Fig. 87 Inner Clamp & Air Bladder Positioning.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Suspension Strut / Shock Absorber > Component
Information > Service and Repair > Front Suspension Shock Absorber > Page 7792
Fig. 88 Air Fitting Positioning.
INSTALLATION
1. Lubricate new O-ring and O-ring groove with silicone lubricant. Install O-ring in groove, Fig. 84.
2. Apply silicone lubricant to inside top of entire outside of new air bladder, Fig. 86. 3. Fold bottom
of air bladder before installation on inner tube. Place air bladder over inner tube, continuing to fold
bladder from the bottom up.
Position top of air bladder as shown in Fig. 87.
CAUTION: Do not use tools to fold air bladder as damage may occur, causing air leakage.
4. Place inner clamp in position as shown in Fig. 87. Tighten clamp with sealing ring compressor
tool No. J-34649, or equivalent. 5. Fold bottom of air bladder upward and fold top of 4 inch section
downward. 6. Apply silicone lubricant to polished diameter of inner shaft tube. 7. Place outer tube
over air bladder and push downward against folded portion of bladder. Outer tube must be
completely seated over shaft. 8. Install upper mount onto strut, aligning marks made during
disassembly, and torque nut to 74 ft. lbs. Upper mount and tube air fitting must be
properly positioned with the bottom strut mount, Fig. 88.
9. Apply silicone lubricant to outer tube.
10. Install air bladder over outer tube by folding upward over tube and push over tube. 11. Install
and tighten hose clamp over grooved area of air bladder. 12. Support strut and partially inflate air
bladder. Check for leaks with soap solution. 13. Install strut into vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Wheel Bearing > Component Information >
Adjustments
Wheel Bearing: Adjustments
FRONT WHEEL BEARINGS ADJUSTMENT
Fig. 2 Front Wheel Bearing Adjustment
1. While rotating wheel forward, torque spindle nut to 12 ft. lbs., Fig. 2. 2. Back off nut until just
loose then hand tighten nut and back it off again until either hole in spindle lines up with hole in nut.
Do not back off nut
more than 1/2 flat.
3. Install new cotter pin. With wheel bearing properly adjusted, there will be .001-.005 inch end
play.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Suspension > Wheel Bearing > Component Information >
Adjustments > Page 7796
Wheel Bearing: Service and Repair
FRONT WHEEL BEARINGS
Fig. 3 Hub & Wheel Bearing Replacement
1. Raise car and remove front wheels. 2. On models equipped with anti-lock brake systems,
remove right and left wheel speed sensors as follows:
a. Under vehicle hood, disconnect speed sensor electrical harness. b. Raise and support vehicle,
then remove speed sensor harness bracket attaching bolt. c. Remove speed sensor to steering
knuckle attaching bolt, then remove speed sensor and bracket assembly and position aside. d.
Reverse procedure to install. Install wheel speed sensors by hand. Do not hammer sensors into
position, as damage may result.
3. On all models, remove bolts holding brake caliper to its mounting and insert a fabricated block
(11/16 x 1 1/16 x 2 inches in length) between
brake pads as caliper is being removed. Once removed, caliper can be wired or secured in some
manner away from disc.
4. Remove spindle nut and hub and disc assembly. Grease retainer and inner wheel bearing can
now be removed, Fig. 3. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Vehicle Lifting > Component Information >
Service and Repair
Vehicle Lifting: Service and Repair
Vehicle Lift Points
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires
Tires: Technical Service Bulletins Wheels/Tires - Use of Nitrogen Gas in Tires
INFORMATION
Bulletin No.: 05-03-10-020C
Date: April 27, 2010
Subject: Use of Nitrogen Gas in Tires
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 05-03-10-020B (Section 03 - Suspension).
GM's Position on the Use of Nitrogen Gas in Tires
General Motors does not oppose the use of purified nitrogen as an inflation gas for tires. We expect
the theoretical benefits to be reduced in practical use due to the lack of an existing infrastructure to
continuously facilitate inflating tires with nearly pure nitrogen. Even occasional inflation with
compressed atmospheric air will negate many of the theoretical benefits. Given those theoretical
benefits, practical limitations, and the robust design of GM original equipment TPC tires, the
realized benefits to our customer of inflating their tires with purified nitrogen are expected to be
minimal.
The Promise of Nitrogen: Under Controlled Conditions
Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer
through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile
racing. The following benefits under controlled conditions are attributed to nitrogen gas and its
unique properties:
- A reduction in the expected loss of Tire Pressure over time.
- A reduction in the variance of Tire Pressures with temperature changes due to reduction of water
vapor concentration.
- A reduction of long term rubber degradation due to a decrease in oxygen concentrations.
Important These are obtainable performance improvements when relatively pure nitrogen gas is
used to inflate tires under controlled conditions.
The Promise of Nitrogen: Real World Use
Nitrogen inflation can provide some benefit by reducing gas migration (pressure loss) at the
molecular level through the tire structure. NHTSA (National Highway Traffic Safety Administration)
has stated that the inflation pressure loss of tires can be up to 5% a month. Nitrogen molecules are
larger than oxygen molecules and, therefore, are less prone to "seeping" through the tire casing.
The actual obtainable benefits of nitrogen vary, based on the physical construction and the
materials used in the manufacturing of the tire being inflated.
Another potential benefit of nitrogen is the reduced oxidation of tire components. Research has
demonstrated that oxygen consumed in the oxidation process of the tire primarily comes from the
inflation media. Therefore, it is reasonable to assume that oxidation of tire components can be
reduced if the tire is inflated with pure nitrogen. However, only very small amounts of oxygen are
required to begin the normal oxidation process. Even slight contamination of the tire inflation gas
with compressed atmospheric air during normal inflation pressure maintenance, may negate the
benefits of using nitrogen.
GM Tire Quality, Technology and Focus of Importance
Since 1972, General Motors has designed tires under the TPC (Tire Performance Criteria)
specification system, which includes specific requirements that ensure robust tire performance
under normal usage. General Motors works with tire suppliers to design and manufacture original
equipment tires for GM vehicles. The GM TPC addresses required performance with respect to
both inflation pressure retention, and endurance properties for original equipment tires. The
inflation pressure retention requirements address availability of oxygen and oxidation concerns,
while endurance requirements ensure the mechanical structure of the tire has sufficient strength.
This combination has provided our customers with tires that maintain their structural integrity
throughout their useful treadlife under normal operating conditions.
Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure
maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Maintaining the
correct inflation pressure allows the tire to perform as intended by the vehicle manufacturer in
many areas, including comfort, fuel economy, stopping distance, cornering, traction, treadwear,
and noise. Since the load carrying capability of a tire is related to inflation pressure, proper inflation
pressure maintenance is necessary for the tire to support the load imposed by the vehicle without
excessive structural
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7805
degradation.
Important Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure
maintenance of tires is critical for overall tire, and ultimately, vehicle performance.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7806
Tires: Technical Service Bulletins Tires/Wheels - Tire Puncture Repair Procedures
INFORMATION
Bulletin No.: 04-03-10-001F
Date: April 27, 2010
Subject: Tire Puncture Repair Procedures For All Cars and Light Duty Trucks
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2010 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 04-03-10-001E (Section 03 - Suspension).
This bulletin covers puncture repair procedures for passenger car and light duty truck radial tires in
the tread area only. The tire manufacturer must be contacted for its individual repair policy and
whether or not the speed rating is retained after repair.
Caution
- Tire changing can be dangerous and should be done by trained professionals using proper tools
and procedures. Always read and understand any manufacturer's warnings contained in their
customers literature or molded into the tire sidewall.
- Serious eye and ear injury may result from not wearing adequate eye and ear protection while
repairing tires.
- NEVER inflate beyond 275 kPa (40 pounds) pressure to seat beads.
Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may
require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be
used. Consult the tire manufacturer for its individual repair policy.
- NEVER stand, lean or reach over the assembly during inflation.
Repairable area on a radial tire.
Important
- NEVER repair tires worn to the tread indicators 1.59 mm (2/32") remaining depth).
- NEVER repair tires with a tread puncture larger than 6.35 mm (1/4").
- NEVER substitute an inner tube for a permissible or non-permissible repair.
- NEVER perform an outside-in tire repair (plug only, on the wheel).
- Every tire must be removed from the wheel for proper inspection and repair.
- Regardless of the type of repair used, the repair must seal the inner liner and fill the injury.
- Consult with repair material supplier/manufacturer for repair unit application procedures and
repair tools/repair material recommendations.
Three basic steps for tire puncture repair:
1. Remove the tire from the wheel for inspection and repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7807
2. Fill the injury (puncture) to keep moisture out. 3. Seal the inner liner with a repair unit to prevent
air loss.
External Inspection
1. Prior to demounting, inspect the tire surface, the valve and the wheel for the source of the leak
by using a water and soap solution. Mark the
injured area and totally deflate the tire by removing the valve core.
2. Demount the tire from the wheel and place the tire on a well-lighted spreader.
Internal Inspection
1. Spread the beads and mark the puncture with a tire crayon. 2. Inspect the inner tire for any signs
of internal damage. 3. Remove the puncturing object, noting the direction of the penetration. 4.
Probe the injury with a blunt awl in order to determine the extent and direction of the injury. 5.
Remove any loose foreign material from the injury. 6. Punctures exceeding 6.35 mm (1/4") should
not be repaired.
Cleaning
1. Clean the area around the puncture thoroughly with a proper liner cleaner, clean cloth and a
scraper. This step serves to remove dirt and mold
lubricants to insure proper adhesion and non-contamination of the buffing tool.
2. Refer to information on the product or manufacturer's Material Safety Data Sheet and follow
guidelines for handling and disposal.
Clean the Injury Channel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7808
1. Use a proper hand reamer, carbide cutter or drill bit to ream the puncture channel from the inside
of the tire in order to clean the injury. 2. Remove steel wires protruding above the liner surface to
prevent damage to the repair unit. 3. Consult your repair material supplier for recommended
reaming tool(s).
Fill the Injury
1. It is necessary to fill the injury channel to provide back up for the repair unit and to prevent
moisture from entering the tire fabric and steel wires. 2. (For combination repair/plug units skip this
step.) Cement the injured channel and fill the injury from the inside of the tire with the repair plug
per
repair material manufacturer's recommendations. Without stretching the plug, cut the plug off just
above the inside tire surface.
3. Consult your repair material supplier for proper repair material selection.
Repair Unit Selection
Important Do not install the repair unit in this step.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7809
1. Center the repair unit over the injury as a reference and outline an area larger than the unit so
that buffing will not remove the crayon marks. 2. Remove the repair unit. 3. DO NOT overlap
previous or multiple repair units. 4. Consult your repair material supplier for proper repair unit
selection.
Buffing
1. To prevent contamination and preserve the outline, buff within the marked area thoroughly and
evenly with a low speed buffing tool using a fine
wire brush or gritted rasp.
2. Buff to a smooth velvet surface (RMA #1 or #2 buffed texture). 3. Use caution not to gouge the
inner liner or expose casing fabric. 4. Remove any buffing dust with a vacuum cleaner. 5. Consult
your repair material supplier for a proper buffing tool.
Cementing
Apply chemical cement according to the repair material manufacturer's procedures.
Repair Unit Application
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7810
1. The tire must be in the relaxed position when the repair unit is installed (Do not spread the beads
excessively).
Two-Piece Plug and Repair Units
1. If applicable, install the repair unit so that the alignment is correct. 2. Center the repair unit over
the injury and stitch down thoroughly with the stitching tool, working from the center out.
3. Being careful not to stretch the plug material, cut the plug flush with the outer tread.
Combination Repair/Plug Units
1. Pull the plug through the injury until the repair just reaches the liner. Stitch down thoroughly. 2.
Follow the repair material manufacturer's recommendations for further installation instructions.
2. Consult your repair material supplier for the proper stitching tool.
Safety Cage
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7811
Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may
require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be
used. Consult the tire manufacturer for its individual repair policy.
Final Inspection
1. After remounting and inflating the tire, check both beads, the repair and the valve with a water
and soap solution in order to detect leaks. 2. If the tire continues to lose air, the tire must be
demounted and reinspected. 3. Balance the tire and wheel assembly. Refer to Tire and Wheel
Assembly Balancing - OFF Vehicle.
For additional tire puncture repair information, contact:
Rubber Manufacturers Association (RMA)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7812
Tires: Technical Service Bulletins Tires - Correct Inflation Pressure Information
INFORMATION
Bulletin No.: 00-00-90-002J
Date: January 28, 2009
Subject: Information on Proper Tire Pressure
Models: 2010 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2009 and
Prior HUMMER H2, H3, H3T 2005-2009 Saab 9-7X
Supercede:
This bulletin is being revised to add model years and clarify additional information. Please discard
Corporate Bulletin Number 00-00-90-002I (Section 00 - General Information).
Important:
^ Adjustment of tire pressure for a customer with a Low Tire Pressure Monitor (TPM) light on and
no codes in the TPM system is NOT a warrantable repair. Claims to simply adjust the tire pressure
will be rejected.
^ ALL tires (including the spare tire) MUST be set to the recommended inflation pressure stated on
the vehicle's tire placard (on driver's door) during the PRE-DELIVERY INSPECTION (PDI).
Recommended inflation pressure is not the pressure printed on tire sidewall.
^ Tires may be over-inflated from the assembly plant due to the mounting process.
^ Generally a 5.6°C (10°F) temperature change will result in (is equivalent to) a 6.9 kPa (1 psi) tire
pressure change.
^ 2008-2009 HUMMER H2 Only - The H2 comes standard with Light Truck "D" Load Range tires
with a recommended cold inflation pressure of 289 kPa (42 psi). These tires will alert the driver to a
low pressure situation at roughly 262 kPa (38 psi) due to a requirement in FMVSS 138 which
specifies a Minimum Activation Pressure for each tire type. This creates a relatively narrow window
of "usable" pressure values and the warning will be more sensitive to outside temperature changes
during the colder months. As with other cold temperature/tire pressure issues, there is nothing
wrong with the system itself. If a vehicle is brought in with this concern, check for tire damage and
set all tires to the Recommended Cold Inflation Pressure shown on the vehicle placard.
Accurate tire pressures ensure the safe handling and appropriate ride characteristics of GM cars
and trucks. It is critical that the tire pressure be adjusted to the specifications on the vehicle¡C■s
tire placard during PDI.
Ride, handling and road noise concerns may be caused by improperly adjusted tire pressure.
The first step in the diagnosis of these concerns is to verify that the tires are inflated to the correct
pressures. The recommended tire inflation pressure is listed on the vehicle¡C■s tire placard. The
tire placard is located on the driver¡C■s side front or rear door edge, center pillar, or the rear
compartment lid.
Tip
^ Generally a 5.6°C (10°F) temperature increase will result in (is equivalent to) a 6.9 kPa (1 psi) tire
pressure increase.
^ The definition of a "cold" tire is one that has been sitting for at least 3 hours, or driven no more
than 1.6 km (1 mi).
^ On extremely cold days, if the vehicle has been indoors, it may be necessary to compensate for
the low external temperature by adding additional air to the tire during PDI.
^ During cold weather, the Tire Pressure Monitor (TPM) indicator light (a yellow horseshoe with an
exclamation point) may illuminate. If this indicator turns off after the tires warm up (reach operating
temperature), the tire pressure should be reset to placard pressure at the cold temperature.
^ The TPM system will work correctly with nitrogen in tires.
^ The TPM system is compatible with the GM Vehicle Care Tire Sealant but may not be with other
commercially available sealants.
Important:
^ Do not use the tire pressure indicated on the tire itself as a guide.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Wheels/Tires - Use of Nitrogen Gas in Tires > Page 7813
^ Always inspect and adjust the pressure when the tires are cold.
^ Vehicles that have different pressures for the front and the rear need to be adjusted after tire
rotation.
Improper tire inflation may result in any or all of the following conditions:
^ Premature tire wear
^ Harsh ride
^ Excessive road noise
^ Poor handling
^ Reduced fuel economy
^ Low Tire Pressure Monitor (TPM) Light ON
^ Low Tire Pressure Message on the Drivers Information Center (DIC)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Tires > Component Information > Technical
Service Bulletins > Page 7814
Tires: Specifications
Front ....................................................................................................................................................
......................................................... 210 kPa (30 psi) Rear ................................................................
.............................................................................................................................................. 210 kPa
(30 psi) Full-Size Spare .......................................................................................................................
...................................................................... 240 kPa (35 psi)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation
(RFV)
Wheels: Customer Interest Wheels/Tires - Tire Radial Force Variation (RFV)
INFORMATION
Bulletin No.: 00-03-10-006F
Date: May 04, 2010
Subject: Information on Tire Radial Force Variation (RFV)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3 2009
and Prior Saab 9-7X 2000-2005 Saturn L Series 2003-2007 Saturn ION
Supercede: This bulletin is being revised to considerably expand the available information on
Radial Force Variation (RFV) and should be reviewed in whole. Please discard Corporate Bulletin
Number 00-03-10-006E (Section 03 - Suspension).
Important
- Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven
a minimum of 16 km (10 mi) to ensure removal of any flat-spotting. Refer to Corporate Bulletin
Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original Equipment Tires.
- Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel
assemblies for each vehicle.
The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation
measurement equipment, such as the Hunter GSP9700. This type of equipment can be a valuable
tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force
variation is highway speed shake on smooth roads.
Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out
of round and tire force variation. These three conditions are not necessarily related. All three
conditions must be addressed.
Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle,
two plane dynamic wheel balancers are readily available and can accurately correct any
imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer,
and proper balance weights, are all factors required for a quality balance. However, a perfectly
balanced tire/wheel assembly can still be "oval shaped" and cause a vibration.
Before balancing, perform the following procedures.
Tire and Wheel Diagnosis
1. Set the tire pressure to the placard values. 2. With the vehicle raised, ensure the wheels are
centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while
shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick.
3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and
correct as necessary:
- Missing balance weights
- Bent rim flange
- Irregular tire wear
- Incomplete bead seating
- Tire irregularities (including pressure settings)
- Mud/ice build-up in wheel
- Stones in the tire tread
- Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to
diagnosing a smooth road shake condition.
4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a
sufficient distance on a known, smooth road
surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes
are applied lightly and the pulsation felt in the steering wheel increases, refer to the Brakes section
of the service manual that deals with brake-induced pulsation. If you can start to hear the vibration
as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order
(one pulse per propshaft revolution) driveline vibration. Driveline first order vibrations are high
enough in frequency that most humans can start to hear them at highway speeds, but are too high
to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment.
If the vehicle exhibits this low boom and the booming pulses in-and-out on a regular basis (like a
throbbing), chances are good that the vehicle could have driveline vibration. This type
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation
(RFV) > Page 7823
of vibration is normally felt more in the "seat of the pants" than the steering wheel.
5. Next, record the Hertz (Hz) reading as displayed by the EVA onto the tire data worksheet found
at the end of this bulletin. This should be done
after a tire break-in period of at least 16 km (10 mi) at 72 km/h (45 mph) or greater, in order to
eliminate any possible tire flat-spotting. This reading confirms what the vehicle vibration frequency
is prior to vehicle service and documents the amount of improvement occurring as the result of the
various steps taken to repair. Completing the Steering Wheel Shake Worksheet below is required.
A copy of the completed worksheet must be saved with the R.O. and a copy included with any
parts returned to the Warranty Parts Center for analysis. A reading of 35 to 50 Hz typically
indicates a first order propshaft vibration. If this is the situation, refer to Corporate Bulletin Number
08-07-30-044D. Generally, a reading between 10 and 20 Hz indicates a tire/wheel vibration and if
this is the reading obtained, continue using this bulletin. If the tire 1st order vibration goes away
and stays away during this evaluation, the cause is likely tire flat-spotting. Tire flat-spotting vibration
may come and go at any speed over 72 km/h (45 mph) during the first 10 minutes of operation, if
vibration continues after 10 minutes of driving at speeds greater than 72 km/h (45 mph), tire
flat-spotting can be ruled out as the cause for vibration.
6. If flat-spotting is the cause, provide the explanation that this has occurred due to the vehicle
being parked for long periods of time and that the
nature of the tire is to take a set. Refer to Corporate Bulletin Number 03-03-10-007E: Information
on Tire/Wheel Characteristics (Vibration, Balance, Shake, Flat Spotting) of GM Original Equipment
Tires.
7. If the road test indicates a shake/vibration exists, check the imbalance of each tire/wheel
assembly on a known, calibrated, off-car dynamic
balancer.Make sure the mounting surface of the wheel and the surface of the balancer are
absolutely clean and free of debris. Be sure to chose the proper cone/collet for the wheel, and
always use the pilot bore for centering. Never center the wheel using the hub-cap bore since it is
not a precision machined surface. If any assembly calls for more than 1/4 ounce on either rim
flange, remove all balance weights and rebalance to as close to zero as possible. If you can see
the vibration (along with feeling it) in the steering wheel (driving straight without your hands on the
wheel), it is very likely to be a tire/wheel first order (one pulse per revolution) disturbance. First
order disturbances can be caused by imbalance as well as non-uniformities in tires, wheels or
hubs. This first order frequency is too low for a human to hear, but if the amplitude is high enough,
it can be seen.
If a vibration or shake still exists after balancing, any out of round conditions, of the wheel, and
force variation conditions of the tire, must be addressed. Equipment such as the Hunter GSP9700
can address both (it is also a wheel balancer).
Tire radial force vibration (RFV) can be defined as the amount of stiffness variation the tire will
produce in one revolution under a constant load. Radial force variation is what the vehicle feels
because the load (weight) of the vehicle is always on the tires. Although free runout of tires (not
under load) is not always a good indicator of a smooth ride, it is critical that total tire/wheel
assembly runout be within specification.
Equipment such as the Hunter GSP9700 loads the tire, similar to on the vehicle, and measures
radial force variation of the tire/wheel assembly. Note that the wheel is affecting the tire's RFV
measurement at this point. To isolate the wheel, its runout must be measured. This can be easily
done on the Hunter, without the need to set up dial indicators. If the wheel meets the runout
specification, the tire's RFV can then be addressed.
After measuring the tire/wheel assembly under load, and the wheel alone, the machine then
calculates (predicts) the radial force variation of the tire. However, because this is a prediction that
can include mounting inaccuracies, and the load wheel is much smaller in diameter than used in
tire production, this type of service equipment should NOT be used to audit new tires. Rather, it
should be used as a service diagnostic tool to minimize radial force variation of the tire/wheel
assembly.
Equipment such as the Hunter GSP9700 does an excellent job of measuring wheel runout, and of
finding the low point of the wheel (for runout) and the high point of the tire (for radial force
variation). This allows the tire to be matched mounted to the wheel for lowest tire/wheel assembly
force variation.
The machine will simplify this process into easy steps. The following assembly radial force variation
numbers should be used as a guide:
When measuring RFV and match mounting tires perform the following steps.
Measuring Wheel Runout and Assembly Radial Force Variation
Important The completed worksheet at the end of this bulletin must be attached to the hard copy of
the repair order.
- Measure radial force variation and radial runout.
- If a road force/balancing machine is used, record the radial force variation (RFV) on the
worksheet at the end of this bulletin. It may be of benefit to have the lowest RFV assembly to the
front left corner. If the machine is not available and the EVA data suggests there is an issue, swap
the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem
still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those
tires onto the subject vehicle.
- If a runout/balancing machine is used, record the radial runout of the tire/wheel assemblies on the
worksheet at the end of this bulletin. If one or more of the tire/wheel assemblies are more than.040
in (1.02 mm), match mount the tire to the wheel to get below.040 in (1.02 mm). For sensitive
customers, readings of 0.030 inch (0.76 mm) or less are preferable, it may also be of benefit to
have the lowest runout assembly to the front left corner. If the machine is not available and the
EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the
back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do
not exhibit the same frequency and swap those tires
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation
(RFV) > Page 7824
onto the subject vehicle.
- After match mounting, the tire/wheel assembly must be rebalanced.
If match mounting tires to in-spec wheels produces assembly values higher than these, tire
replacement may be necessary. Replacing tires at lower values will probably mean good tires are
being condemned. Because tires can sometimes become temporarily flat-spotted, which will affect
force variation, it is important that the vehicle be driven at least 16 km (10 mi) prior to measuring.
Tire pressure must also be adjusted to the usage pressure on the vehicle's tire placard prior to
measuring.
Most GM vehicles will tolerate radial force variation up to these levels. However, some vehicles are
more sensitive, and may require lower levels. Also, there are other tire parameters that equipment
such as the Hunter GSP9700 cannot measure that may be a factor. In such cases, TAC should be
contacted for further instructions.
Important
- When mounting a GM wheel to a wheel balancer/force variation machine, always use the wheel's
center pilot hole. This is the primary centering mechanism on all GM wheels; the bolt holes are
secondary. Usually a back cone method to the machine should be used. For added accuracy and
repeatability, a flange plate should be used to clamp the wheel onto the cone and machine. This
system is offered by all balancer manufacturers in GM's dealer program.
- Any type of service equipment that removes tread rubber by grinding, buffing or truing is NOT
recommended, and may void the tire warranty. However, tires may have been ground by the tire
company as part of their tire manufacturing process. This is a legitimate procedure.
Steering Wheel Shake Worksheet
When diagnosing vibration concerns, use the following worksheet in conjunction with the
appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > Customer Interest: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire Radial Force Variation
(RFV) > Page 7825
Refer to the appropriate section of SI for specifications and repair procedures that are related to the
vibration concern.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > Customer Interest: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low Tire/Leaking Cast
Aluminum Wheels
Wheels: Customer Interest Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels
TECHNICAL
Bulletin No.: 05-03-10-003F
Date: April 27, 2010
Subject: Low Tire Pressure, Leaking Cast Aluminum Wheels (Repair with Adhesive Sealant)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2010 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X with Cast Aluminum Wheels
Supercede: This bulletin is being revised to update the model years and the bulletin reference
information. Please discard Corporate Bulletin Number 05-03-10-003E (Section 03 - Suspension).
Condition
Some customers may comment on a low tire pressure condition.
Diagnosis of the low tire pressure condition indicates an air leak through the cast aluminum wheel.
Cause
Porosity in the cast aluminum wheel may be the cause.
Notice
This bulletin specifically addresses issues related to the wheel casting that may result in an air
leak. For issues related to corrosion of the wheel in service, please refer to Corporate Bulletin
Number 08-03-10-006C - Tire Slowly Goes Flat, Tire Air Loss, Low Tire Pressure Warning Light
Illuminated, Aluminum Wheel Bead Seat Corrosion (Clean and Resurface Wheel Bead Seat).
Correction
1. Remove the tire and wheel assembly from the vehicle. Refer to the appropriate service
procedure in SI. 2. Locate the leaking area by inflating the tire to 276 kPa (40 psi) and dipping the
tire/wheel assembly in a water bath, or use a spray bottle with soap
and water to locate the specific leak location.
Important
- If the porosity leak is located in the bead area of the aluminum rim (where the tire meets the rim),
the wheel should be replaced.
- If two or more leaks are located on one wheel, the wheel should be replaced.
3. If air bubbles are observed, mark the location.
- If the leak location is on the tire/rubber area, refer to Corporate Bulletin Number 04-03-10-001F Tire Puncture Repair Procedures for All Cars and Light Duty Trucks.
- If the leak is located on the aluminum wheel area, continue with the next step.
4. Inscribe a mark on the tire at the valve stem in order to indicate the orientation of the tire to the
wheel. 5. Dismount the tire from the wheel. Refer to Tire Mounting and Dismounting. 6. Remove
the tire pressure sensor. Refer to Tire Pressure Sensor removal procedure in SI. 7. Scuff the
INSIDE rim surface at the leak area with #80 grit paper and clean the area with general purpose
cleaner, such as 3M(R) General Purpose
Adhesive Cleaner, P/N 08984, or equivalent.
8. Apply a 3 mm (0.12 in) thick layer of Silicone - Adhesive/Sealant, P/N 12378478 (in Canada, use
88900041), or equivalent, to the leak area. 9. Allow for the adhesive/sealant to dry.
Notice Caution must be used when mounting the tire so as not to damage the sealer. Damaging
the repair area may result in an air leak.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > Customer Interest: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low Tire/Leaking Cast
Aluminum Wheels > Page 7830
10. Align the inscribed mark on the tire with the valve stem on the wheel. 11. Reinstall the Tire
Pressure Sensor. Refer to Tire Pressure Sensor installation procedure in SI. 12. Mount the tire on
the wheel. Refer to Tire Mounting and Dismounting. 13. Pressurize the tire to 276 kPa (40 psi) and
inspect for leaks. 14. Adjust tire pressure to meet the placard specification. 15. Balance the
tire/wheel assembly. Refer to Tire and Wheel Assembly Balancing - Off-Vehicle. 16. Install the tire
and wheel assembly onto the vehicle. Refer to the appropriate service procedure in SI.
Parts Information
Warranty Information (excluding Saab U.S. Models)
Important The Silicone - Adhesive/Sealant comes in a case quantity of six. ONLY charge warranty
one tube of adhesive/sealant per wheel repair.
For vehicles repaired under warranty, use:
One leak repair per wheel.
Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use the table above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome
Wheel Staining/Pitting/Corrosion
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Staining/Pitting/Corrosion
INFORMATION
Bulletin No.: 00-03-10-002F
Date: April 21, 2011
Subject: Chemical Staining, Pitting, Corrosion and/or Spotted Appearance of Chromed Aluminum
Wheels
Models:
2012 and Prior GM Cars and Trucks
Supercede: This bulletin is being revised to update model years, suggest additional restorative
products and add additional corrosion information. Please discard Corporate Bulletin Number
00-03-10-002E (Section 03 - Suspension). Important You may give a copy of this bulletin to the
customer.
What is Chemical Staining of Chrome Wheels? Figure 1
Chemical staining in most cases results from acid based cleaners (refer to Figure 1 for an
example). These stains are frequently milky, black, or greenish in appearance. They result from
using cleaning solutions that contain acids on chrome wheels. Soap and water is usually sufficient
to clean wheels.
If the customer insists on using a wheel cleaner they should only use one that specifically states
that it is safe for chromed wheels and does not contain anything in the following list. (Dealers
should also survey any products they use during prep or normal cleaning of stock units for these
chemicals.)
- Ammonium Bifluoride (fluoride source for dissolution of chrome)
- Hydrofluoric Acid (directly dissolves chrome)
- Hydrochloric Acid (directly dissolves chrome)
- Sodium Dodecylbenzenesulfonic Acid
- Sulfamic Acid
- Phosphoric Acid
- Hydroxyacetic Acid
Notice
Many wheel cleaner instructions advise to take care to avoid contact with painted surfaces. Most
customers think of painted surfaces as the fenders, quarter panels and other exterior sheet metal.
Many vehicles have painted brake calipers. Acidic wheel cleaners may craze, crack, or discolor the
paint on the brake calipers. Damage from wheel cleaners is not covered under the vehicle new car
warranty. Soap and water applied with a soft brush is usually all that is required to clean the
calipers.
Whenever any wheel cleaner is used, it must be THOROUGHLY rinsed off of the wheel with clean,
clear water. Special care must be taken to rinse under the hub cap, balance weights, wheel nuts,
lug nut caps, between the wheel cladding and off the back side of the wheel. Wheels returned to
the Warranty Parts Center (WPC) that exhibit damage from wheel cleaners most often have the
damage around and under the wheel weight where the cleaner was incompletely flushed away.
Notice
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome
Wheel Staining/Pitting/Corrosion > Page 7836
Do not use cleaning solutions that contain hydrofluoric, oxalic and most other acids on chrome
wheels (or any wheels).
If the customer is unsure of the chemical make-up of a particular wheel cleaner, it should be
avoided.
For wheels showing signs of milky staining from acidic cleaners, refer to Customer Assistance and
Instructions below.
Warranty of Stained Chrome Wheels
Stained wheels are not warrantable. Most acid based cleaners will permanently stain chrome
wheels. Follow-up with dealers has confirmed that such cleaners were used on wheels that were
returned to the Warranty Parts Center (WPC). Any stained wheels received by the WPC will be
charged back to the dealership. To assist the customer, refer to Customer Assistance and
Instructions below.
Pitting or Spotted Appearance of Chrome Wheels Figure 2
A second type or staining or finish disturbance may result from road chemicals, such as calcium
chloride used for dust control of unpaved roads. The staining will look like small pitting (refer to
Figure 2). This staining will usually be on the leading edges of each wheel spoke, but may be
uniformly distributed. If a vehicle must be operated under such conditions, the chrome wheels
should be washed with mild soap and water and thoroughly rinsed as soon as conveniently
possible.
Important Road chemicals, such as calcium chloride used for dust control of unpaved roads, can
also stain chrome wheels. The staining will look like small pitting. This staining will usually be on
the leading edges of each wheel spoke. This is explained by the vehicle traveling in the forward
direction while being splashed by the road chemical. If a vehicle must be operated under such
conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed
as soon as conveniently possible.
Warranty of Pitted or Spotted Chrome Wheels
Wheels returned with pitting or spotting as a result of road chemicals may be replaced one time.
Damage resulting from contact with these applied road chemicals is corrosive to the wheels finish
and may cause damage if the wheels are not kept clean.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean if they are operating the vehicle in an area that
applies calcium chloride or other dust controlling chemicals! "GM of Canada" dealers require prior
approval by the District Manager - Customer Care and Service Process (DM-CCSP).
"Stardust" Corrosion of Chrome Wheels Figure 3
A third type of finish disturbance results from prolonged exposure to brake dust and resultant
penetration of brake dust through the chrome. As brakes are applied hot particles of brake material
are thrown off and tend to be forced through the leading edge of the wheel spoke windows by
airflow. These
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome
Wheel Staining/Pitting/Corrosion > Page 7837
hot particles embed themselves in the chrome layer and create a small pit. If the material is allowed
to sit on the wheel while it is exposed to moisture or salt, it will corrode the wheel beneath the
chrome leaving a pit or small blister in the chrome.
Heavy brake dust build-up should be removed from wheels by using GM Chrome Cleaner and
Polish, P/N 1050173 (in Canada use 10953013). For moderate cleaning, light brake dust build-up
or water spots use GM Swirl Remover Polish, P/N 12377965 (in Canada, use Meguiars
Plast-X(TM) Clear Plastic Cleaner and Polish #G12310C**). After cleaning, the wheel should be
waxed using GM Cleaner Wax, P/N 12377966 (in Canada, use Meguiars Cleaner Wax
#M0616C**), which will help protect the wheel from brake dust and reduce adhesion of any brake
dust that gets on the wheel surface. For general maintenance cleaning, PEEK Metal Polish† may
be used. It will clean and shine the chrome and leave behind a wax coating that may help protect
the finish.
Warranty of Stardust Corroded Chrome Wheels
Wheels returned with pitting or spotting as a result of neglect and brake dust build-up may be
replaced one time.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean and free of prolonged exposure to brake dust
build-up. "GM of Canada" dealers require prior approval by the District Manager - Customer Care
and Service Process (DM-CCSP).
Customer Assistance and Instructions
GM has looked for ways customers may improve the appearance of wheels damaged by acidic
cleaners. The following product and procedure has been found to dramatically improve the
appearance of stained wheels. For wheels that have milky stains caused by acidic cleaners try the
following:
Notice
THE 3M CHROME AND METAL POLISH REQUIRED FOR THIS PROCEDURE IS AN
EXTREMELY AGGRESSIVE POLISH/CLEANER. THE WHEELS MUST BE CLEANED BEFORE
APPLICATION TO AVOID SCRATCHING THE WHEEL SURFACE. THIS PRODUCT WILL
REDUCE THE THICKNESS OF THE CHROME PLATING ON THE WHEEL AND IF USED
INCORRECTLY OR EXCESSIVELY MAY REMOVE THE CHROME PLATING ALL TOGETHER,
EXPOSING A LESS BRIGHT AND BRASSY COLORED SUB-LAYER. FOLLOW INSTRUCTIONS
EXACTLY.
1. Wash the wheels with vigorously with soap and water. This step will clean and may reduce
wheel staining. Flood all areas of the wheel with water
to rinse.
2. Dry the wheels completely.
Notice Begin with a small section of the wheel and with light pressure buff off polish and examine
results. ONLY apply and rub with sufficient force and time to remove enough staining that you are
satisfied with the results. Some wheels may be stained to the extent that you may only achieve a
50% improvement while others may be able to be restored to the original lustre. IN ALL CASES,
only apply until the results are satisfactory.
3. Apply 3M Chrome and Metal Polish #39527* with a clean terry cloth towel. As you apply the
polish, the staining will be diminished. 4. When dry, buff off the polish with a clean portion of the
towel. 5. Repeat application of the 3M Chrome and Metal Polish until satisfied with the results. If
continued applications fail to improve the appearance
further discontinue use.
This procedure will improve the appearance of the wheels and may, with repeated applications,
restore the finish dramatically. For wheels that exhibit spotting from road chemicals the above
procedure may marginally improve the condition but will not restore the finish or remove the pitting.
In this type of staining the wheel finish has actually been removed in spots and no manner of
cleaning will restore the finish.
†*We believe this source and their products to be reliable. There may be additional manufacturers
of such products/materials. General Motors does not endorse, indicate any preference for or
assume any responsibility for the products or material from this firm or for any such items that may
be available from other sources.
Parts Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome
Wheel Staining/Pitting/Corrosion > Page 7838
*This product is currently available from 3M. To obtain information for your local retail location
please call 3M at 1-888-364-3577.
**This product is currently available from Meguiars (Canada). To obtain information for your local
retail location please call Meguiars at 1-800-347-5700 or at www.meguiarscanada.com.
^ This product is currently available from Tri-Peek International. To obtain information for your local
retail location please call Tri-Peek at
1-877-615-4272 or at www.tripeek.com.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires Refinishing Aluminum Wheels
Wheels: All Technical Service Bulletins Wheels/Tires - Refinishing Aluminum Wheels
INFORMATION
Bulletin No.: 99-08-51-007E
Date: March 17, 2011
Subject: Refinishing Aluminum Wheels
Models:
2012 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add additional model years. Please discard Corporate
Bulletin Number 99-08-51-007D (Section 08 - Body and Accessories).
This bulletin updates General Motor's position on refinishing aluminum wheels. GM does not
endorse any repairs that involve welding, bending, straightening or re-machining. Only cosmetic
refinishing of the wheel's coatings, using recommended procedures, is allowed.
Evaluating Damage
In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion,
scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be
sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the
wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been
refinished by an outside company must be returned to the same vehicle. The Dealer must record
the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to
Refinisher's Responsibility - Outside Company later in this bulletin.
Aluminum Wheel Refinishing Recommendations
- Chrome-plated aluminum wheels Re-plating these wheels is not recommended.
- Polished aluminum wheels These wheels have a polyester or acrylic clearcoat on them. If the
clearcoat is damaged, refinishing is possible. However, the required refinishing process cannot be
performed in the dealer environment. Refer to Refinisher's Responsibility - Outside Company later
in this bulletin.
- Painted aluminum wheels These wheels are painted using a primer, color coat, and clearcoat
procedure. If the paint is damaged, refinishing is possible. As with polished wheels, all original
coatings must be removed first. Media blasting is recommended. Refer to GM Aluminum
Refinishing Bulletin #53-17-03A for the re-painting of this type of wheel.
- Bright, machined aluminum wheels These wheels have a polyester or acrylic clearcoat on them.
In some cases, the recessed "pocket" areas of the wheel may be painted. Surface refinishing is
possible. The wheel must be totally stripped by media blasting or other suitable means. The wheel
should be resurfaced by using a sanding process rather than a machining process. This allows the
least amount of material to be removed.
Important Do not use any re-machining process that removes aluminum. This could affect the
dimensions and function of the wheel.
Painting is an option to re-clearcoating polished and bright machined aluminum wheels. Paint will
better mask any surface imperfections and is somewhat more durable than clearcoat alone. GM
recommends using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle
SILVER WA9967 for a very bright look. As an option, the body color may also be used. When using
any of the painting options, it is recommended that all four wheels be refinished in order to maintain
color uniformity. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for specific procedures
and product recommendations.
Refinisher's Responsibility - Outside Company
Important Some outside companies are offering wheel refinishing services. Such refinished wheels
will be permanently marked by the refinisher and are warranted by the refinisher. Any process that
re-machines or otherwise re-manufactures the wheel should not be used.
A refinisher's responsibility includes inspecting for cracks using the Zyglo system or the equivalent.
Any cracked wheels must not be refinished. No welding, hammering or reforming of any kind is
allowed. The wheel ID must be recorded and follow the wheel throughout the process in order to
assure that the same wheel is returned. A plastic media blast may be used for clean up of the
wheel. Hand and/or lathe sanding of the machined surface and the wheel window is allowed.
Material removal, though, must be kept to a minimum. Re-machining of the wheel is not allowed.
Paint and/or clear coat must not be present on the following surfaces: the nut chamfers, the wheel
mounting surfaces and the wheel pilot hole. The refinisher must permanently ID stamp the wheel
and warrant the painted/clearcoated surfaces for a minimum of one year or the remainder of the
new vehicle warranty, whichever is
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires Refinishing Aluminum Wheels > Page 7843
longer.
Important Whenever a wheel is refinished, the mounting surface and the wheel nut contact
surfaces must not be painted or clearcoated. Coating these surfaces could affect the wheel nut
torque.
When re-mounting a tire on an aluminum wheel, coated balance weights must be used in order to
reduce the chance of future cosmetic damage.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions
Wheels: All Technical Service Bulletins Wheels - Changing Procedures/Precautions
INFORMATION
Bulletin No.: 06-03-10-010A
Date: June 09, 2010
Subject: Information on Proper Wheel Changing Procedures and Cautions
Models:
2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER Models 2005-2009 Saab
9-7X 2005-2009 Saturn Vehicles
Attention:
Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel
Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and
reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel
installation. Always refer to SI for wheel lug nut torque specifications and complete jacking
instructions for safe wheel changing.
Supercede: This bulletin is being revised to include the 2011 model year and update the available
special tool list. Please discard Corporate Bulletin Number 06-03-10-010 (Section 03 Suspension).
Frequency of Wheel Changes - Marketplace Driven
Just a few years ago, the increasing longevity of tires along with greater resistance to punctures
had greatly reduced the number of times wheels were removed to basically required tire rotation
intervals. Today with the booming business in accessory wheels/special application tires (such as
winter tires), consumers are having tire/wheel assemblies removed - replaced - or installed more
than ever. With this increased activity, it opens up more of a chance for error on the part of the
technician. This bulletin will review a few of the common concerns and mistakes to make yourself
aware of.
Proper Servicing Starts With the Right Tools
The following tools have been made available to assist in proper wheel and tire removal and
installation.
- J 41013 Rotor Resurfacing Kit (or equivalent)
- J 42450-A Wheel Hub Resurfacing Kit (or equivalent)
Corroded Surfaces
One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle.
Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened
wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed
away from water splash. This action may result in clearance at the mating surface of the wheel and
an under-torqued condition.
Caution
Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or
brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting
surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is
moving, possibly resulting in a loss of control or personal injury.
Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If
corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding
pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating
surface.
The J 41013 (or equivalent) can be used to clean the following surfaces:
- The hub mounting surface
- The brake rotor mounting surface
- The wheel mounting surface
Use the J 42450-A (or equivalent) to clean around the base of the studs and the hub.
Lubricants, Grease and Fluids
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Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 7848
Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in
removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to
installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper
readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY.
Notice
Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or
drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to
clean, dry wheel studs and surfaces ONLY. Beginning with 2011 model year vehicles, put a light
coating of grease, GM P/N 1051344 (in Canada, P/N 9930370), on the inner surface of the wheel
pilot hole to prevent wheel seizure to the axle or bearing hub.
Wheel Stud and Lug Nut Damage
Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse.
You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not
retain properly, yet give the impression of fully tightening. Always inspect and replace any
component suspected of damage.
Tip
Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged
BEFORE tightening the nut.
Important If the vehicle has directional tread tires, verify the directional arrow on the outboard side
of the tire is pointing in the direction of forward rotation.
Wheel Nut Tightening and Torque
Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid
additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown
for each vehicle in SI. Always observe the proper wheel nut tightening sequence as shown below in
order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off
center resulting in vibration.
The Most Important Service You Provide
While the above information is well known, and wheel removal so common, technicians run the risk
of becoming complacent on this very important
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 7849
service operation. A simple distraction or time constraint that rushes the job may result in personal
injury if the greatest of care is not exercised. Make it a habit to double check your work and to
always side with caution when installing wheels.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire
Radial Force Variation (RFV)
Wheels: All Technical Service Bulletins Wheels/Tires - Tire Radial Force Variation (RFV)
INFORMATION
Bulletin No.: 00-03-10-006F
Date: May 04, 2010
Subject: Information on Tire Radial Force Variation (RFV)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3 2009
and Prior Saab 9-7X 2000-2005 Saturn L Series 2003-2007 Saturn ION
Supercede: This bulletin is being revised to considerably expand the available information on
Radial Force Variation (RFV) and should be reviewed in whole. Please discard Corporate Bulletin
Number 00-03-10-006E (Section 03 - Suspension).
Important
- Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven
a minimum of 16 km (10 mi) to ensure removal of any flat-spotting. Refer to Corporate Bulletin
Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original Equipment Tires.
- Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel
assemblies for each vehicle.
The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation
measurement equipment, such as the Hunter GSP9700. This type of equipment can be a valuable
tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force
variation is highway speed shake on smooth roads.
Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out
of round and tire force variation. These three conditions are not necessarily related. All three
conditions must be addressed.
Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle,
two plane dynamic wheel balancers are readily available and can accurately correct any
imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer,
and proper balance weights, are all factors required for a quality balance. However, a perfectly
balanced tire/wheel assembly can still be "oval shaped" and cause a vibration.
Before balancing, perform the following procedures.
Tire and Wheel Diagnosis
1. Set the tire pressure to the placard values. 2. With the vehicle raised, ensure the wheels are
centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while
shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick.
3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and
correct as necessary:
- Missing balance weights
- Bent rim flange
- Irregular tire wear
- Incomplete bead seating
- Tire irregularities (including pressure settings)
- Mud/ice build-up in wheel
- Stones in the tire tread
- Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to
diagnosing a smooth road shake condition.
4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a
sufficient distance on a known, smooth road
surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes
are applied lightly and the pulsation felt in the steering wheel increases, refer to the Brakes section
of the service manual that deals with brake-induced pulsation. If you can start to hear the vibration
as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order
(one pulse per propshaft revolution) driveline vibration. Driveline first order vibrations are high
enough in frequency that most humans can start to hear them at highway speeds, but are too high
to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment.
If the vehicle exhibits this low boom and the booming pulses in-and-out on a regular basis (like a
throbbing), chances are good that the vehicle could have driveline vibration. This type
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire
Radial Force Variation (RFV) > Page 7854
of vibration is normally felt more in the "seat of the pants" than the steering wheel.
5. Next, record the Hertz (Hz) reading as displayed by the EVA onto the tire data worksheet found
at the end of this bulletin. This should be done
after a tire break-in period of at least 16 km (10 mi) at 72 km/h (45 mph) or greater, in order to
eliminate any possible tire flat-spotting. This reading confirms what the vehicle vibration frequency
is prior to vehicle service and documents the amount of improvement occurring as the result of the
various steps taken to repair. Completing the Steering Wheel Shake Worksheet below is required.
A copy of the completed worksheet must be saved with the R.O. and a copy included with any
parts returned to the Warranty Parts Center for analysis. A reading of 35 to 50 Hz typically
indicates a first order propshaft vibration. If this is the situation, refer to Corporate Bulletin Number
08-07-30-044D. Generally, a reading between 10 and 20 Hz indicates a tire/wheel vibration and if
this is the reading obtained, continue using this bulletin. If the tire 1st order vibration goes away
and stays away during this evaluation, the cause is likely tire flat-spotting. Tire flat-spotting vibration
may come and go at any speed over 72 km/h (45 mph) during the first 10 minutes of operation, if
vibration continues after 10 minutes of driving at speeds greater than 72 km/h (45 mph), tire
flat-spotting can be ruled out as the cause for vibration.
6. If flat-spotting is the cause, provide the explanation that this has occurred due to the vehicle
being parked for long periods of time and that the
nature of the tire is to take a set. Refer to Corporate Bulletin Number 03-03-10-007E: Information
on Tire/Wheel Characteristics (Vibration, Balance, Shake, Flat Spotting) of GM Original Equipment
Tires.
7. If the road test indicates a shake/vibration exists, check the imbalance of each tire/wheel
assembly on a known, calibrated, off-car dynamic
balancer.Make sure the mounting surface of the wheel and the surface of the balancer are
absolutely clean and free of debris. Be sure to chose the proper cone/collet for the wheel, and
always use the pilot bore for centering. Never center the wheel using the hub-cap bore since it is
not a precision machined surface. If any assembly calls for more than 1/4 ounce on either rim
flange, remove all balance weights and rebalance to as close to zero as possible. If you can see
the vibration (along with feeling it) in the steering wheel (driving straight without your hands on the
wheel), it is very likely to be a tire/wheel first order (one pulse per revolution) disturbance. First
order disturbances can be caused by imbalance as well as non-uniformities in tires, wheels or
hubs. This first order frequency is too low for a human to hear, but if the amplitude is high enough,
it can be seen.
If a vibration or shake still exists after balancing, any out of round conditions, of the wheel, and
force variation conditions of the tire, must be addressed. Equipment such as the Hunter GSP9700
can address both (it is also a wheel balancer).
Tire radial force vibration (RFV) can be defined as the amount of stiffness variation the tire will
produce in one revolution under a constant load. Radial force variation is what the vehicle feels
because the load (weight) of the vehicle is always on the tires. Although free runout of tires (not
under load) is not always a good indicator of a smooth ride, it is critical that total tire/wheel
assembly runout be within specification.
Equipment such as the Hunter GSP9700 loads the tire, similar to on the vehicle, and measures
radial force variation of the tire/wheel assembly. Note that the wheel is affecting the tire's RFV
measurement at this point. To isolate the wheel, its runout must be measured. This can be easily
done on the Hunter, without the need to set up dial indicators. If the wheel meets the runout
specification, the tire's RFV can then be addressed.
After measuring the tire/wheel assembly under load, and the wheel alone, the machine then
calculates (predicts) the radial force variation of the tire. However, because this is a prediction that
can include mounting inaccuracies, and the load wheel is much smaller in diameter than used in
tire production, this type of service equipment should NOT be used to audit new tires. Rather, it
should be used as a service diagnostic tool to minimize radial force variation of the tire/wheel
assembly.
Equipment such as the Hunter GSP9700 does an excellent job of measuring wheel runout, and of
finding the low point of the wheel (for runout) and the high point of the tire (for radial force
variation). This allows the tire to be matched mounted to the wheel for lowest tire/wheel assembly
force variation.
The machine will simplify this process into easy steps. The following assembly radial force variation
numbers should be used as a guide:
When measuring RFV and match mounting tires perform the following steps.
Measuring Wheel Runout and Assembly Radial Force Variation
Important The completed worksheet at the end of this bulletin must be attached to the hard copy of
the repair order.
- Measure radial force variation and radial runout.
- If a road force/balancing machine is used, record the radial force variation (RFV) on the
worksheet at the end of this bulletin. It may be of benefit to have the lowest RFV assembly to the
front left corner. If the machine is not available and the EVA data suggests there is an issue, swap
the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem
still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those
tires onto the subject vehicle.
- If a runout/balancing machine is used, record the radial runout of the tire/wheel assemblies on the
worksheet at the end of this bulletin. If one or more of the tire/wheel assemblies are more than.040
in (1.02 mm), match mount the tire to the wheel to get below.040 in (1.02 mm). For sensitive
customers, readings of 0.030 inch (0.76 mm) or less are preferable, it may also be of benefit to
have the lowest runout assembly to the front left corner. If the machine is not available and the
EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the
back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do
not exhibit the same frequency and swap those tires
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire
Radial Force Variation (RFV) > Page 7855
onto the subject vehicle.
- After match mounting, the tire/wheel assembly must be rebalanced.
If match mounting tires to in-spec wheels produces assembly values higher than these, tire
replacement may be necessary. Replacing tires at lower values will probably mean good tires are
being condemned. Because tires can sometimes become temporarily flat-spotted, which will affect
force variation, it is important that the vehicle be driven at least 16 km (10 mi) prior to measuring.
Tire pressure must also be adjusted to the usage pressure on the vehicle's tire placard prior to
measuring.
Most GM vehicles will tolerate radial force variation up to these levels. However, some vehicles are
more sensitive, and may require lower levels. Also, there are other tire parameters that equipment
such as the Hunter GSP9700 cannot measure that may be a factor. In such cases, TAC should be
contacted for further instructions.
Important
- When mounting a GM wheel to a wheel balancer/force variation machine, always use the wheel's
center pilot hole. This is the primary centering mechanism on all GM wheels; the bolt holes are
secondary. Usually a back cone method to the machine should be used. For added accuracy and
repeatability, a flange plate should be used to clamp the wheel onto the cone and machine. This
system is offered by all balancer manufacturers in GM's dealer program.
- Any type of service equipment that removes tread rubber by grinding, buffing or truing is NOT
recommended, and may void the tire warranty. However, tires may have been ground by the tire
company as part of their tire manufacturing process. This is a legitimate procedure.
Steering Wheel Shake Worksheet
When diagnosing vibration concerns, use the following worksheet in conjunction with the
appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 00-03-10-006F > May > 10 > Wheels/Tires - Tire
Radial Force Variation (RFV) > Page 7856
Refer to the appropriate section of SI for specifications and repair procedures that are related to the
vibration concern.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low
Tire/Leaking Cast Aluminum Wheels
Wheels: All Technical Service Bulletins Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels
TECHNICAL
Bulletin No.: 05-03-10-003F
Date: April 27, 2010
Subject: Low Tire Pressure, Leaking Cast Aluminum Wheels (Repair with Adhesive Sealant)
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2010 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X with Cast Aluminum Wheels
Supercede: This bulletin is being revised to update the model years and the bulletin reference
information. Please discard Corporate Bulletin Number 05-03-10-003E (Section 03 - Suspension).
Condition
Some customers may comment on a low tire pressure condition.
Diagnosis of the low tire pressure condition indicates an air leak through the cast aluminum wheel.
Cause
Porosity in the cast aluminum wheel may be the cause.
Notice
This bulletin specifically addresses issues related to the wheel casting that may result in an air
leak. For issues related to corrosion of the wheel in service, please refer to Corporate Bulletin
Number 08-03-10-006C - Tire Slowly Goes Flat, Tire Air Loss, Low Tire Pressure Warning Light
Illuminated, Aluminum Wheel Bead Seat Corrosion (Clean and Resurface Wheel Bead Seat).
Correction
1. Remove the tire and wheel assembly from the vehicle. Refer to the appropriate service
procedure in SI. 2. Locate the leaking area by inflating the tire to 276 kPa (40 psi) and dipping the
tire/wheel assembly in a water bath, or use a spray bottle with soap
and water to locate the specific leak location.
Important
- If the porosity leak is located in the bead area of the aluminum rim (where the tire meets the rim),
the wheel should be replaced.
- If two or more leaks are located on one wheel, the wheel should be replaced.
3. If air bubbles are observed, mark the location.
- If the leak location is on the tire/rubber area, refer to Corporate Bulletin Number 04-03-10-001F Tire Puncture Repair Procedures for All Cars and Light Duty Trucks.
- If the leak is located on the aluminum wheel area, continue with the next step.
4. Inscribe a mark on the tire at the valve stem in order to indicate the orientation of the tire to the
wheel. 5. Dismount the tire from the wheel. Refer to Tire Mounting and Dismounting. 6. Remove
the tire pressure sensor. Refer to Tire Pressure Sensor removal procedure in SI. 7. Scuff the
INSIDE rim surface at the leak area with #80 grit paper and clean the area with general purpose
cleaner, such as 3M(R) General Purpose
Adhesive Cleaner, P/N 08984, or equivalent.
8. Apply a 3 mm (0.12 in) thick layer of Silicone - Adhesive/Sealant, P/N 12378478 (in Canada, use
88900041), or equivalent, to the leak area. 9. Allow for the adhesive/sealant to dry.
Notice Caution must be used when mounting the tire so as not to damage the sealer. Damaging
the repair area may result in an air leak.
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 05-03-10-003F > Apr > 10 > Tires/Wheels - Low
Tire/Leaking Cast Aluminum Wheels > Page 7861
10. Align the inscribed mark on the tire with the valve stem on the wheel. 11. Reinstall the Tire
Pressure Sensor. Refer to Tire Pressure Sensor installation procedure in SI. 12. Mount the tire on
the wheel. Refer to Tire Mounting and Dismounting. 13. Pressurize the tire to 276 kPa (40 psi) and
inspect for leaks. 14. Adjust tire pressure to meet the placard specification. 15. Balance the
tire/wheel assembly. Refer to Tire and Wheel Assembly Balancing - Off-Vehicle. 16. Install the tire
and wheel assembly onto the vehicle. Refer to the appropriate service procedure in SI.
Parts Information
Warranty Information (excluding Saab U.S. Models)
Important The Silicone - Adhesive/Sealant comes in a case quantity of six. ONLY charge warranty
one tube of adhesive/sealant per wheel repair.
For vehicles repaired under warranty, use:
One leak repair per wheel.
Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use the table above.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 04-03-10-012B > Feb > 08 > Wheels - Chrome
Wheel Brake Dust Accumulation/Pitting
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Brake Dust Accumulation/Pitting
Bulletin No.: 04-03-10-012B
Date: February 01, 2008
INFORMATION
Subject: Pitting and Brake Dust on Chrome wheels
Models: 2008 and Prior GM Passenger Cars and Trucks (including Saturn) 2008 and Prior
HUMMER H2, H3 2005-2008 Saab 9-7X
Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number
04-03-10-012A (Section 03 - Suspension).
Analysis of Returned Wheels
Chrome wheels returned under the New Vehicle Limited Warranty for pitting concerns have
recently been evaluated. This condition is usually most severe in the vent (or window) area of the
front wheels. This "pitting" may actually be brake dust that has been allowed to accumulate on the
wheel. The longer this accumulation builds up, the more difficult it is to remove.
Cleaning the Wheels
In all cases, the returned wheels could be cleaned to their original condition using GM Vehicle Care
Cleaner Wax, P/N 12377966 (in Canada, P/N 10952905). When using this product, you should
confine your treatment to the areas of the wheel that show evidence of the brake dust build-up.
This product is only for use on chromed steel or chromed aluminum wheels.
Parts Information
Warranty Information
Wheel replacement for this condition is NOT applicable under the terms of the New Vehicle Limited
Warranty.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 99-03-10-102 > Jun > 99 > Warranty - OE
Chrome Plated Aluminum Wheel ID
Wheels: All Technical Service Bulletins Warranty - OE Chrome Plated Aluminum Wheel ID
File In Section: 03 - Suspension
Bulletin No.: 99-03-10-102
Date: June, 1999
INFORMATION
Subject: Original Equipment Chrome Plated Aluminum Wheel Identification
Models: 1999 and Prior Passenger Cars and Light Duty Trucks
Chrome plated aluminum wheels have been returned to the Warranty Parts Center that are not the
original equipment (OE) components.
Original equipment chrome plated aluminum wheels can be identified by either a balance weight
clip retention groove (1) or a step (2) that is machined around both of the wheel's rim flanges. The
rim flanges (3) of painted original equipment aluminum wheels do not have a groove or a step.
Chrome plated aluminum wheels that do not have the wheel rim flange groove or step are
aftermarket chrome plated components and are NOT warrantable. Any aftermarket chrome wheels
received by the Warranty Parts Center will be charged back to the dealership.
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 72-05-05 > Aug > 97 > Warranty - Guidelines for
Using E0420 Wheel Replace
Wheels: All Technical Service Bulletins Warranty - Guidelines for Using E0420 Wheel Replace
File In Section: Warranty Administration
Bulletin No.: 72-05-05
Date: August, 1997
WARRANTY ADMINISTRATION
Subject: Guidelines for Using EO42O Wheel Replace
Models: 1989-98 Passenger Cars and Light Duty Trucks
The purpose of this bulletin is to provide service personnel with guidelines for using the above
subject labor operation.
Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the
following:
^ Aluminum Wheels (including chrome plated) with Porosity - Wheels that exhibit porosity should
be repaired as described in the vehicle service manual. Wheels should not be replaced without
wholesale approval.
^ Aluminum Wheels (except chrome plated) with a "Finish Defect" - Wheels that exhibit a defect in
the finish, (i.e., discoloration or surface degradation) should be refinished as described in the
Corporate Service Bulletin Number 53-17-03A released in May, 1996.
^ Chrome Wheels - Wheels that are chromed and found to have a finish defect can only be
replaced.
^ Aluminum and chrome wheels replaced under warranty will be subject to random part review and
inspection. Those wheels inspected and found not to be defective and/or should have been
repaired, will be subject to charge back.
Wheels damaged by normal wear, road hazards, car wash brushes, or other physical or chemical
damage are not eligible for warranty coverage.
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing
Technical Service Bulletin # 531703A Date: 960501
Aluminum Wheels - Refinishing
File In Section: 10 - Body
Bulletin No.: 53-17-03A
Date: May, 1996
INFORMATION
Subject: Aluminum Wheel Refinishing
Models: 1991-96 Passenger Cars and Trucks
This bulletin is being revised to delete the 1990 model year and add the 1996 model year. Please
discard Corporate Bulletin Number 53-17-03 (Section 10 - Body).
This bulletin supersedes and cancels all previous service bulletins concerning the refinishing of
aluminum wheels. The purpose of this service bulletin is to assist dealerships in repairing the
discoloration or surface degradation that has occurred on styled aluminum wheels.
This bulletin provides NEW PROCEDURES AND SPECIFIC MATERIALS for the refinishing of
painted aluminum wheels or aluminum wheels with discoloration or surface degradation.
Important:
THE RE-MACHINING OF ALUMINUM WHEELS IS NOT RECOMMENDED. THE RE-CLEAR
COATING OF ALUMINUM WHEELS IS NO LONGER RECOMMENDED DUE TO CONCERNS OF
REPAIR DURABILITY
The new procedure requires the wheel surface be plastic media blasted to remove old paint or
clear coat. CHEMICAL STRIPPERS ARE NOT RECOMMENDED.
Material Required
System 1: DuPont Products
3939-S Cleaning Solvent 615/616 Etching Primer URO 5000 Primer Surfacer IMRON 6000
Basecoat 3440-S IMRON Clear
System 2: PPG Products
DX533 Aluminum Cleaner DX503 Aluminum Conditioner DP Epoxy Primer Deltron Basecoat
(DBC) Concept 2001 Clear Acrylic Urethane
System 3: Spies Hecker
Permahyd Silicone Remover 7090 Permahyd 1:1 Primer 4070 Permahyd 2:1 Surfacer 5080
Permahyd Base Coat Series 280/285 Permahyd H.S. Clearcoat 8060
Color Selection
If the wheels being painted were previously clearcoated aluminum, we would recommend using
Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a
very bright look. As an option to the customer, you may also use body color. For color
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selection and verification, refer to your paint manufacturer's color book. On wheels that were
previous clearcoated aluminum it is recommended that all four wheels and their center caps be
refinished to maintain color uniformity.
Important:
THE PRODUCTS LISTED MUST BE USED AS A SYSTEM. DO NOT MIX OTHER
MANUFACTURERS' PRODUCT LINES WITH THE REQUIRED MATERIALS. PRODUCTS
LISTED IN THIS BULLETIN HAVE SHOWN THE REQUIRED REPAIR DURABILITY, AND
CURRENTLY ARE THE ONLY PAINT SYSTEMS THAT MEET GM SPECIFICATION
4350M-A336.
Procedures
1. Remove wheels from vehicle. Tires may remain mounted on wheels.
2. Remove balance weights and mark their location on tire.
3. Wipe excess grease, etc. from wheels with wax and grease remover.
4. Have wheels plastic media blasted to remove clearcoat. FOR FURTHER INFORMATION ON
MEDIA BLASTING IN YOUR AREA, CALL US TECHNOLOGIES INC., CONTACT DAVE
ROSENBURG AT 1-800-634-9185.
Caution:
IT IS MANDATORY THAT ADEQUATE RESPIRATORY PROTECTION BE WORN. EXAMPLES
OF SUCH PROTECTION ARE: AIR LINE RESPIRATORS WITH FULL HOOD OR HALF MASK. IF
NOT AVAILABLE, USE A VAPOR/PARTICULATE RESPIRATOR THAT RESPIRATOR
MANUFACTURER RECOMMENDS AS EFFECTIVE FOR ISOCYANATE VAPOR AND MISTS
(UNLESS LOCAL REGULATIONS PREVAIL).
5. Painting Process
a. Refer to Attachments 1-3 for each System's individual formula and process.
b. After following the specific System's individual formula and process, follow these steps:
6. Unmask wheels.
7. Clean all wheel mounting surface of any corrosion, overspray, or dirt.
8. Install new coated balance weights, at marked locations.
9. Replace wheels on vehicle.
10. USE A TORQUE STICK ON AN IMPACT WRENCH, OR A TORQUE WRENCH TO
CONSISTENTLY AND UNIFORMLY FASTEN THE WHEEL TO THE SPECIFIED TORQUE FOR
THE VEHICLE. THE STAR PATTERN MUST BE FOLLOWED.
Important:
TORQUE STICKS MUST BE USED ANY TIME AN IMPACT WRENCH IS USED TO TIGHTEN
WHEEL NUTS.
Warranty Information
For vehicles repaired under warranty, use as shown.
Attachment 1 - DuPont Products
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Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing > Page 7879
Painting Process
System: Dupont Products
Paint Color Information: Corsican Silver WA EQ9283 Dupont # C9143, Sparkle Silver WA9967
Dupont # C9339
1. Wipe wheel with cleaning solvent: 3939-S, 3949-S or 3900-S.
2. Mask off tires.
Important:
3. Mask off all wheel mounting surfaces and wheel mount surfaces.
4. Apply two coats of 615/616-S etching primer to wheel allowing 10 minutes flash between coats.
Allow to dry for 30 minutes before applying primer coat.
5. Apply URO 5000 primer 1220/193-S + accelerator 389-S using two coats at 65-70 PSI at the
gun. Allow 12-15 minutes between coats. Force bake 30 minutes at 140°F (60°C).
6. Scuff sand using green Scotch-Brite pad.
7. Solvent wipe before top coating.
8. Apply IMRON 6000 base coat to wheel. 2-3 coats to hiding at 60-70 PSI allowing to flash
between coats. Base coat needs to dry 20-30 minutes before clearcoat is applied.
9. Apply 3440-S clearcoat to wheel using two coats at 60-70 PSI. Flash 10-15 minutes between
coats. 389-S can be used in basecoat and clearcoat to give faster set up times.
10. Allow overnight dry before reassemble. Can be baked for 30 minutes at 140°F (60°C).
Attachment 2 - PPG Products
Painting Process: PPG System
Paint Color Information: Corsican Silver WAEQ9283; PPG # DBC-3531, Sparkle Silver WA9967;
PPG # 35367
1. Wash entire wheel with aluminum cleaner DX533, mix 1:3 with water. Allow to react 2-3 minutes
and rinse thoroughly.
2. Wash entire wheel with aluminum conditioner DX5O3 straight from the container. Allow to react
2-3 minutes until pale gold or tan color develops. Rinse thoroughly and dry.
3. Mask off tires.
Important:
4. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
5. Apply 1-2 coats of DP Primer and allow to flash for 15-20 minutes.
6. Apply 2-3 coats of Deltron Basecoat (DBC) and allow to flash 20 minutes after the final coat.
7. Apply two (2) wet coats of Concept 2001 Acrylic urethane.
8. Flash 20 minutes and bake 140°F (60°C) for 30 minutes.
For more information contact your PPG Jobber.
Attachment 3 - Spies Hecker
Painting Process: Spies Hecker System
Paint Color Information: Corsican Silver AWEQ9283; SH-72913, Sparkle Silver WA9967;
SH-71912
1. Clean with Permahyd Silicone Remover 7090.
2. Mask off tires.
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Technical Service Bulletins > All Technical Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing > Page 7880
Important:
3. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
4. Apply 1-1/2 coats of Permahyd 1:1 Primer 4070. Mix 1:1 with Permahyd Hardener 3070 as per
TDS.
5. Allow to flash for 30 minutes.
6. Apply two (2) coats of Permahyd 2:1 Surfacer 5080. Mix 2:1 with Permahyd Hardener 3071 as
per TDS.
7. Bake for 60 minutes at 140°F (60°C) or allow to flash for 3 hours at 68°F (20°C).
8. Apply Permahyd Base Coat Series 280/285 as per TDS.
9. Allow to flash 10 to 15 minutes.
10. Apply 1 to 2 coats of Permacron High Solid Clear Coat 8060 as per TDS.
11. Allow to flash 10 minutes. Then bake at 140°F (60°C) for 40 minutes.
For more information, contact your SPIES HECKER Jobber.
We believe these sources and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Staining/Pitting/Corrosion
INFORMATION
Bulletin No.: 00-03-10-002F
Date: April 21, 2011
Subject: Chemical Staining, Pitting, Corrosion and/or Spotted Appearance of Chromed Aluminum
Wheels
Models:
2012 and Prior GM Cars and Trucks
Supercede: This bulletin is being revised to update model years, suggest additional restorative
products and add additional corrosion information. Please discard Corporate Bulletin Number
00-03-10-002E (Section 03 - Suspension). Important You may give a copy of this bulletin to the
customer.
What is Chemical Staining of Chrome Wheels? Figure 1
Chemical staining in most cases results from acid based cleaners (refer to Figure 1 for an
example). These stains are frequently milky, black, or greenish in appearance. They result from
using cleaning solutions that contain acids on chrome wheels. Soap and water is usually sufficient
to clean wheels.
If the customer insists on using a wheel cleaner they should only use one that specifically states
that it is safe for chromed wheels and does not contain anything in the following list. (Dealers
should also survey any products they use during prep or normal cleaning of stock units for these
chemicals.)
- Ammonium Bifluoride (fluoride source for dissolution of chrome)
- Hydrofluoric Acid (directly dissolves chrome)
- Hydrochloric Acid (directly dissolves chrome)
- Sodium Dodecylbenzenesulfonic Acid
- Sulfamic Acid
- Phosphoric Acid
- Hydroxyacetic Acid
Notice
Many wheel cleaner instructions advise to take care to avoid contact with painted surfaces. Most
customers think of painted surfaces as the fenders, quarter panels and other exterior sheet metal.
Many vehicles have painted brake calipers. Acidic wheel cleaners may craze, crack, or discolor the
paint on the brake calipers. Damage from wheel cleaners is not covered under the vehicle new car
warranty. Soap and water applied with a soft brush is usually all that is required to clean the
calipers.
Whenever any wheel cleaner is used, it must be THOROUGHLY rinsed off of the wheel with clean,
clear water. Special care must be taken to rinse under the hub cap, balance weights, wheel nuts,
lug nut caps, between the wheel cladding and off the back side of the wheel. Wheels returned to
the Warranty Parts Center (WPC) that exhibit damage from wheel cleaners most often have the
damage around and under the wheel weight where the cleaner was incompletely flushed away.
Notice
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Technical Service Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 7886
Do not use cleaning solutions that contain hydrofluoric, oxalic and most other acids on chrome
wheels (or any wheels).
If the customer is unsure of the chemical make-up of a particular wheel cleaner, it should be
avoided.
For wheels showing signs of milky staining from acidic cleaners, refer to Customer Assistance and
Instructions below.
Warranty of Stained Chrome Wheels
Stained wheels are not warrantable. Most acid based cleaners will permanently stain chrome
wheels. Follow-up with dealers has confirmed that such cleaners were used on wheels that were
returned to the Warranty Parts Center (WPC). Any stained wheels received by the WPC will be
charged back to the dealership. To assist the customer, refer to Customer Assistance and
Instructions below.
Pitting or Spotted Appearance of Chrome Wheels Figure 2
A second type or staining or finish disturbance may result from road chemicals, such as calcium
chloride used for dust control of unpaved roads. The staining will look like small pitting (refer to
Figure 2). This staining will usually be on the leading edges of each wheel spoke, but may be
uniformly distributed. If a vehicle must be operated under such conditions, the chrome wheels
should be washed with mild soap and water and thoroughly rinsed as soon as conveniently
possible.
Important Road chemicals, such as calcium chloride used for dust control of unpaved roads, can
also stain chrome wheels. The staining will look like small pitting. This staining will usually be on
the leading edges of each wheel spoke. This is explained by the vehicle traveling in the forward
direction while being splashed by the road chemical. If a vehicle must be operated under such
conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed
as soon as conveniently possible.
Warranty of Pitted or Spotted Chrome Wheels
Wheels returned with pitting or spotting as a result of road chemicals may be replaced one time.
Damage resulting from contact with these applied road chemicals is corrosive to the wheels finish
and may cause damage if the wheels are not kept clean.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean if they are operating the vehicle in an area that
applies calcium chloride or other dust controlling chemicals! "GM of Canada" dealers require prior
approval by the District Manager - Customer Care and Service Process (DM-CCSP).
"Stardust" Corrosion of Chrome Wheels Figure 3
A third type of finish disturbance results from prolonged exposure to brake dust and resultant
penetration of brake dust through the chrome. As brakes are applied hot particles of brake material
are thrown off and tend to be forced through the leading edge of the wheel spoke windows by
airflow. These
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Technical Service Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 7887
hot particles embed themselves in the chrome layer and create a small pit. If the material is allowed
to sit on the wheel while it is exposed to moisture or salt, it will corrode the wheel beneath the
chrome leaving a pit or small blister in the chrome.
Heavy brake dust build-up should be removed from wheels by using GM Chrome Cleaner and
Polish, P/N 1050173 (in Canada use 10953013). For moderate cleaning, light brake dust build-up
or water spots use GM Swirl Remover Polish, P/N 12377965 (in Canada, use Meguiars
Plast-X(TM) Clear Plastic Cleaner and Polish #G12310C**). After cleaning, the wheel should be
waxed using GM Cleaner Wax, P/N 12377966 (in Canada, use Meguiars Cleaner Wax
#M0616C**), which will help protect the wheel from brake dust and reduce adhesion of any brake
dust that gets on the wheel surface. For general maintenance cleaning, PEEK Metal Polish† may
be used. It will clean and shine the chrome and leave behind a wax coating that may help protect
the finish.
Warranty of Stardust Corroded Chrome Wheels
Wheels returned with pitting or spotting as a result of neglect and brake dust build-up may be
replaced one time.
Important Notify the customer that this is a one time replacement. Please stress to the customer
the vital importance of keeping the wheels clean and free of prolonged exposure to brake dust
build-up. "GM of Canada" dealers require prior approval by the District Manager - Customer Care
and Service Process (DM-CCSP).
Customer Assistance and Instructions
GM has looked for ways customers may improve the appearance of wheels damaged by acidic
cleaners. The following product and procedure has been found to dramatically improve the
appearance of stained wheels. For wheels that have milky stains caused by acidic cleaners try the
following:
Notice
THE 3M CHROME AND METAL POLISH REQUIRED FOR THIS PROCEDURE IS AN
EXTREMELY AGGRESSIVE POLISH/CLEANER. THE WHEELS MUST BE CLEANED BEFORE
APPLICATION TO AVOID SCRATCHING THE WHEEL SURFACE. THIS PRODUCT WILL
REDUCE THE THICKNESS OF THE CHROME PLATING ON THE WHEEL AND IF USED
INCORRECTLY OR EXCESSIVELY MAY REMOVE THE CHROME PLATING ALL TOGETHER,
EXPOSING A LESS BRIGHT AND BRASSY COLORED SUB-LAYER. FOLLOW INSTRUCTIONS
EXACTLY.
1. Wash the wheels with vigorously with soap and water. This step will clean and may reduce
wheel staining. Flood all areas of the wheel with water
to rinse.
2. Dry the wheels completely.
Notice Begin with a small section of the wheel and with light pressure buff off polish and examine
results. ONLY apply and rub with sufficient force and time to remove enough staining that you are
satisfied with the results. Some wheels may be stained to the extent that you may only achieve a
50% improvement while others may be able to be restored to the original lustre. IN ALL CASES,
only apply until the results are satisfactory.
3. Apply 3M Chrome and Metal Polish #39527* with a clean terry cloth towel. As you apply the
polish, the staining will be diminished. 4. When dry, buff off the polish with a clean portion of the
towel. 5. Repeat application of the 3M Chrome and Metal Polish until satisfied with the results. If
continued applications fail to improve the appearance
further discontinue use.
This procedure will improve the appearance of the wheels and may, with repeated applications,
restore the finish dramatically. For wheels that exhibit spotting from road chemicals the above
procedure may marginally improve the condition but will not restore the finish or remove the pitting.
In this type of staining the wheel finish has actually been removed in spots and no manner of
cleaning will restore the finish.
†*We believe this source and their products to be reliable. There may be additional manufacturers
of such products/materials. General Motors does not endorse, indicate any preference for or
assume any responsibility for the products or material from this firm or for any such items that may
be available from other sources.
Parts Information
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Technical Service Bulletins > All Other Service Bulletins for Wheels: > 00-03-10-002F > Apr > 11 > Wheels - Chrome Wheel
Staining/Pitting/Corrosion > Page 7888
*This product is currently available from 3M. To obtain information for your local retail location
please call 3M at 1-888-364-3577.
**This product is currently available from Meguiars (Canada). To obtain information for your local
retail location please call Meguiars at 1-800-347-5700 or at www.meguiarscanada.com.
^ This product is currently available from Tri-Peek International. To obtain information for your local
retail location please call Tri-Peek at
1-877-615-4272 or at www.tripeek.com.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires Refinishing Aluminum Wheels
Wheels: All Technical Service Bulletins Wheels/Tires - Refinishing Aluminum Wheels
INFORMATION
Bulletin No.: 99-08-51-007E
Date: March 17, 2011
Subject: Refinishing Aluminum Wheels
Models:
2012 and Prior GM Passenger Cars and Trucks
Supercede: This bulletin is being revised to add additional model years. Please discard Corporate
Bulletin Number 99-08-51-007D (Section 08 - Body and Accessories).
This bulletin updates General Motor's position on refinishing aluminum wheels. GM does not
endorse any repairs that involve welding, bending, straightening or re-machining. Only cosmetic
refinishing of the wheel's coatings, using recommended procedures, is allowed.
Evaluating Damage
In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion,
scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be
sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the
wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been
refinished by an outside company must be returned to the same vehicle. The Dealer must record
the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to
Refinisher's Responsibility - Outside Company later in this bulletin.
Aluminum Wheel Refinishing Recommendations
- Chrome-plated aluminum wheels Re-plating these wheels is not recommended.
- Polished aluminum wheels These wheels have a polyester or acrylic clearcoat on them. If the
clearcoat is damaged, refinishing is possible. However, the required refinishing process cannot be
performed in the dealer environment. Refer to Refinisher's Responsibility - Outside Company later
in this bulletin.
- Painted aluminum wheels These wheels are painted using a primer, color coat, and clearcoat
procedure. If the paint is damaged, refinishing is possible. As with polished wheels, all original
coatings must be removed first. Media blasting is recommended. Refer to GM Aluminum
Refinishing Bulletin #53-17-03A for the re-painting of this type of wheel.
- Bright, machined aluminum wheels These wheels have a polyester or acrylic clearcoat on them.
In some cases, the recessed "pocket" areas of the wheel may be painted. Surface refinishing is
possible. The wheel must be totally stripped by media blasting or other suitable means. The wheel
should be resurfaced by using a sanding process rather than a machining process. This allows the
least amount of material to be removed.
Important Do not use any re-machining process that removes aluminum. This could affect the
dimensions and function of the wheel.
Painting is an option to re-clearcoating polished and bright machined aluminum wheels. Paint will
better mask any surface imperfections and is somewhat more durable than clearcoat alone. GM
recommends using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle
SILVER WA9967 for a very bright look. As an option, the body color may also be used. When using
any of the painting options, it is recommended that all four wheels be refinished in order to maintain
color uniformity. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for specific procedures
and product recommendations.
Refinisher's Responsibility - Outside Company
Important Some outside companies are offering wheel refinishing services. Such refinished wheels
will be permanently marked by the refinisher and are warranted by the refinisher. Any process that
re-machines or otherwise re-manufactures the wheel should not be used.
A refinisher's responsibility includes inspecting for cracks using the Zyglo system or the equivalent.
Any cracked wheels must not be refinished. No welding, hammering or reforming of any kind is
allowed. The wheel ID must be recorded and follow the wheel throughout the process in order to
assure that the same wheel is returned. A plastic media blast may be used for clean up of the
wheel. Hand and/or lathe sanding of the machined surface and the wheel window is allowed.
Material removal, though, must be kept to a minimum. Re-machining of the wheel is not allowed.
Paint and/or clear coat must not be present on the following surfaces: the nut chamfers, the wheel
mounting surfaces and the wheel pilot hole. The refinisher must permanently ID stamp the wheel
and warrant the painted/clearcoated surfaces for a minimum of one year or the remainder of the
new vehicle warranty, whichever is
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Technical Service Bulletins > All Other Service Bulletins for Wheels: > 99-08-51-007E > Mar > 11 > Wheels/Tires Refinishing Aluminum Wheels > Page 7893
longer.
Important Whenever a wheel is refinished, the mounting surface and the wheel nut contact
surfaces must not be painted or clearcoated. Coating these surfaces could affect the wheel nut
torque.
When re-mounting a tire on an aluminum wheel, coated balance weights must be used in order to
reduce the chance of future cosmetic damage.
Disclaimer
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Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions
Wheels: All Technical Service Bulletins Wheels - Changing Procedures/Precautions
INFORMATION
Bulletin No.: 06-03-10-010A
Date: June 09, 2010
Subject: Information on Proper Wheel Changing Procedures and Cautions
Models:
2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER Models 2005-2009 Saab
9-7X 2005-2009 Saturn Vehicles
Attention:
Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel
Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and
reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel
installation. Always refer to SI for wheel lug nut torque specifications and complete jacking
instructions for safe wheel changing.
Supercede: This bulletin is being revised to include the 2011 model year and update the available
special tool list. Please discard Corporate Bulletin Number 06-03-10-010 (Section 03 Suspension).
Frequency of Wheel Changes - Marketplace Driven
Just a few years ago, the increasing longevity of tires along with greater resistance to punctures
had greatly reduced the number of times wheels were removed to basically required tire rotation
intervals. Today with the booming business in accessory wheels/special application tires (such as
winter tires), consumers are having tire/wheel assemblies removed - replaced - or installed more
than ever. With this increased activity, it opens up more of a chance for error on the part of the
technician. This bulletin will review a few of the common concerns and mistakes to make yourself
aware of.
Proper Servicing Starts With the Right Tools
The following tools have been made available to assist in proper wheel and tire removal and
installation.
- J 41013 Rotor Resurfacing Kit (or equivalent)
- J 42450-A Wheel Hub Resurfacing Kit (or equivalent)
Corroded Surfaces
One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle.
Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened
wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed
away from water splash. This action may result in clearance at the mating surface of the wheel and
an under-torqued condition.
Caution
Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or
brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting
surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is
moving, possibly resulting in a loss of control or personal injury.
Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If
corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding
pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating
surface.
The J 41013 (or equivalent) can be used to clean the following surfaces:
- The hub mounting surface
- The brake rotor mounting surface
- The wheel mounting surface
Use the J 42450-A (or equivalent) to clean around the base of the studs and the hub.
Lubricants, Grease and Fluids
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Technical Service Bulletins > All Other Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 7898
Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in
removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to
installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper
readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY.
Notice
Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or
drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to
clean, dry wheel studs and surfaces ONLY. Beginning with 2011 model year vehicles, put a light
coating of grease, GM P/N 1051344 (in Canada, P/N 9930370), on the inner surface of the wheel
pilot hole to prevent wheel seizure to the axle or bearing hub.
Wheel Stud and Lug Nut Damage
Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse.
You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not
retain properly, yet give the impression of fully tightening. Always inspect and replace any
component suspected of damage.
Tip
Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged
BEFORE tightening the nut.
Important If the vehicle has directional tread tires, verify the directional arrow on the outboard side
of the tire is pointing in the direction of forward rotation.
Wheel Nut Tightening and Torque
Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid
additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown
for each vehicle in SI. Always observe the proper wheel nut tightening sequence as shown below in
order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off
center resulting in vibration.
The Most Important Service You Provide
While the above information is well known, and wheel removal so common, technicians run the risk
of becoming complacent on this very important
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 06-03-10-010A > Jun > 10 > Wheels - Changing
Procedures/Precautions > Page 7899
service operation. A simple distraction or time constraint that rushes the job may result in personal
injury if the greatest of care is not exercised. Make it a habit to double check your work and to
always side with caution when installing wheels.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 04-03-10-012B > Feb > 08 > Wheels - Chrome
Wheel Brake Dust Accumulation/Pitting
Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Brake Dust Accumulation/Pitting
Bulletin No.: 04-03-10-012B
Date: February 01, 2008
INFORMATION
Subject: Pitting and Brake Dust on Chrome wheels
Models: 2008 and Prior GM Passenger Cars and Trucks (including Saturn) 2008 and Prior
HUMMER H2, H3 2005-2008 Saab 9-7X
Supercede:
This bulletin is being revised to add model years. Please discard Corporate Bulletin Number
04-03-10-012A (Section 03 - Suspension).
Analysis of Returned Wheels
Chrome wheels returned under the New Vehicle Limited Warranty for pitting concerns have
recently been evaluated. This condition is usually most severe in the vent (or window) area of the
front wheels. This "pitting" may actually be brake dust that has been allowed to accumulate on the
wheel. The longer this accumulation builds up, the more difficult it is to remove.
Cleaning the Wheels
In all cases, the returned wheels could be cleaned to their original condition using GM Vehicle Care
Cleaner Wax, P/N 12377966 (in Canada, P/N 10952905). When using this product, you should
confine your treatment to the areas of the wheel that show evidence of the brake dust build-up.
This product is only for use on chromed steel or chromed aluminum wheels.
Parts Information
Warranty Information
Wheel replacement for this condition is NOT applicable under the terms of the New Vehicle Limited
Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 99-03-10-102 > Jun > 99 > Warranty - OE Chrome
Plated Aluminum Wheel ID
Wheels: All Technical Service Bulletins Warranty - OE Chrome Plated Aluminum Wheel ID
File In Section: 03 - Suspension
Bulletin No.: 99-03-10-102
Date: June, 1999
INFORMATION
Subject: Original Equipment Chrome Plated Aluminum Wheel Identification
Models: 1999 and Prior Passenger Cars and Light Duty Trucks
Chrome plated aluminum wheels have been returned to the Warranty Parts Center that are not the
original equipment (OE) components.
Original equipment chrome plated aluminum wheels can be identified by either a balance weight
clip retention groove (1) or a step (2) that is machined around both of the wheel's rim flanges. The
rim flanges (3) of painted original equipment aluminum wheels do not have a groove or a step.
Chrome plated aluminum wheels that do not have the wheel rim flange groove or step are
aftermarket chrome plated components and are NOT warrantable. Any aftermarket chrome wheels
received by the Warranty Parts Center will be charged back to the dealership.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 72-05-05 > Aug > 97 > Warranty - Guidelines for
Using E0420 Wheel Replace
Wheels: All Technical Service Bulletins Warranty - Guidelines for Using E0420 Wheel Replace
File In Section: Warranty Administration
Bulletin No.: 72-05-05
Date: August, 1997
WARRANTY ADMINISTRATION
Subject: Guidelines for Using EO42O Wheel Replace
Models: 1989-98 Passenger Cars and Light Duty Trucks
The purpose of this bulletin is to provide service personnel with guidelines for using the above
subject labor operation.
Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the
following:
^ Aluminum Wheels (including chrome plated) with Porosity - Wheels that exhibit porosity should
be repaired as described in the vehicle service manual. Wheels should not be replaced without
wholesale approval.
^ Aluminum Wheels (except chrome plated) with a "Finish Defect" - Wheels that exhibit a defect in
the finish, (i.e., discoloration or surface degradation) should be refinished as described in the
Corporate Service Bulletin Number 53-17-03A released in May, 1996.
^ Chrome Wheels - Wheels that are chromed and found to have a finish defect can only be
replaced.
^ Aluminum and chrome wheels replaced under warranty will be subject to random part review and
inspection. Those wheels inspected and found not to be defective and/or should have been
repaired, will be subject to charge back.
Wheels damaged by normal wear, road hazards, car wash brushes, or other physical or chemical
damage are not eligible for warranty coverage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing
Technical Service Bulletin # 531703A Date: 960501
Aluminum Wheels - Refinishing
File In Section: 10 - Body
Bulletin No.: 53-17-03A
Date: May, 1996
INFORMATION
Subject: Aluminum Wheel Refinishing
Models: 1991-96 Passenger Cars and Trucks
This bulletin is being revised to delete the 1990 model year and add the 1996 model year. Please
discard Corporate Bulletin Number 53-17-03 (Section 10 - Body).
This bulletin supersedes and cancels all previous service bulletins concerning the refinishing of
aluminum wheels. The purpose of this service bulletin is to assist dealerships in repairing the
discoloration or surface degradation that has occurred on styled aluminum wheels.
This bulletin provides NEW PROCEDURES AND SPECIFIC MATERIALS for the refinishing of
painted aluminum wheels or aluminum wheels with discoloration or surface degradation.
Important:
THE RE-MACHINING OF ALUMINUM WHEELS IS NOT RECOMMENDED. THE RE-CLEAR
COATING OF ALUMINUM WHEELS IS NO LONGER RECOMMENDED DUE TO CONCERNS OF
REPAIR DURABILITY
The new procedure requires the wheel surface be plastic media blasted to remove old paint or
clear coat. CHEMICAL STRIPPERS ARE NOT RECOMMENDED.
Material Required
System 1: DuPont Products
3939-S Cleaning Solvent 615/616 Etching Primer URO 5000 Primer Surfacer IMRON 6000
Basecoat 3440-S IMRON Clear
System 2: PPG Products
DX533 Aluminum Cleaner DX503 Aluminum Conditioner DP Epoxy Primer Deltron Basecoat
(DBC) Concept 2001 Clear Acrylic Urethane
System 3: Spies Hecker
Permahyd Silicone Remover 7090 Permahyd 1:1 Primer 4070 Permahyd 2:1 Surfacer 5080
Permahyd Base Coat Series 280/285 Permahyd H.S. Clearcoat 8060
Color Selection
If the wheels being painted were previously clearcoated aluminum, we would recommend using
Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a
very bright look. As an option to the customer, you may also use body color. For color
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing > Page 7916
selection and verification, refer to your paint manufacturer's color book. On wheels that were
previous clearcoated aluminum it is recommended that all four wheels and their center caps be
refinished to maintain color uniformity.
Important:
THE PRODUCTS LISTED MUST BE USED AS A SYSTEM. DO NOT MIX OTHER
MANUFACTURERS' PRODUCT LINES WITH THE REQUIRED MATERIALS. PRODUCTS
LISTED IN THIS BULLETIN HAVE SHOWN THE REQUIRED REPAIR DURABILITY, AND
CURRENTLY ARE THE ONLY PAINT SYSTEMS THAT MEET GM SPECIFICATION
4350M-A336.
Procedures
1. Remove wheels from vehicle. Tires may remain mounted on wheels.
2. Remove balance weights and mark their location on tire.
3. Wipe excess grease, etc. from wheels with wax and grease remover.
4. Have wheels plastic media blasted to remove clearcoat. FOR FURTHER INFORMATION ON
MEDIA BLASTING IN YOUR AREA, CALL US TECHNOLOGIES INC., CONTACT DAVE
ROSENBURG AT 1-800-634-9185.
Caution:
IT IS MANDATORY THAT ADEQUATE RESPIRATORY PROTECTION BE WORN. EXAMPLES
OF SUCH PROTECTION ARE: AIR LINE RESPIRATORS WITH FULL HOOD OR HALF MASK. IF
NOT AVAILABLE, USE A VAPOR/PARTICULATE RESPIRATOR THAT RESPIRATOR
MANUFACTURER RECOMMENDS AS EFFECTIVE FOR ISOCYANATE VAPOR AND MISTS
(UNLESS LOCAL REGULATIONS PREVAIL).
5. Painting Process
a. Refer to Attachments 1-3 for each System's individual formula and process.
b. After following the specific System's individual formula and process, follow these steps:
6. Unmask wheels.
7. Clean all wheel mounting surface of any corrosion, overspray, or dirt.
8. Install new coated balance weights, at marked locations.
9. Replace wheels on vehicle.
10. USE A TORQUE STICK ON AN IMPACT WRENCH, OR A TORQUE WRENCH TO
CONSISTENTLY AND UNIFORMLY FASTEN THE WHEEL TO THE SPECIFIED TORQUE FOR
THE VEHICLE. THE STAR PATTERN MUST BE FOLLOWED.
Important:
TORQUE STICKS MUST BE USED ANY TIME AN IMPACT WRENCH IS USED TO TIGHTEN
WHEEL NUTS.
Warranty Information
For vehicles repaired under warranty, use as shown.
Attachment 1 - DuPont Products
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing > Page 7917
Painting Process
System: Dupont Products
Paint Color Information: Corsican Silver WA EQ9283 Dupont # C9143, Sparkle Silver WA9967
Dupont # C9339
1. Wipe wheel with cleaning solvent: 3939-S, 3949-S or 3900-S.
2. Mask off tires.
Important:
3. Mask off all wheel mounting surfaces and wheel mount surfaces.
4. Apply two coats of 615/616-S etching primer to wheel allowing 10 minutes flash between coats.
Allow to dry for 30 minutes before applying primer coat.
5. Apply URO 5000 primer 1220/193-S + accelerator 389-S using two coats at 65-70 PSI at the
gun. Allow 12-15 minutes between coats. Force bake 30 minutes at 140°F (60°C).
6. Scuff sand using green Scotch-Brite pad.
7. Solvent wipe before top coating.
8. Apply IMRON 6000 base coat to wheel. 2-3 coats to hiding at 60-70 PSI allowing to flash
between coats. Base coat needs to dry 20-30 minutes before clearcoat is applied.
9. Apply 3440-S clearcoat to wheel using two coats at 60-70 PSI. Flash 10-15 minutes between
coats. 389-S can be used in basecoat and clearcoat to give faster set up times.
10. Allow overnight dry before reassemble. Can be baked for 30 minutes at 140°F (60°C).
Attachment 2 - PPG Products
Painting Process: PPG System
Paint Color Information: Corsican Silver WAEQ9283; PPG # DBC-3531, Sparkle Silver WA9967;
PPG # 35367
1. Wash entire wheel with aluminum cleaner DX533, mix 1:3 with water. Allow to react 2-3 minutes
and rinse thoroughly.
2. Wash entire wheel with aluminum conditioner DX5O3 straight from the container. Allow to react
2-3 minutes until pale gold or tan color develops. Rinse thoroughly and dry.
3. Mask off tires.
Important:
4. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
5. Apply 1-2 coats of DP Primer and allow to flash for 15-20 minutes.
6. Apply 2-3 coats of Deltron Basecoat (DBC) and allow to flash 20 minutes after the final coat.
7. Apply two (2) wet coats of Concept 2001 Acrylic urethane.
8. Flash 20 minutes and bake 140°F (60°C) for 30 minutes.
For more information contact your PPG Jobber.
Attachment 3 - Spies Hecker
Painting Process: Spies Hecker System
Paint Color Information: Corsican Silver AWEQ9283; SH-72913, Sparkle Silver WA9967;
SH-71912
1. Clean with Permahyd Silicone Remover 7090.
2. Mask off tires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheels > Component Information >
Technical Service Bulletins > All Other Service Bulletins for Wheels: > 531703A > May > 96 > Aluminum Wheels Refinishing > Page 7918
Important:
3. Mask off all wheel nut mounting surfaces and wheel mounting surfaces.
4. Apply 1-1/2 coats of Permahyd 1:1 Primer 4070. Mix 1:1 with Permahyd Hardener 3070 as per
TDS.
5. Allow to flash for 30 minutes.
6. Apply two (2) coats of Permahyd 2:1 Surfacer 5080. Mix 2:1 with Permahyd Hardener 3071 as
per TDS.
7. Bake for 60 minutes at 140°F (60°C) or allow to flash for 3 hours at 68°F (20°C).
8. Apply Permahyd Base Coat Series 280/285 as per TDS.
9. Allow to flash 10 to 15 minutes.
10. Apply 1 to 2 coats of Permacron High Solid Clear Coat 8060 as per TDS.
11. Allow to flash 10 minutes. Then bake at 140°F (60°C) for 40 minutes.
For more information, contact your SPIES HECKER Jobber.
We believe these sources and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Bearing > Component Information >
Adjustments
Wheel Bearing: Adjustments
FRONT WHEEL BEARINGS ADJUSTMENT
Fig. 2 Front Wheel Bearing Adjustment
1. While rotating wheel forward, torque spindle nut to 12 ft. lbs., Fig. 2. 2. Back off nut until just
loose then hand tighten nut and back it off again until either hole in spindle lines up with hole in nut.
Do not back off nut
more than 1/2 flat.
3. Install new cotter pin. With wheel bearing properly adjusted, there will be .001-.005 inch end
play.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Bearing > Component Information >
Adjustments > Page 7922
Wheel Bearing: Service and Repair
FRONT WHEEL BEARINGS
Fig. 3 Hub & Wheel Bearing Replacement
1. Raise car and remove front wheels. 2. On models equipped with anti-lock brake systems,
remove right and left wheel speed sensors as follows:
a. Under vehicle hood, disconnect speed sensor electrical harness. b. Raise and support vehicle,
then remove speed sensor harness bracket attaching bolt. c. Remove speed sensor to steering
knuckle attaching bolt, then remove speed sensor and bracket assembly and position aside. d.
Reverse procedure to install. Install wheel speed sensors by hand. Do not hammer sensors into
position, as damage may result.
3. On all models, remove bolts holding brake caliper to its mounting and insert a fabricated block
(11/16 x 1 1/16 x 2 inches in length) between
brake pads as caliper is being removed. Once removed, caliper can be wired or secured in some
manner away from disc.
4. Remove spindle nut and hub and disc assembly. Grease retainer and inner wheel bearing can
now be removed, Fig. 3. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Fastener > Component Information
> Technical Service Bulletins > Customer Interest for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels - Plastic Wheel
Nut Covers Loose/Missing
Wheel Fastener: Customer Interest Wheels - Plastic Wheel Nut Covers Loose/Missing
Bulletin No.: 01-03-10-009A
Date: July 27, 2004
TECHNICAL
Subject: Plastic Wheel Nut Covers Missing and/or Loose (Replace Missing Covers and Add
Sealant to All Covers)
Models: 2005 and All Prior Passenger Cars (Except All Cadillac Models and Pontiac GTO)
with Plastic Wheel Nut Covers
Supercede:
This bulletin is being revised to add additional models years. Please discard Corporate Bulletin
Number 01-03-10-009.
Condition
Some customers may comment that the plastic wheel nut covers are missing and/or loose.
Correction
Important:
^ DO NOT USE a silicone-based adhesive.
^ Do not apply the *permatex(R) around the threads in a circular pattern.
^ Apply a single bead across the threads approximately 10 mm (0.4 in) in length, 5 mm (0.2 in) in
height and 5 mm (0.2 in) in width.
Replace any missing plastic wheel nut covers with the appropriate covers and apply Permatex(R) #
2 Form A Gasket Sealant(R) to the threads of all the plastic wheel nut covers. Tighten finger tight
plus a 1/4 turn with a hand wrench.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products from this firm or for any other such items which may be available from other sources.
Permatex(R) # 2 Form A Gasket Sealant(R) part numbers (available at your local parts supplier)
^ P/N 80009 (2A/2AR) - 44 ml (1.5 oz) tube boxed
^ P/N 80015 (2AR) - 44 ml (1.5 oz) tube carded
^ P/N 80010 (2B/2BR) - 89 ml (3 oz) tube boxed
^ P/N 80016 (2BR) - 89 ml (3 oz) tube carded
^ P/N 80011 (2C) - 325 ml (11 oz) tube boxed
Warranty Information
For vehicles repaired under warranty, use the table.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Fastener > Component Information
> Technical Service Bulletins > Customer Interest for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels - Plastic Wheel
Nut Covers Loose/Missing > Page 7931
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Fastener > Component Information
> Technical Service Bulletins > All Technical Service Bulletins for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels Plastic Wheel Nut Covers Loose/Missing
Wheel Fastener: All Technical Service Bulletins Wheels - Plastic Wheel Nut Covers Loose/Missing
Bulletin No.: 01-03-10-009A
Date: July 27, 2004
TECHNICAL
Subject: Plastic Wheel Nut Covers Missing and/or Loose (Replace Missing Covers and Add
Sealant to All Covers)
Models: 2005 and All Prior Passenger Cars (Except All Cadillac Models and Pontiac GTO)
with Plastic Wheel Nut Covers
Supercede:
This bulletin is being revised to add additional models years. Please discard Corporate Bulletin
Number 01-03-10-009.
Condition
Some customers may comment that the plastic wheel nut covers are missing and/or loose.
Correction
Important:
^ DO NOT USE a silicone-based adhesive.
^ Do not apply the *permatex(R) around the threads in a circular pattern.
^ Apply a single bead across the threads approximately 10 mm (0.4 in) in length, 5 mm (0.2 in) in
height and 5 mm (0.2 in) in width.
Replace any missing plastic wheel nut covers with the appropriate covers and apply Permatex(R) #
2 Form A Gasket Sealant(R) to the threads of all the plastic wheel nut covers. Tighten finger tight
plus a 1/4 turn with a hand wrench.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products from this firm or for any other such items which may be available from other sources.
Permatex(R) # 2 Form A Gasket Sealant(R) part numbers (available at your local parts supplier)
^ P/N 80009 (2A/2AR) - 44 ml (1.5 oz) tube boxed
^ P/N 80015 (2AR) - 44 ml (1.5 oz) tube carded
^ P/N 80010 (2B/2BR) - 89 ml (3 oz) tube boxed
^ P/N 80016 (2BR) - 89 ml (3 oz) tube carded
^ P/N 80011 (2C) - 325 ml (11 oz) tube boxed
Warranty Information
For vehicles repaired under warranty, use the table.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Fastener > Component Information
> Technical Service Bulletins > All Technical Service Bulletins for Wheel Fastener: > 01-03-10-009A > Jul > 04 > Wheels Plastic Wheel Nut Covers Loose/Missing > Page 7937
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Steering and Suspension > Wheels and Tires > Wheel Fastener > Component Information
> Technical Service Bulletins > Page 7938
Wheel Fastener: Specifications
Wheel Nuts ..........................................................................................................................................
................................................ 140 Nm (100 ft lb)
CAUTION: If penetrating oil gets on the vertical surfaces between the wheel and the rotor or brake
drum. it could cause the wheel to work loose as the vehicle is driven, resulting in a loss of control
and an injury accident. Never use heat to loosen a tight wheel. It can shorten the life of the wheel,
bolts or spindle and bearings. Wheel nuts must be tightened in sequence and to the proper torque
to avoid bending the wheel or rotor.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Conditioning Switch > Component Information >
Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Air Mix Motor
Rear View Of Center Instrument Panel (With C67 Or C68)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Air Mix Motor > Page 7948
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Air Mix Motor > Page 7949
Rear View Of Center Instrument Panel (With C67 Or C68)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Air Mix Motor > Page 7950
Air Door Actuator / Motor: Locations Mode Valve Actuator
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Air Mix Motor > Page 7951
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Air Mix Motor > Page 7952
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Air Door, HVAC > Air Door Actuator / Motor, HVAC >
Component Information > Locations > Page 7953
Temperature Valve Actuator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Ambient Temperature Sensor / Switch HVAC > Component
Information > Locations > Inside Air Temperature Sensor
Ambient Temperature Sensor / Switch HVAC: Locations Inside Air Temperature Sensor
Instrument Panel Carrier, above Glove Box.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Ambient Temperature Sensor / Switch HVAC > Component
Information > Locations > Inside Air Temperature Sensor > Page 7958
Ambient Temperature Sensor / Switch HVAC: Locations Outside Air Temperature Sensor
Attached to Hood Latch Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates
Blower Motor: Customer Interest A/C - Odor at Start up in Humid Climates
File In Section: 1 - HVAC
Bulletin No.: 53-12-12A
Date: December, 1996
Subject: Air Conditioning Odor at Start Up in Humid Climates (Disinfect Evaporator Core, Install
Delayed Blower Control Package)
Models: 1993-96 Passenger Cars (Except GEO) 1993-96 Light Duty Models (Except Tracker)
This bulletin is being revised to update the wiring diagrams, add the Corvette (with RPO C60) and
delete medium/heavy duty trucks. Please discard Corporate Bulletin Number 53-12-12 (Section 1 HVAC).
Condition
Some owners may comment on odors emitted from the air conditioning system, primarily at start up
in hot, humid climates.
Cause
This odor may be the result of microbial growth on the evaporator core. When the blower motor fan
is turned on, the microbial growth may release an unpleasant musty odor into the passenger
compartment.
Correction
To remove odors of this type, it is necessary to eliminate the microbial growth and prevent its
recurrence. To accomplish this, these two procedures must be completed.
^ Deodorize the evaporator core using Deodorizing Aerosol Kit, P/N 12377951 (AC Delco 15-102).
^ Install the new A/C Delayed Blower Control Package, P/N 12370470, (AC Delco 15-8632).
The blower control package will enable the blower to run at high speed for five (5) minutes. It will
do so approximately fifty (50) minutes after the ignition has been turned off if the compressor had
been engaged for four (4) or more minutes prior to shutting off engine. By doing so, the evaporator
case and core are dried out, reducing the chances of a recurring A/C odor.
Procedure
1. Visually inspect the air conditioning evaporator drain hose for obstructions or working condition.
2. Apply deodorizing aerosol as described in the instructions supplied with the kit. Once the
deodorizer has been applied, some of the mixture may overflow from the drain hose.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7967
3. The chart identifies specific instructions for each vehicle. This chart will identify the proper
deodorizing procedure, template and wiring diagram. Deodorizing the evaporator case can easily
be done by removing the blower motor resistor and tape off opening. The nozzle can now be
inserted through a pierced hole in the tape to deodorize the evaporator case. For some of the
vehicles specified below, a drilling procedure is identified in the deodorizing instructions. This type
of alternative procedure and others can be done by using the referenced templates in the chart.
4. Complete detailed installation instructions are supplied with the blower control package.
Important:
A. 1996 ONLY (Use blower resistor location for drilling procedure)
B. 1994-1996 ONLY
Refer to appropriate Service Manual for enabling afterblow feature through on-board diagnostics.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7968
For vehicles repaired under warranty, use as shown.
Figure 1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7969
Figure 2
Figure 3
Figure 4
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7970
Figure 5
Figure 6
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7971
Figure 7
Figure 8
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7972
Figure 9
Figure 10
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7973
Figure 11
Figure 12
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7974
Figure 13
Figure 14
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7975
Figure 15
Figure 16
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7976
Figure 17
Figure 18
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7977
Figure 19
Figure 20
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7978
Figure 21
Figure 22
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7979
Figure 23
Figure 24
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7980
Figure 25
Figure 26
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Customer Interest for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid Climates > Page
7981
Figure 27
Figure 28
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates
Blower Motor: All Technical Service Bulletins A/C - Odor at Start up in Humid Climates
File In Section: 1 - HVAC
Bulletin No.: 53-12-12A
Date: December, 1996
Subject: Air Conditioning Odor at Start Up in Humid Climates (Disinfect Evaporator Core, Install
Delayed Blower Control Package)
Models: 1993-96 Passenger Cars (Except GEO) 1993-96 Light Duty Models (Except Tracker)
This bulletin is being revised to update the wiring diagrams, add the Corvette (with RPO C60) and
delete medium/heavy duty trucks. Please discard Corporate Bulletin Number 53-12-12 (Section 1 HVAC).
Condition
Some owners may comment on odors emitted from the air conditioning system, primarily at start up
in hot, humid climates.
Cause
This odor may be the result of microbial growth on the evaporator core. When the blower motor fan
is turned on, the microbial growth may release an unpleasant musty odor into the passenger
compartment.
Correction
To remove odors of this type, it is necessary to eliminate the microbial growth and prevent its
recurrence. To accomplish this, these two procedures must be completed.
^ Deodorize the evaporator core using Deodorizing Aerosol Kit, P/N 12377951 (AC Delco 15-102).
^ Install the new A/C Delayed Blower Control Package, P/N 12370470, (AC Delco 15-8632).
The blower control package will enable the blower to run at high speed for five (5) minutes. It will
do so approximately fifty (50) minutes after the ignition has been turned off if the compressor had
been engaged for four (4) or more minutes prior to shutting off engine. By doing so, the evaporator
case and core are dried out, reducing the chances of a recurring A/C odor.
Procedure
1. Visually inspect the air conditioning evaporator drain hose for obstructions or working condition.
2. Apply deodorizing aerosol as described in the instructions supplied with the kit. Once the
deodorizer has been applied, some of the mixture may overflow from the drain hose.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7987
3. The chart identifies specific instructions for each vehicle. This chart will identify the proper
deodorizing procedure, template and wiring diagram. Deodorizing the evaporator case can easily
be done by removing the blower motor resistor and tape off opening. The nozzle can now be
inserted through a pierced hole in the tape to deodorize the evaporator case. For some of the
vehicles specified below, a drilling procedure is identified in the deodorizing instructions. This type
of alternative procedure and others can be done by using the referenced templates in the chart.
4. Complete detailed installation instructions are supplied with the blower control package.
Important:
A. 1996 ONLY (Use blower resistor location for drilling procedure)
B. 1994-1996 ONLY
Refer to appropriate Service Manual for enabling afterblow feature through on-board diagnostics.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7988
For vehicles repaired under warranty, use as shown.
Figure 1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7989
Figure 2
Figure 3
Figure 4
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7990
Figure 5
Figure 6
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7991
Figure 7
Figure 8
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7992
Figure 9
Figure 10
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7993
Figure 11
Figure 12
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7994
Figure 13
Figure 14
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7995
Figure 15
Figure 16
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7996
Figure 17
Figure 18
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7997
Figure 19
Figure 20
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7998
Figure 21
Figure 22
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 7999
Figure 23
Figure 24
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8000
Figure 25
Figure 26
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > All Technical Service Bulletins for Blower Motor: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8001
Figure 27
Figure 28
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Page 8002
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor > Component Information > Technical Service
Bulletins > Page 8003
Blower Motor: Service and Repair
1. Disconnect battery ground cable. 2. Remove righthand instrument panel sound insulator
attaching screws, then pull panel rearward disengaging attaching studs. 3. Disconnect blower
assembly electrical connector. 4. Remove righthand hinge pillar trim finish panel. 5. Remove
secondary ECM bracket attaching screw, then position secondary ECM and bracket aside. 6.
Support blower motor assembly, then remove blower motor assembly attaching screws. 7. Remove
blower motor assembly. 8. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor Relay > Component Information > Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor Relay > Component Information > Locations >
Page 8007
LO Blower Relay, Rear Defog Relay And HI Blower Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor Resistor > Component Information >
Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor Resistor > Component Information >
Locations > Page 8011
Blower Resistor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor Switch > Component Information > Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Blower Motor Switch > Component Information > Locations
> Page 8015
Heater And A/C Blower Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Cabin Air Filter > Component Information > Locations
Cabin Air Filter: Locations
This vehicle does not contain a factory installed cabin air filter.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Specifications
Compressor Clutch: Specifications
Clutch Plate & Rotor Clearance
...............................................................................................................................................
0.50-0.76mm (0.020-0.030)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Specifications > Page 8023
Compressor Clutch: Locations
RH side of Engine, part of A/C Compressor
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly
Compressor Clutch: Service and Repair Clutch Plate and Hub Assembly
Remove or Disconnect
Clutch Plate And Hub Assembly Removal
1. Clamp the holding fixture J 33026 in a vise and attach compressor to holding fixture with thumb
screws J 33026-1.
2. With center screw forcing tip in place to thrust against the end of the shaft, thread the Clutch
Plate and Hub Assembly Installer-Remover J
33013-B into the hub. Hold the body of the remover with a wrench and turn the center screw into
the remover body to remove the clutch plate and hub assembly (Fig. 3).
NOTICE: Do not drive or pound on the clutch hub or shaft. Internal damage to compressor may
result. The forcing tip on J 33013-B remover-installer center screw must be flat or the end of the
shaft/axial plate assembly will be damaged.
3. Remove the shaft key and retain for reassembly.
Install or Connect
Shaft Key, Clutch Plate/Hub Installation
1. Install the shaft key into the hub key groove. Allow the key to project approximately 3.2mm (1/8")
out of the keyway. The shaft key is curved
slightly to provide an interference fit in the hub key groove.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8026
2. Be sure the frictional surface of the clutch plate and the clutch rotor are clean before installing
the clutch plate and hub assembly.
3. Align the shaft key with the shaft keyway and place the clutch plate and the hub assembly onto
the compressor shaft.
Installing Clutch Plate & Hub Assembly
4. Remove the forcing tip on J 33013-B clutch plate and hub assembly installer-remover center
screw and reverse the body direction on the center
screw, as shown in the illustration.
5. Install the clutch plate and hub installer-remover J 33013-B with bearing.
The body of the J 33013-B installer-remover should be backed off sufficiently to allow the center
screw to be threaded onto the end of the compressor shaft.
6. Hold the center screw with a wrench. Tighten the hex portion of the installer-remover J 33013-B
body to press the hub onto the shaft. Tighten the
body several turns, remove the installer and check to see that the shaft key is still in place in the
keyway before installing the clutch plate and hub assembly to its final position. The air gap between
frictional surfaces of the clutch plate and clutch rotor should be 0.50-0.76mm (0.020-0.030").
NOTICE: If the center screw is threaded fully onto the end of the compressor shaft. or if the body of
the installer is held and the center screw is rotated, the key will wedge and will break the clutch
hub.
7. Remove installer J 33013-B, check for proper positioning of the shaft key (even or slightly above
the clutch hub).
8. Spin the pulley rotor by hand to see that the rotor is not rubbing the clutch drive plate.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8027
Compressor Clutch: Service and Repair Clutch Rotor and/or Bearing
Remove or Disconnect
1. Remove the clutch plate and hub assembly as described previously.
Installing - Removing Pulley Rotor & Bearing Assembly Retaining Ring
2. Remove rotor and bearing assembly retaining ring, using snap ring pliers J 6083.
Installing Pulley Rotor/Bearing Puller Guide
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8028
Removing Pulley Rotor And Bearing Assembly
3. Install pulley rotor and bearing puller guide J 33023-A to the front head and install J 33020 pulley
rotor and bearing puller down into the inner
circle of slots in the rotor. Turn the J 33020 puller clockwise in the slots in the rotor.
4. Hold the J 33020 puller in place and tighten the puller screw against the puller guide to remove
the pulley rotor and bearing assembly. 5. To prevent damage to the pulley rotor during bearing
removal the rotor hub must be properly supported.
Pulley Rotor Bearing Removal
Remove the forcing screw from J 33020 puller and, with the puller tangs still engaged in the rotor
slots, invert the assembly onto a solid flat surface or blocks as shown in the illustration.
6. Drive the bearing out of the rotor hub with rotor bearing remover J 9398-A and J 29886 universal
handle.
NOTICE: It is not necessary to remove the staking in front of the bearing to remove the bearing,
however, it will be necessary to file away the old stake metal for proper clearance for the new
bearing to be installed into the rotor bore or the bearing may be damaged.
Install or Connect
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8029
Installing Pulley Rotor Bearing
1. lace the pulley rotor on the J 21352-A support block to fully support the rotor hub during bearing
installation.
NOTICE: DO NOT support the rotor by resting the pulley rim on a flat surface during the bearing
installation or the rotor face will be bent.
2. Align the new bearing squarely with the hub bore and using puller and bearing installer J 9481-A
with universal handle J 29886, drive the bearing
fully into the hub. The installer will apply force to the outer race of the bearing, if used as shown.
Staking Bearing In Rotor Hub Bore
3. Place bearing staking guide J 33019-1 and bearing staking pin J 33019-2 in the hub bore as
shown in the illustration. Shift the rotor and bearing
assembly on the J 21352-A support block to give full support of the hub under the staking pin
location. A heavy-duty rubber band may be used to hold the stake pin in the guide, and the stake
pin should be properly positioned in the guide after each impact on the pin.
4. Using care to prevent personal injury, strike the staking pin with a hammer until a metal stake,
similar to the original, is formed down to but not
touching the bearing.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8030
Bearing Staked In Place
Noisy bearing operation and reduced bearing life may result if outer bearing race is deformed while
staking, The stake metal should not contact the outer race of the bearing. Stake three places 120
degrees apart as shown in the illustration.
Installing Pulley Rotor And Bearing Assembly
5. With the compressor mounted to the J 33026 holding fixture, position the rotor and bearing
assembly on the front head. 6. Position the J 33017 pulley, rotor and bearing installer and J
33023-A puller pilot directly over the inner race of the bearing. 7. Position puller crossbar J 8433-1
on the puller pilot J 33023-A and assemble the two J 330262 through bolts and washers through
the puller bar
slots and thread them into the J 33026 holding fixture. The thread of the through bolts should
engage the full thickness of the holding fixture.
8. Tighten the center screw in the J 8433-1 puller crossbar to force the pulley rotor and bearing
assembly onto the compressor front head. Should the
J 33017 pulley rotor and bearing installer slip off direct in-line contact with the inner race of the
bearing, loosen the J 8433-1 center forcing screw and realign the installer and pilot so that the J
33017 installer will properly clear the front head.
9. Install rotor and bearing assembly retainer ring, using snap ring pliers J 6083.
10. Reinstall clutch plate and hub assembly as described previously.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8031
Compressor Clutch: Service and Repair Clutch Coil
Remove or Disconnect
1. Perform Steps through 4 of "Clutch Rotor and/or Bearings" removal procedure. Mark clutch coil
terminal location on compressor front head.
Clutch Coil Assembly Removal
2. Install J 33023-A puller pilot on front head of compressor. Also install J 8433-1 puller crossbar
with J 33025 puller legs as shown in the
illustration.
3. Tighten J 8433-3 forcing screw against the puller pilot to remove the clutch coil.
1. Place the clutch coil assembly on the front head with the terminals positioned at the "marked"
location.
2. Place the J 33024 clutch coil installer over the internal opening of the clutch coil housing and
align installer with the compressor front head.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8032
Installing Clutch Coil Assembly
3. Center the J 8433-1 puller crossbar in the counter- sunk center hole of the J 33024 clutch coil
installer. Install the J 3302-2 through bolts and
washers through the crossbar slots and thread them into the holding fixture J 33026 to full fixture
thickness.
4. Turn the center forcing screw of the J 8433-1 puller crossbar to force the clutch coil onto the
front head. Be sure clutch coil and J 33024 installer
stay "in-line" during installation.
Staking Clutch Coil To Front Head
5. When coil is fully seated on the front head, use a 1/8" diameter drift punch and stake the front
head at three places 120 degrees apart, to ensure
clutch coil remains in position.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch > Component
Information > Service and Repair > Clutch Plate and Hub Assembly > Page 8033
Details Of Stakes In Front Head For Clutch Coil
^ Stake size should be only one-half the area of the punch tip and be only approximately
0.28-0.35mm (0.010-0.015") deep.
6. Install rotor and bearing assembly and the clutch plate and hub assembly as described
previously.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Bearing >
Component Information > Service and Repair
Compressor Clutch Bearing: Service and Repair
Remove or Disconnect
1. Remove the clutch plate and hub assembly as described previously.
Installing - Removing Pulley Rotor & Bearing Assembly Retaining Ring
2. Remove rotor and bearing assembly retaining ring, using snap ring pliers J 6083.
Installing Pulley Rotor/Bearing Puller Guide
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Bearing >
Component Information > Service and Repair > Page 8037
Removing Pulley Rotor And Bearing Assembly
3. Install pulley rotor and bearing puller guide J 33023-A to the front head and install J 33020 pulley
rotor and bearing puller down into the inner
circle of slots in the rotor. Turn the J 33020 puller clockwise in the slots in the rotor.
4. Hold the J 33020 puller in place and tighten the puller screw against the puller guide to remove
the pulley rotor and bearing assembly. 5. To prevent damage to the pulley rotor during bearing
removal the rotor hub must be properly supported.
Pulley Rotor Bearing Removal
Remove the forcing screw from J 33020 puller and, with the puller tangs still engaged in the rotor
slots, invert the assembly onto a solid flat surface or blocks as shown in the illustration.
6. Drive the bearing out of the rotor hub with rotor bearing remover J 9398-A and J 29886 universal
handle.
NOTICE: It is not necessary to remove the staking in front of the bearing to remove the bearing,
however, it will be necessary to file away the old stake metal for proper clearance for the new
bearing to be installed into the rotor bore or the bearing may be damaged.
Install or Connect
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Bearing >
Component Information > Service and Repair > Page 8038
Installing Pulley Rotor Bearing
1. lace the pulley rotor on the J 21352-A support block to fully support the rotor hub during bearing
installation.
NOTICE: DO NOT support the rotor by resting the pulley rim on a flat surface during the bearing
installation or the rotor face will be bent.
2. Align the new bearing squarely with the hub bore and using puller and bearing installer J 9481-A
with universal handle J 29886, drive the bearing
fully into the hub. The installer will apply force to the outer race of the bearing, if used as shown.
Staking Bearing In Rotor Hub Bore
3. Place bearing staking guide J 33019-1 and bearing staking pin J 33019-2 in the hub bore as
shown in the illustration. Shift the rotor and bearing
assembly on the J 21352-A support block to give full support of the hub under the staking pin
location. A heavy-duty rubber band may be used to hold the stake pin in the guide, and the stake
pin should be properly positioned in the guide after each impact on the pin.
4. Using care to prevent personal injury, strike the staking pin with a hammer until a metal stake,
similar to the original, is formed down to but not
touching the bearing.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Bearing >
Component Information > Service and Repair > Page 8039
Bearing Staked In Place
Noisy bearing operation and reduced bearing life may result if outer bearing race is deformed while
staking, The stake metal should not contact the outer race of the bearing. Stake three places 120
degrees apart as shown in the illustration.
Installing Pulley Rotor And Bearing Assembly
5. With the compressor mounted to the J 33026 holding fixture, position the rotor and bearing
assembly on the front head. 6. Position the J 33017 pulley, rotor and bearing installer and J
33023-A puller pilot directly over the inner race of the bearing. 7. Position puller crossbar J 8433-1
on the puller pilot J 33023-A and assemble the two J 330262 through bolts and washers through
the puller bar
slots and thread them into the J 33026 holding fixture. The thread of the through bolts should
engage the full thickness of the holding fixture.
8. Tighten the center screw in the J 8433-1 puller crossbar to force the pulley rotor and bearing
assembly onto the compressor front head. Should the
J 33017 pulley rotor and bearing installer slip off direct in-line contact with the inner race of the
bearing, loosen the J 8433-1 center forcing screw and realign the installer and pilot so that the J
33017 installer will properly clear the front head.
9. Install rotor and bearing assembly retainer ring, using snap ring pliers J 6083.
10. Reinstall clutch plate and hub assembly as described previously.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Coil > Component
Information > Service and Repair
Compressor Clutch Coil: Service and Repair
Remove or Disconnect
1. Perform Steps through 4 of "Clutch Rotor and/or Bearings" removal procedure. Mark clutch coil
terminal location on compressor front head.
Clutch Coil Assembly Removal
2. Install J 33023-A puller pilot on front head of compressor. Also install J 8433-1 puller crossbar
with J 33025 puller legs as shown in the
illustration.
3. Tighten J 8433-3 forcing screw against the puller pilot to remove the clutch coil.
1. Place the clutch coil assembly on the front head with the terminals positioned at the "marked"
location.
2. Place the J 33024 clutch coil installer over the internal opening of the clutch coil housing and
align installer with the compressor front head.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Coil > Component
Information > Service and Repair > Page 8043
Installing Clutch Coil Assembly
3. Center the J 8433-1 puller crossbar in the counter- sunk center hole of the J 33024 clutch coil
installer. Install the J 3302-2 through bolts and
washers through the crossbar slots and thread them into the holding fixture J 33026 to full fixture
thickness.
4. Turn the center forcing screw of the J 8433-1 puller crossbar to force the clutch coil onto the
front head. Be sure clutch coil and J 33024 installer
stay "in-line" during installation.
Staking Clutch Coil To Front Head
5. When coil is fully seated on the front head, use a 1/8" diameter drift punch and stake the front
head at three places 120 degrees apart, to ensure
clutch coil remains in position.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Coil > Component
Information > Service and Repair > Page 8044
Details Of Stakes In Front Head For Clutch Coil
^ Stake size should be only one-half the area of the punch tip and be only approximately
0.28-0.35mm (0.010-0.015") deep.
6. Install rotor and bearing assembly and the clutch plate and hub assembly as described
previously.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Hub > Component
Information > Specifications
Compressor Clutch Hub: Specifications
Clutch Plate & Rotor Clearance
...............................................................................................................................................
0.50-0.76mm (0.020-0.030)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Hub > Component
Information > Specifications > Page 8048
Compressor Clutch Hub: Service and Repair
Remove or Disconnect
Clutch Plate And Hub Assembly Removal
1. Clamp the holding fixture J 33026 in a vise and attach compressor to holding fixture with thumb
screws J 33026-1.
2. With center screw forcing tip in place to thrust against the end of the shaft, thread the Clutch
Plate and Hub Assembly Installer-Remover J
33013-B into the hub. Hold the body of the remover with a wrench and turn the center screw into
the remover body to remove the clutch plate and hub assembly (Fig. 3).
NOTICE: Do not drive or pound on the clutch hub or shaft. Internal damage to compressor may
result. The forcing tip on J 33013-B remover-installer center screw must be flat or the end of the
shaft/axial plate assembly will be damaged.
3. Remove the shaft key and retain for reassembly.
Install or Connect
Shaft Key, Clutch Plate/Hub Installation
1. Install the shaft key into the hub key groove. Allow the key to project approximately 3.2mm (1/8")
out of the keyway. The shaft key is curved
slightly to provide an interference fit in the hub key groove.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Clutch Hub > Component
Information > Specifications > Page 8049
2. Be sure the frictional surface of the clutch plate and the clutch rotor are clean before installing
the clutch plate and hub assembly.
3. Align the shaft key with the shaft keyway and place the clutch plate and the hub assembly onto
the compressor shaft.
Installing Clutch Plate & Hub Assembly
4. Remove the forcing tip on J 33013-B clutch plate and hub assembly installer-remover center
screw and reverse the body direction on the center
screw, as shown in the illustration.
5. Install the clutch plate and hub installer-remover J 33013-B with bearing.
The body of the J 33013-B installer-remover should be backed off sufficiently to allow the center
screw to be threaded onto the end of the compressor shaft.
6. Hold the center screw with a wrench. Tighten the hex portion of the installer-remover J 33013-B
body to press the hub onto the shaft. Tighten the
body several turns, remove the installer and check to see that the shaft key is still in place in the
keyway before installing the clutch plate and hub assembly to its final position. The air gap between
frictional surfaces of the clutch plate and clutch rotor should be 0.50-0.76mm (0.020-0.030").
NOTICE: If the center screw is threaded fully onto the end of the compressor shaft. or if the body of
the installer is held and the center screw is rotated, the key will wedge and will break the clutch
hub.
7. Remove installer J 33013-B, check for proper positioning of the shaft key (even or slightly above
the clutch hub).
8. Spin the pulley rotor by hand to see that the rotor is not rubbing the clutch drive plate.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Shaft Seal > Component
Information > Technical Service Bulletins > A/C Compressor Seal Washer - Reference Chart
Compressor Shaft Seal: Technical Service Bulletins A/C Compressor Seal Washer - Reference
Chart
File In Section: 1 - HVAC
Bulletin No.: 63-12-15
Date: November, 1996
INFORMATION
Subject: Reference Chart for A/C Compressor Seal Washers
Models: 1997 and Prior Passenger Cars (Except Corvette and GEO) 1997 and Prior Light Duty
Trucks (Except Tracker)
GMSPO A/C compressors include a seal washer kit. These kits contain various color edge painted
washer seals and inserts in which only two (2) washers and possibly one (1) insert are used. It has
come to our attention that some packaging discrepancies were found and some of the seals cannot
be properly identified for installation.
These seals are very close in size and some of the seals were inadvertently edge painted the
wrong color or not painted.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Shaft Seal > Component
Information > Technical Service Bulletins > A/C Compressor Seal Washer - Reference Chart > Page 8054
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Shaft Seal > Component
Information > Technical Service Bulletins > A/C Compressor Seal Washer - Reference Chart > Page 8055
The chart shown will help to properly identify the seals. Use the chart by placing the seal over the
pictured seal to identity inside and outside diameters and thickness. Because these seals are very
similar in size, specifications are also listed in the chart.
Important:
If seals are damaged upon installation, obtain new seal kit. Seals will be available separately at a
later date.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Shaft Seal > Component
Information > Technical Service Bulletins > Page 8056
Compressor Shaft Seal: Service and Repair
Seal Leak Detection
A shaft seal should not be changed because of small amounts of oil found on an adjacent surface
but only after actual refrigerant leakage is found using an approved leak detector, J 39400 or
equivalent.
Remove or Disconnect
1. Recover the refrigerant using J 39500-GM.
2. Loosen and reposition compressor in mounting brackets, if necessary.
3. Remove clutch plate and hub assembly from compressor as described in minor repairs.
Removing Or Installing Shaft Seal Retaining Ring
4. Remove the shaft seal retainer ring, using snap ring pliers J 5403.
5. Thoroughly clean inside of compressor neck area surrounding the shaft, the exposed portion of
the seal, the retainer ring groove and the shaft
itself. Any dirt or foreign material getting into compressor may cause damage.
Removing Or Installing Shaft Seal
6. Fully engage the knurled tangs of Seal Remover-Installer J 23128-A into the recessed portion of
the Seal by turning the handle clockwise. Remove
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Shaft Seal > Component
Information > Technical Service Bulletins > Page 8057
the Seal from the compressor with a rotary-pulling motion. Discard the seal. The handle must be
hand- tightened securely. Do not use a wrench or pliers.
Removing And Installing Shaft Seal And O-Ring
7. Remove and discard the seal seat O-ring from the compressor neck using O-ring remover J
955301, illustration.
8. Recheck the shaft and inside of the compressor neck for dirt or foreign material and be sure
these areas are perfectly clean before installing new
parts.
Clean ^
Thoroughly clean O-ring seal groove in front head.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor HVAC > Compressor Shaft Seal > Component
Information > Technical Service Bulletins > Page 8058
Compressor Shaft Seal
NOTICE: Seals should not be re-used. Always use a new specification service seal on rebuild. Be
sure that the seal to be installed is not scratched or damaged in anyway. Make sure that the seal
seat and seal are free of lint and dirt that could damage the seal surface or prevent sealing.
Install or Connect
1. Dip the new seal seat O-ring in clean 525 viscosity refrigerant oil and assemble onto O-ring
installer J 33011.
2. Insert the O-ring installer J 33011 into the compressor neck until the installer "bottoms". Lower
the moveable slide of the O-ring installer to
release the O-ring into the seal O-ring lower groove. (The compressor neck top groove is for the
shaft seal retainer ring.) Rotate the installer to seat the O-ring and remove the installer.
3. Dip the new seal in clean 525 viscosity refrigerant oil and assemble seal to Seal Installer J
23128-A, by turning handle clockwise. The stamped
steel case side of the lip seal must be engaged with knurled tangs of installer so that flared-out side
of lip seal is facing and installed towards the compressor. Install seal protector J 34614, in the seal
lip and place over the compressor shaft, and push the seal in place with a rotary motion or place
the seal protector J 34014 over end of compressor shaft, and slide the new seal onto the shaft with
a rotary motion until it stops. Take care not to dislodge the O-ring. Be sure the seal makes good
contact with the O-ring. Disengage the installer from the seal and remove the installer J 23128-A
and the seal protector J 34614.
NOTICE: Handling and care of seal protector is important. If seal protector is nicked or the bottom
flared, the new seal may be damaged during installation.
4. Install the new seal retainer ring with its flat side against the Seal, using Snap-Ring Pliers J
5403. Use the sleeve from O-ring installer J 33011 to
press in on the seal retainer ring so that it snaps into its groove.
5. To leak test, install compressor leak test fixture J 39893 on rear head of compressor and
connect gage charging lines and J 39500-GM Refrigerant
Recovery System. Pressurize suction and high-side of compressor with R-134a Refrigerant.
Temporarily install (M9 x 1.25 thread on shaft) nut and, with the compressor in horizontal position,
rotate the compressor shaft in normal direction of rotation several turns by hand. Leak test the seal
area and correct and leak found. Recover the refrigerant. Remove shaft nut.
6. Remove any excess oil resulting from installing the new seal parts from the shaft and inside the
compressor neck.
7. Install the clutch plate and hub assembly as described in minor repair procedures.
8. Reinstall compressor belt and tighten bracket.
9. Evacuate and charge the refrigerant system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor Clutch Diode HVAC > Component Information
> Locations
Compressor Clutch Diode HVAC: Locations
Engine Harness, near A/C Compressor Clutch Connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Compressor Clutch Relay > Component Information >
Locations
Compressor Clutch Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Control Assembly, HVAC > Component Information >
Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Control Assembly, HVAC > Component Information >
Diagrams > Electronic A/C Power Module & Heater A/C Programmer
Electronic A/C Power Module And Heater A/C Programmer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Control Assembly, HVAC > Component Information >
Diagrams > Electronic A/C Power Module & Heater A/C Programmer > Page 8070
Control Assembly: Diagrams Heater and A/C Control
Heater And A/C Control (C67) (C1)
C201, C302, C303, C351, C400, C401 & C406: Heater & A/C Control (C67) (C2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 99-01-39-004C > Jun > 09 > A/C - Musty Odors Emitted From
(HVAC) System
Evaporator Core: Customer Interest A/C - Musty Odors Emitted From (HVAC) System
TECHNICAL
Bulletin No.: 99-01-39-004C
Date: June 12, 2009
Subject: Air Conditioning Odor (Install Evaporator Core Dryer Kit and Apply Cooling Coil Coating)
Models:
1993-2010 GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 All
Equipped with Air Conditioning
Supercede: This bulletin is being revised to add the 2009 and 2010 model years. Please discard
Corporate Bulletin Number 99-01-39-004B (Section 01 - HVAC).
Condition
Some customers may comment about musty odors emitted from the Heating, Ventilation and Air
Conditioning (HVAC) system at vehicle start-up in hot, humid conditions.
Cause
This condition may be caused by condensate build-up on the evaporator core, which does not
evaporate by itself in high humidity conditions. The odor may be the result of microbial growth on
the evaporator core. When the blower motor fan is turned on, the microbial growth may release an
unpleasant musty odor into the passenger compartment.
There are several other possible sources of a musty odor in a vehicle. A common source is a water
leak into the interior of the vehicle or foreign material in the HVAC air distribution system. Follow
the procedures in SI for identifying and correcting water leaks and air inlet inspection.
The procedure contained in this bulletin is only applicable if the odor source has been determined
to be microbial growth on the evaporator core inside the HVAC module.
Correction
Many vehicles currently incorporate an afterblow function within the HVAC control module
software. The afterblow feature, when enabled, employs the HVAC blower fan to dry the
evaporator after vehicle shut down and this function will inhibit microbial growth. Technicians are to
confirm that the customer concern is evaporator core odor and that the vehicle has the imbedded
afterblow feature, as defined in the SI document for that specific vehicle model, model year and
specific HVAC option. Refer to SI for enabling the afterblow function. Vehicles being delivered in
areas prone to high humidity conditions may benefit from having the afterblow enabled calibration
installed prior to any customer comment.
Important If the vehicle is not factory equipped with the imbedded afterblow enable feature, it may
be added with the Electronic Evaporator Dryer Module Kit (P/N 12497910 or AC Delco 15-5876).
Important When installing the Electronic Evaporator Dryer Module, you MUST use the included
electrical splice connectors to ensure a proper splice. Complete detailed installation instructions
and self testing procedures are supplied with the kit. If necessary, the Electronic Evaporator Dryer
Module may be installed underhood if it is protected from extreme heat and water splash areas.
To immediately remove the evaporator core odor on all suspect vehicles, it is necessary to
eliminate the microbial growth and prevent its re-occurrence. To accomplish this, perform the
following procedure:
Vehicle and Applicator Tool Preparation
1. The evaporator core must be dry. This may be accomplished by disabling the compressor and
running the blower fan on the recirc heat setting for
an extended period of time.
Note Compressor engagement will cause the evaporator core to remain wet and will prevent full
adherence of the Coiling Coil Coating to the evaporator core surfaces.
2. Verify that the air conditioning drain hose is not clogged and place a drain pan beneath the
vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 99-01-39-004C > Jun > 09 > A/C - Musty Odors Emitted From
(HVAC) System > Page 8079
3. Place a protective cover over the carpet below the evaporator core. 4. Remove the cabin air
filter, if equipped, and cover the opening prior to applying the Cooling Coil Coating, as the product
may clog the filter. If the
cabin air filter appears to have little or no remaining life, suggest a replacement to your customer.
5. If the HVAC module has a blower motor cooling tube, be careful NOT TO SPRAY THE
COOLING COIL COATING INTO THE
BLOWER MOTOR COOLING TUBE.
6. Attach the Flexible Applicator Pressure Spray Tool (J-43810-20A) to a compressed air line
operating at 586 kPa (85 psi) to 793 kPa (115 psi). 7. Shake the bottle of Cooling Coil Coating well.
Screw the bottle onto the cap on the applicator tool's pick-up tube.
Note The pick-up tube is designed for 120 ml (4 oz) and 240 ml (8 oz) bottles and should coil
slightly in the bottom of a 120 ml (4 oz) bottle.
8. Use one of the following three methods to apply the Cooling Coil Coating.
Important If the Pressure Applicator Spray Tool (J-43810-20A) is not available, the Cooling Coil
Coating is also available in an aerosol can (P/N 12377951 (in Canada, 10953503)).
Application Through Blower Motor Control Module Opening
- Remove the blower motor control module (blower motor resistor). Refer to the applicable
procedure in SI.
- Clean any debris or foreign material from inside the HVAC module and on the evaporator core
surface.
- Apply the Cooling Coil Coating directly to the evaporator core through the blower motor blower
motor control module (blower motor resistor) opening.
- Use the flexible wand to direct the Cooling Coil Coating over the entire evaporator core and
surrounding gasket surfaces.
- When the application is complete, install the blower motor blower motor control module (blower
motor control module).
Application Through Blower Motor Opening
- Remove the blower motor. Refer to the applicable blower motor removal procedure in SI.
- Clean any debris or foreign material from inside the HVAC module and on the evaporator core
surface.
- Apply the Cooling Coil Coating directly to the evaporator core through the blower motor opening.
- Use the flexible wand to direct the Cooling Coil Coating over the entire evaporator core and
surrounding gasket surfaces.
- When the application is complete, install the blower motor.
Application Through a Hole in the HVAC Module
- If neither of the two previous application methods are available, it may be necessary to drill a hole
in the HVAC module.
- Locate an area of the HVAC module between the blower motor and the evaporator core. Drill a 10
mm (3/8 in) hole in the HVAC module. Use caution to keep the drill clear of the evaporator core and
the blower motor fan.
- With the air distribution vents closed and the blower motor fan speed on HIGH, insert the
applicator tool into the hole and spray the Cooling Coil Coating into the airstream toward the
evaporator core.
- Use a GM approved RTV sealant to plug the hole in the HVAC module.
9. After the Cooling Coil Coating application is complete, start and run the vehicle for approximately
10 minutes, with the compressor disabled,
HVAC mode set to Recirculate/Max, heat set to full warm, blower motor fan speed on high, and
one window open approximately 12 mm (1/2 in). This cures the Cooling Coil Coating onto the
evaporator core surface.
10. While the engine is running, rinse the applicator tool with warm water to prolong the life of the
tool. Be sure to spray warm water through the
nozzle to rinse out any residual Cooling Coil Coating still in the capillary pick up tube, otherwise it
will dry and clog the applicator tool. Also remove the small green valve from the bottle cap and
rinse it thoroughly while rolling it between two fingers and then reinstall it. If this valve is clogged ,
the Cooling Coil Coating will not flow through the applicator tool.
11. Shut off the engine and enable the compressor again. 12. Verify proper HVAC system
operation. 13. Remove the protective cover from inside the vehicle. 14. Remove the drain pan from
underneath the vehicle. 15. Reinstall the cabin air filter if necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 99-01-39-004C > Jun > 09 > A/C - Musty Odors Emitted From
(HVAC) System > Page 8080
Parts Information
Important The Cooling Coil Coating listed below is the only GM approved product for use under
warranty as an evaporator core disinfectant and for the long term control of evaporator core
microbial growth.
Warranty Information
For vehicles repaired under warranty, use the table above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates
Evaporator Core: Customer Interest A/C - Odor at Start up in Humid Climates
File In Section: 1 - HVAC
Bulletin No.: 53-12-12A
Date: December, 1996
Subject: Air Conditioning Odor at Start Up in Humid Climates (Disinfect Evaporator Core, Install
Delayed Blower Control Package)
Models: 1993-96 Passenger Cars (Except GEO) 1993-96 Light Duty Models (Except Tracker)
This bulletin is being revised to update the wiring diagrams, add the Corvette (with RPO C60) and
delete medium/heavy duty trucks. Please discard Corporate Bulletin Number 53-12-12 (Section 1 HVAC).
Condition
Some owners may comment on odors emitted from the air conditioning system, primarily at start up
in hot, humid climates.
Cause
This odor may be the result of microbial growth on the evaporator core. When the blower motor fan
is turned on, the microbial growth may release an unpleasant musty odor into the passenger
compartment.
Correction
To remove odors of this type, it is necessary to eliminate the microbial growth and prevent its
recurrence. To accomplish this, these two procedures must be completed.
^ Deodorize the evaporator core using Deodorizing Aerosol Kit, P/N 12377951 (AC Delco 15-102).
^ Install the new A/C Delayed Blower Control Package, P/N 12370470, (AC Delco 15-8632).
The blower control package will enable the blower to run at high speed for five (5) minutes. It will
do so approximately fifty (50) minutes after the ignition has been turned off if the compressor had
been engaged for four (4) or more minutes prior to shutting off engine. By doing so, the evaporator
case and core are dried out, reducing the chances of a recurring A/C odor.
Procedure
1. Visually inspect the air conditioning evaporator drain hose for obstructions or working condition.
2. Apply deodorizing aerosol as described in the instructions supplied with the kit. Once the
deodorizer has been applied, some of the mixture may overflow from the drain hose.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8085
3. The chart identifies specific instructions for each vehicle. This chart will identify the proper
deodorizing procedure, template and wiring diagram. Deodorizing the evaporator case can easily
be done by removing the blower motor resistor and tape off opening. The nozzle can now be
inserted through a pierced hole in the tape to deodorize the evaporator case. For some of the
vehicles specified below, a drilling procedure is identified in the deodorizing instructions. This type
of alternative procedure and others can be done by using the referenced templates in the chart.
4. Complete detailed installation instructions are supplied with the blower control package.
Important:
A. 1996 ONLY (Use blower resistor location for drilling procedure)
B. 1994-1996 ONLY
Refer to appropriate Service Manual for enabling afterblow feature through on-board diagnostics.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8086
For vehicles repaired under warranty, use as shown.
Figure 1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8087
Figure 2
Figure 3
Figure 4
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8088
Figure 5
Figure 6
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8089
Figure 7
Figure 8
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8090
Figure 9
Figure 10
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8091
Figure 11
Figure 12
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8092
Figure 13
Figure 14
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8093
Figure 15
Figure 16
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8094
Figure 17
Figure 18
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8095
Figure 19
Figure 20
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8096
Figure 21
Figure 22
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8097
Figure 23
Figure 24
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8098
Figure 25
Figure 26
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Customer Interest for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in Humid
Climates > Page 8099
Figure 27
Figure 28
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 99-01-39-004C > Jun > 09 > A/C - Musty Odors
Emitted From (HVAC) System
Evaporator Core: All Technical Service Bulletins A/C - Musty Odors Emitted From (HVAC) System
TECHNICAL
Bulletin No.: 99-01-39-004C
Date: June 12, 2009
Subject: Air Conditioning Odor (Install Evaporator Core Dryer Kit and Apply Cooling Coil Coating)
Models:
1993-2010 GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 All
Equipped with Air Conditioning
Supercede: This bulletin is being revised to add the 2009 and 2010 model years. Please discard
Corporate Bulletin Number 99-01-39-004B (Section 01 - HVAC).
Condition
Some customers may comment about musty odors emitted from the Heating, Ventilation and Air
Conditioning (HVAC) system at vehicle start-up in hot, humid conditions.
Cause
This condition may be caused by condensate build-up on the evaporator core, which does not
evaporate by itself in high humidity conditions. The odor may be the result of microbial growth on
the evaporator core. When the blower motor fan is turned on, the microbial growth may release an
unpleasant musty odor into the passenger compartment.
There are several other possible sources of a musty odor in a vehicle. A common source is a water
leak into the interior of the vehicle or foreign material in the HVAC air distribution system. Follow
the procedures in SI for identifying and correcting water leaks and air inlet inspection.
The procedure contained in this bulletin is only applicable if the odor source has been determined
to be microbial growth on the evaporator core inside the HVAC module.
Correction
Many vehicles currently incorporate an afterblow function within the HVAC control module
software. The afterblow feature, when enabled, employs the HVAC blower fan to dry the
evaporator after vehicle shut down and this function will inhibit microbial growth. Technicians are to
confirm that the customer concern is evaporator core odor and that the vehicle has the imbedded
afterblow feature, as defined in the SI document for that specific vehicle model, model year and
specific HVAC option. Refer to SI for enabling the afterblow function. Vehicles being delivered in
areas prone to high humidity conditions may benefit from having the afterblow enabled calibration
installed prior to any customer comment.
Important If the vehicle is not factory equipped with the imbedded afterblow enable feature, it may
be added with the Electronic Evaporator Dryer Module Kit (P/N 12497910 or AC Delco 15-5876).
Important When installing the Electronic Evaporator Dryer Module, you MUST use the included
electrical splice connectors to ensure a proper splice. Complete detailed installation instructions
and self testing procedures are supplied with the kit. If necessary, the Electronic Evaporator Dryer
Module may be installed underhood if it is protected from extreme heat and water splash areas.
To immediately remove the evaporator core odor on all suspect vehicles, it is necessary to
eliminate the microbial growth and prevent its re-occurrence. To accomplish this, perform the
following procedure:
Vehicle and Applicator Tool Preparation
1. The evaporator core must be dry. This may be accomplished by disabling the compressor and
running the blower fan on the recirc heat setting for
an extended period of time.
Note Compressor engagement will cause the evaporator core to remain wet and will prevent full
adherence of the Coiling Coil Coating to the evaporator core surfaces.
2. Verify that the air conditioning drain hose is not clogged and place a drain pan beneath the
vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 99-01-39-004C > Jun > 09 > A/C - Musty Odors
Emitted From (HVAC) System > Page 8105
3. Place a protective cover over the carpet below the evaporator core. 4. Remove the cabin air
filter, if equipped, and cover the opening prior to applying the Cooling Coil Coating, as the product
may clog the filter. If the
cabin air filter appears to have little or no remaining life, suggest a replacement to your customer.
5. If the HVAC module has a blower motor cooling tube, be careful NOT TO SPRAY THE
COOLING COIL COATING INTO THE
BLOWER MOTOR COOLING TUBE.
6. Attach the Flexible Applicator Pressure Spray Tool (J-43810-20A) to a compressed air line
operating at 586 kPa (85 psi) to 793 kPa (115 psi). 7. Shake the bottle of Cooling Coil Coating well.
Screw the bottle onto the cap on the applicator tool's pick-up tube.
Note The pick-up tube is designed for 120 ml (4 oz) and 240 ml (8 oz) bottles and should coil
slightly in the bottom of a 120 ml (4 oz) bottle.
8. Use one of the following three methods to apply the Cooling Coil Coating.
Important If the Pressure Applicator Spray Tool (J-43810-20A) is not available, the Cooling Coil
Coating is also available in an aerosol can (P/N 12377951 (in Canada, 10953503)).
Application Through Blower Motor Control Module Opening
- Remove the blower motor control module (blower motor resistor). Refer to the applicable
procedure in SI.
- Clean any debris or foreign material from inside the HVAC module and on the evaporator core
surface.
- Apply the Cooling Coil Coating directly to the evaporator core through the blower motor blower
motor control module (blower motor resistor) opening.
- Use the flexible wand to direct the Cooling Coil Coating over the entire evaporator core and
surrounding gasket surfaces.
- When the application is complete, install the blower motor blower motor control module (blower
motor control module).
Application Through Blower Motor Opening
- Remove the blower motor. Refer to the applicable blower motor removal procedure in SI.
- Clean any debris or foreign material from inside the HVAC module and on the evaporator core
surface.
- Apply the Cooling Coil Coating directly to the evaporator core through the blower motor opening.
- Use the flexible wand to direct the Cooling Coil Coating over the entire evaporator core and
surrounding gasket surfaces.
- When the application is complete, install the blower motor.
Application Through a Hole in the HVAC Module
- If neither of the two previous application methods are available, it may be necessary to drill a hole
in the HVAC module.
- Locate an area of the HVAC module between the blower motor and the evaporator core. Drill a 10
mm (3/8 in) hole in the HVAC module. Use caution to keep the drill clear of the evaporator core and
the blower motor fan.
- With the air distribution vents closed and the blower motor fan speed on HIGH, insert the
applicator tool into the hole and spray the Cooling Coil Coating into the airstream toward the
evaporator core.
- Use a GM approved RTV sealant to plug the hole in the HVAC module.
9. After the Cooling Coil Coating application is complete, start and run the vehicle for approximately
10 minutes, with the compressor disabled,
HVAC mode set to Recirculate/Max, heat set to full warm, blower motor fan speed on high, and
one window open approximately 12 mm (1/2 in). This cures the Cooling Coil Coating onto the
evaporator core surface.
10. While the engine is running, rinse the applicator tool with warm water to prolong the life of the
tool. Be sure to spray warm water through the
nozzle to rinse out any residual Cooling Coil Coating still in the capillary pick up tube, otherwise it
will dry and clog the applicator tool. Also remove the small green valve from the bottle cap and
rinse it thoroughly while rolling it between two fingers and then reinstall it. If this valve is clogged ,
the Cooling Coil Coating will not flow through the applicator tool.
11. Shut off the engine and enable the compressor again. 12. Verify proper HVAC system
operation. 13. Remove the protective cover from inside the vehicle. 14. Remove the drain pan from
underneath the vehicle. 15. Reinstall the cabin air filter if necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 99-01-39-004C > Jun > 09 > A/C - Musty Odors
Emitted From (HVAC) System > Page 8106
Parts Information
Important The Cooling Coil Coating listed below is the only GM approved product for use under
warranty as an evaporator core disinfectant and for the long term control of evaporator core
microbial growth.
Warranty Information
For vehicles repaired under warranty, use the table above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates
Evaporator Core: All Technical Service Bulletins A/C - Odor at Start up in Humid Climates
File In Section: 1 - HVAC
Bulletin No.: 53-12-12A
Date: December, 1996
Subject: Air Conditioning Odor at Start Up in Humid Climates (Disinfect Evaporator Core, Install
Delayed Blower Control Package)
Models: 1993-96 Passenger Cars (Except GEO) 1993-96 Light Duty Models (Except Tracker)
This bulletin is being revised to update the wiring diagrams, add the Corvette (with RPO C60) and
delete medium/heavy duty trucks. Please discard Corporate Bulletin Number 53-12-12 (Section 1 HVAC).
Condition
Some owners may comment on odors emitted from the air conditioning system, primarily at start up
in hot, humid climates.
Cause
This odor may be the result of microbial growth on the evaporator core. When the blower motor fan
is turned on, the microbial growth may release an unpleasant musty odor into the passenger
compartment.
Correction
To remove odors of this type, it is necessary to eliminate the microbial growth and prevent its
recurrence. To accomplish this, these two procedures must be completed.
^ Deodorize the evaporator core using Deodorizing Aerosol Kit, P/N 12377951 (AC Delco 15-102).
^ Install the new A/C Delayed Blower Control Package, P/N 12370470, (AC Delco 15-8632).
The blower control package will enable the blower to run at high speed for five (5) minutes. It will
do so approximately fifty (50) minutes after the ignition has been turned off if the compressor had
been engaged for four (4) or more minutes prior to shutting off engine. By doing so, the evaporator
case and core are dried out, reducing the chances of a recurring A/C odor.
Procedure
1. Visually inspect the air conditioning evaporator drain hose for obstructions or working condition.
2. Apply deodorizing aerosol as described in the instructions supplied with the kit. Once the
deodorizer has been applied, some of the mixture may overflow from the drain hose.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8111
3. The chart identifies specific instructions for each vehicle. This chart will identify the proper
deodorizing procedure, template and wiring diagram. Deodorizing the evaporator case can easily
be done by removing the blower motor resistor and tape off opening. The nozzle can now be
inserted through a pierced hole in the tape to deodorize the evaporator case. For some of the
vehicles specified below, a drilling procedure is identified in the deodorizing instructions. This type
of alternative procedure and others can be done by using the referenced templates in the chart.
4. Complete detailed installation instructions are supplied with the blower control package.
Important:
A. 1996 ONLY (Use blower resistor location for drilling procedure)
B. 1994-1996 ONLY
Refer to appropriate Service Manual for enabling afterblow feature through on-board diagnostics.
Parts Information
Parts are currently available from GMSPO.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8112
For vehicles repaired under warranty, use as shown.
Figure 1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8113
Figure 2
Figure 3
Figure 4
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8114
Figure 5
Figure 6
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8115
Figure 7
Figure 8
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8116
Figure 9
Figure 10
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8117
Figure 11
Figure 12
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8118
Figure 13
Figure 14
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8119
Figure 15
Figure 16
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8120
Figure 17
Figure 18
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8121
Figure 19
Figure 20
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8122
Figure 21
Figure 22
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8123
Figure 23
Figure 24
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8124
Figure 25
Figure 26
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > All Technical Service Bulletins for Evaporator Core: > 531212A > Dec > 96 > A/C - Odor at Start up in
Humid Climates > Page 8125
Figure 27
Figure 28
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Page 8126
Evaporator Core: Service and Repair
EVAPORATOR ASSEMBLY
Tube And Hose Attachment At Evaporator Assembly
REMOVE OR DISCONNECT
1. Refrigerant.
^ Recover refrigerant. See: Service and Repair
2. Hose assembly (9) at evaporator assembly (1).
A. Remove nut (43) holding hose assembly (9) to evaporator outlet port. B. Pull hose assembly (9)
forward to remove it. C. Seal open end of hose assembly (9) with tape or an approved plastic cap
to prevent dirt or moisture contamination. D. If you do not intend to proceed immediately to the
following step, seal open evaporator outlet port with tape or an approved plastic cap. E. Discard
seal (44).
3. Evaporator tube assembly (10) at evaporator assembly (1).
A. Remove nut (39) holding tube assembly (10) to evaporator inlet port. B. Pull tube assembly (10)
forward to remove it. C. Seal open evaporator inlet port with tape or an approved plastic cap to
prevent dirt or moisture contamination. D. Seal opened end of tube assembly (10) with tape or an
approved plastic cap to prevent dirt or moisture contamination. E. Discard seal (40).
4. Studs (42) using a female E-7 TORX® socket. 5. Heater and air conditioning evaporator module
lower case. 6. Evaporator mounting bracket bolt/screw and bracket. 7. Evaporator assembly (1).
^ Slide evaporator assembly (1) rearward, then down, to remove it.
INSTALL OR CONNECT
1. Evaporator assembly (1). 2. Evaporator mounting bracket and bolt/screw.
TIGHTEN ^
Bolt/screw to 1.9 Nm (17 lb. in.).
3. Heater and air conditioning evaporator module lower case. 4. Refrigerant oil.
^ Add 90 ml (3 fluid ounces)of fresh polyalkylene glycol (PAG) refrigerant oil GM P/N 12345923, if
evaporator assembly (1) was removed.
5. Studs (42) using a female E-7 TORX® socket. 6. Tube assembly (10) to evaporator inlet port.
A. Remove tape or cap from the open end of evaporator inlet port and tube assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Evaporator Core > Component Information > Technical
Service Bulletins > Page 8127
B. Coat a new seal (40) with clean mineral base 525 viscosity refrigerant oil GM P/N 12301108 or
equivalent and install it. C. Install the tube assembly (10) to evaporator inlet port. D. Install nut (39)
at evaporator inlet port.
TIGHTEN ^
Nut (39) to 16 Nm (12 lb. ft.).
7. Hose assembly (9) to evaporator outlet port.
A. Remove tape or cap from open end of evaporator outlet port and hose assembly. B. Coat a new
seal (44) with clean mineral base 525 viscosity refrigerant oil GM P/N 12301108 or equivalent and
install it. C. Install hose assembly (9) to evaporator outlet port. D. Install accumulator hose nut (43)
at the evaporator outlet port.
TIGHTEN ^
Accumulator hose nut (43) to 16 Nm (12 lb. ft.).
8. Evacuate and recharge A/C system. See: Service and Repair 9. Leak-test fittings.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Expansion Block/Orifice Tube > Component Information >
Locations
Expansion Block/Orifice Tube: Locations
Expansion Tube
Expansion Tube
The plastic tube, also called the orifice tube, is in the enlarged portion at the end of the condenser
outlet pipe. Located between the condenser and evaporator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Expansion Block/Orifice Tube > Component Information >
Locations > Page 8131
Expansion Block/Orifice Tube: Service and Repair
Expansion Tube
Expansion Tube
Remove or Disconnect
Tool Required: J 26549-E Expansion Tube Remover
1. Recover refrigerant. 2. Battery negative cable 3. Condenser-to-evaporator tube fitting.
A. Seal open end of evaporator tube with tape or an approved plastic cap to prevent dirt or
moisture contamination. B. Discard seal (34).
4. Expansion tube (14) with J 26549-E from condenser outlet pipe.
^ If expansion tube (14) is restricted or plugged, and is difficult to remove, the following procedure
is recommended:
a. Remove as much residue as possible.
b. Carefully apply heat with heat gun, such as a hair dryer or an epoxy dryer near open end of
condenser outlet pipe. Do not overheat pipe.
c. While applying heat, grip expansion tube (14) with J 26549-E and use a twisting push-pull motion
to loosen impacted expansion tube (14)
and remove it.
Clean
^ Expansion tube (14), if it is to be reused.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Expansion Block/Orifice Tube > Component Information >
Locations > Page 8132
A. Blow off any metal chips, flakes, slivers and other contaminants with air hose. B. Clean
expansion tube (14) in solvent and dry it.
Inspect
^ Expansion tube (14), if it is to be reused.
a. Discard if plastic frame is broken.
b. Discard if filter screen is torn, damaged or plugged with fine gritty material.
c. Discard if brass orifice tube is damaged or plugged.
Install or Connect
1. Expansion tube (14).
A. Coat expansion tube seal with mineral base 525 viscosity refrigerant oil. B. Insert expansion
tube (14) into open end of condenser outlet pipe as shown in Figure 19. Install expansion tube (14)
until it stops, indicating
proper seal seating.
2. Seal (34) to evaporator tube (10).
^ Coat new seal (34) with mineral base 525 viscosity refrigerant oil GM P/N 12301108 and fit onto
evaporator tube (10).
3. Condenser-to~evaporator tube fitting.
Tighten
^ Condenser-to-evaporator tube fitting to 24 Nm (18 lb. ft.).
4. Battery negative cable. 5. Charge A/C system. 6. Leak test fittings.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Heater Core > Component Information > Technical Service
Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators
Heater Core: Technical Service Bulletins Cooling System, A/C - Aluminum Heater Cores/Radiators
INFORMATION
Bulletin No.: 05-06-02-001A
Date: July 16, 2008
Subject: Information On Aluminum Heater Core and/or Radiator Replacement
Models: 2005 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2003-2005
HUMMER H2
Supercede:
This bulletin is being revised to update the Warranty Information. Please discard Corporate Bulletin
Number 05-06-02-001 (Section 06 - Engine/Propulsion System).
Important:
2004-05 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX-COOL(R). Refer to the
flushing procedure explained later in this bulletin.
The following information should be utilized when servicing aluminum heater core and/or radiators
on repeat visits. A replacement may be necessary because erosion, corrosion, or insufficient
inhibitor levels may cause damage to the heater core, radiator or water pump. A coolant check
should be performed whenever a heater core, radiator, or water pump is replaced. The following
procedures/ inspections should be done to verify proper coolant effectiveness.
Caution:
To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot.
The cooling system will release scalding fluid and steam under pressure if the radiator cap or surge
tank cap is removed while the engine and radiator are still hot.
Important:
If the vehicle's coolant is low, drained out, or the customer has repeatedly added coolant or water
to the system, then the system should be completely flushed using the procedure explained later in
this bulletin.
Technician Diagnosis
^ Verify coolant concentration. A 50% coolant/water solution ensures proper freeze and corrosion
protection. Inhibitor levels cannot be easily measured in the field, but can be indirectly done by the
measurement of coolant concentration. This must be done by using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale), or equivalent, coolant tester. The Refractometer
uses a minimal amount of coolant that can be taken from the coolant recovery reservoir, radiator or
the engine block. Inexpensive gravity float testers (floating balls) will not completely analyze the
coolant concentration fully and should not be used. The concentration levels should be between
50% and 65% coolant concentrate. This mixture will have a freeze point protection of -34 degrees
Fahrenheit (-37 degrees Celsius). If the concentration is below 50%, the cooling system must be
flushed.
^ Inspect the coolant flow restrictor if the vehicle is equipped with one. Refer to Service Information
(SI) and/or the appropriate Service Manual for component location and condition for operation.
^ Verify that no electrolysis is present in the cooling system. This electrolysis test can be performed
before or after the system has been repaired. Use a digital voltmeter set to 12 volts. Attach one test
lead to the negative battery post and insert the other test lead into the radiator coolant, making sure
the lead does not touch the filler neck or core. Any voltage reading over 0.3 volts indicates that
stray current is finding its way into the coolant. Electrolysis is often an intermittent condition that
occurs when a device or accessory that is mounted to the radiator is energized. This type of current
could be caused from a poorly grounded cooling fan or some other accessory and can be verified
by watching the volt meter and turning on and off various accessories or engage the starter motor.
Before using one of the following flush procedures, the coolant recovery reservoir must be
removed, drained, cleaned and reinstalled before refilling the system.
Notice:
^ Using coolant other than DEX‐COOL(R) may cause premature engine, heater core or
radiator corrosion. In addition, the engine coolant may require changing sooner, at 30,000 miles
(50,000 km) or 24 months, whichever occurs first. Any repairs would not be covered by your
warranty. Always use DEX‐COOL(R) (silicate free) coolant in your vehicle.
^ If you use an improper coolant mixture, your engine could overheat and be badly damaged. The
repair cost would not be covered by your warranty. Too much water in the mixture can freeze and
crack the engine, radiator, heater core and other parts.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Heater Core > Component Information > Technical Service
Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 8137
Flushing Procedures using DEX-COOL(R)
Important:
The following procedure recommends refilling the system with DEX-COOL(R), P/N 12346290 (in
Canada, use P/N 10953464), GM specification 6277M. This coolant is orange in color and has a
service interval of 5 years or 240,000 km (150,000 mi). However, when used on vehicles built prior
to the introduction of DEX-COOL(R), maintenance intervals will remain the same as specified in the
Owner's Manual.
^ If available, use the approved cooling system flush and fill machine (available through the GM
Dealer Equipment Program) following the manufacturer's operating instructions.
^ If approved cooling system flush and fill machine is not available, drain the coolant and dispose of
properly following the draining procedures in the appropriate Service Manual. Refill the system
using clear, drinkable water and run the vehicle until the thermostat opens. Repeat and run the
vehicle three (3) times to totally remove the old coolant or until the drained coolant is almost clear.
Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with
DEX‐COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M,
following the refill procedures in the appropriate Service Manual.
If a Service Manual is not available, fill half the capacity of the system with 100% DEX-COOL(R),
P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. Then slowly add clear,
drinkable water (preferably distilled) to the system until the level of the coolant mixture has reached
the base of the radiator neck. Wait two (2) minutes and reverify the coolant level. If necessary, add
clean water to restore the coolant to the appropriate level.
Once the system is refilled, reverify the coolant concentration using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. The concentration
levels should be between 50% and 65%.
Flushing Procedures using Conventional Silicated (Green Colored) Coolant
Important:
2004-2005 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX‐COOL(R).
The Aveo and Wave are filled with conventional, silicated engine coolant that is blue in color.
Silicated coolants are typically green in color and are required to be drained, flushed and refilled
every 30,000 miles (48,000 km). The Aveo and Wave are to be serviced with conventional, silicated
coolant. Use P/N 12378560 (1 gal) (in Canada, use P/N 88862159 (1 L). Refer to the Owner's
Manual or Service Information (SI) for further information on OEM coolant.
Important:
Do not mix the OEM orange colored DEX-COOL(R) coolant with green colored coolant when
adding coolant to the system or when servicing the vehicle's cooling system. Mixing the orange and
green colored coolants will produce a brown coolant which may be a customer dissatisfier and will
not extend the service interval to that of DEX-COOL(R). Conventional silicated coolants offered by
GM Service and Parts Operations are green in color.
^ If available, use the approved cooling system flush and fill machine (available through the GM
Dealer Equipment Program) following the manufacturer's operating instructions.
^ If approved cooling systems flush and fill machine is not available, drain coolant and dispose of
properly following the draining procedures in appropriate Service Manual. Refill the system using
clear, drinkable water and run vehicle until thermostat opens. Repeat and run vehicle three (3)
times to totally remove old coolant or until drained coolant is almost clear. Once the system is
completely flushed, refill the cooling system to a 50%-60% concentration with a good quality
ethylene glycol base engine coolant, P/N 12378560, 1 gal (in Canada, use P/N 88862159 1 L),
conforming to GM specification 1825M, or recycled coolant conforming to GM specification 1825M,
following the refill procedures in the appropriate Service Manual.
If a Service Manual is not available, fill half the capacity of the system with 100% good quality
ethylene glycol base (green colored) engine coolant, P/N 12378560 1 gal., (in Canada, use P/N
88862159 1 L) conforming to GM specification 1825M. Then slowly add clear, drinkable water
(preferably distilled) to system until the level of the coolant mixture has reached the base of the
radiator neck. Wait two (2) minutes and recheck coolant level. If necessary, add clean water to
restore coolant to the appropriate level.
Once the system is refilled, recheck the coolant concentration using a Refractometer J 23688
(Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. Concentration levels
should be between 50% and 65%.
Parts Information
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Heater Core > Component Information > Technical Service
Bulletins > Cooling System, A/C - Aluminum Heater Cores/Radiators > Page 8138
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Heater Core > Component Information > Service and Repair
> With Air Conditioning
Heater Core: Service and Repair With Air Conditioning
Fig. 21 Heater Core & Evaporator Core
1. Disconnect battery ground cable, then drain cooling system. 2. Remove heater outlet attaching
screw. 3. Disconnect heater core pipe fittings, then disengage pipe from fitting. 4. Remove
righthand instrument insulator panel attaching screws, then pull panel rearward to disconnect. 5.
Remove instrument panel lower reinforcement attaching nut and screw. 6. Disconnect lower
evaporator case vacuum electrical connectors. 7. Remove righthand pillar trim finish panel, then
roll carpet back to gain access. 8. Remove seven lower evaporator case attaching screws, then
remove lower evaporator case. 9. Remove heater core attaching straps and screws, then pull
heater core rearward working heater tubes out of seal, Fig. 21.
10. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Heater Core > Component Information > Service and Repair
> With Air Conditioning > Page 8141
Heater Core: Service and Repair Without Air Conditioning
1. Disconnect battery ground cable and drain cooling system. 2. Disconnect heater hoses from
heater core. Plug core outlets to prevent coolant spillage. 3. Disconnect electrical connections at
blower motor and resistor. 4. Detach heater wiring from clip at blower housing cover. 5. Remove
blower housing cover attaching screws, then remove blower housing cover. 6. Remove heater
core. 7. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment
Refrigerant: Technical Service Bulletins A/C - Refrigerant Recovery/Recycling/Equipment
Bulletin No.: 08-01-38-001
Date: January 25, 2008
INFORMATION
Subject: Information On New GE-48800 CoolTech Refrigerant Recovery/Recharge Equipment
Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2008 and
Prior HUMMER H2, H3 2005-2008 Saab 9-7X
Attention:
This bulletin is being issued to announce the release of GM approved Air Conditioning (A/C)
Refrigerant Recovery and Recharging Equipment that meets the new Society of Automotive
Engineers (SAE) J2788 Refrigerant Recovery Standards. The ACR2000 (J-43600) cannot be
manufactured in its current state after December 2007 and will be superseded by GE-48800.
The new J2788 standard does not require that GM Dealers replace their ACR2000 units.
ACR2000's currently in use are very capable of servicing today's refrigerant systems when used
correctly and can continue to be used. Details regarding the new SAE J2788 standard are outlined
in GM Bulletin 07-01-38-004.
Effective February 1 2008, new A/C Refrigerant Recovery/Recharging equipment (P/N GE-48800)
will be released as a required replacement for the previously essential ACR2000 (J-43600). This
equipment is SAE J2788 compliant and meets GM requirements for A/C Refrigerant System
Repairs on all General Motors vehicles, including Hybrid systems with Polyolester (POE)
refrigerant oil. This equipment will not be shipped as an essential tool to GM Dealerships.
In addition, this equipment is Hybrid compliant and designed to prevent oil cross contamination
when servicing Hybrid vehicles with Electric A/C Compressors that use POE refrigerant oil.
The ACR2000 (J-43600) will need to be retrofitted with a J-43600-50 (Hose - ACR2000 Oil Flush
Loop) to be able to perform Hybrid A/C service work. All Hybrid dealers will receive the J-43600-50,
with installation instructions, as a component of the Hybrid essential tool package. Dealerships that
do not sell Hybrids, but may need to service Hybrids, can obtain J-43600-50 from SPX Kent Moore.
Refer to GM Bulletin 08-01-39-001 for the ACR2000 Hose Flush procedure.
The High Voltage (HV) electric A/C compressor used on Two Mode Hybrid vehicles uses a
Polyolester (POE) refrigerant oil instead of a Polyalkylene Glycol (PAG) synthetic refrigerant oil.
This is due to the better electrical resistance of the POE oil and its ability to provide HV isolation.
Failure to flush the hoses before adding refrigerant to a Hybrid vehicle with an electric A/C
compressor may result in an unacceptable amount of PAG oil entering the refrigerant system. It
may cause a Battery Energy Control Module Hybrid Battery Voltage System Isolation Lost
Diagnostic Trouble Code (DTC P1AE7) to be set. Additionally, the A/C system warranty will be
voided.
Warranty Submission Requirements
The Electronically Generated Repair Data (snapshot summary) and printer functions have been
eliminated from the GE-48800. The VGA display and temperature probes were eliminated to
reduce equipment costs. As a result, effective immediately the 18 digit "Snapshot/Charge
Summary" code is no longer required for Air Conditioning (A/C) refrigerant system repairs that are
submitted for warranty reimbursement. The charge summary data from before and after system
repairs will continue to required, but documented on the repair order only. Both high and low
pressures and the recovery and charge amounts should be noted during the repair and entered on
the repair order. If using ACR2000 (J-43600), the "Snapshot/Charge Summary" printouts should
continue to be attached to the shops copy of the repair order.
The labor codes that are affected by this requirement are D3000 through D4500.
Disclaimer
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Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8146
Refrigerant: Technical Service Bulletins A/C - Contaminated R134A Refrigerant
Bulletin No.: 06-01-39-007
Date: July 25, 2006
INFORMATION
Subject: Contaminated R134a Refrigerant Found on Market for Automotive Air-Conditioning
Systems
Models: 2007 and Prior GM Passenger Cars and Trucks (including Saturn) 2007 and Prior
HUMMER H2, H3 2007 and Prior Saab 9-7X
Attention:
This bulletin should be directed to the Service Manager as well as the Parts Manager.
Commercially Available Contaminated R134a Refrigerant
Impurities have been found in new commercially available containers of R134a. High levels of
contaminates may cause decreased performance, and be detrimental to some air-conditioning
components. Accompanying these contaminates has been high levels of moisture.
Tip:
Excessive moisture may cause system concerns such as orifice tube freeze-up and reduced
performance.
Industry Reaction: New Industry Purity Standards
Due to the potential availability of these lower quality refrigerants, the Society of Automotive
Engineers (SAE), and the Air Conditioning and Refrigeration Industry (ARI) are in the process of
instituting reliable standards that will be carried on the labels of future R134a refrigerant containers.
This identifying symbol will be your assurance of a product that conforms to the minimum standard
for OEM Automotive Air-Conditioning use.
How Can You Protect Yourself Today?
It is recommended to use GM or ACDelco(R) sourced refrigerants for all A/C repair work. These
refrigerants meet General Motors own internal standards for quality and purity, insuring that your
completed repairs are as good as the way it left the factory.
Parts Information
The part numbers shown are available through GMSPO or ACDelco(R). The nearest ACDelco(R)
distributor in your area can be found by calling 1-800-223-3526 (U.S. Only).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8147
Disclaimer
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Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8148
Refrigerant: Technical Service Bulletins A/C - Refrigerant Recovery/Recharge Equipment
File In Section: 01 - HVAC
Bulletin No.: 99-01-38-006A
Date: May, 2000
WARRANTY ADMINISTRATION
Subject: J-43600 ACR 2000 Essential Refrigerant Recovery/Recharge Equipment
Models: 1993-2000 Passenger Cars and Light Duty Trucks with R-134a Refrigerant
This bulletin is being revised to change the effective date and to update the text. Please discard
Corporate Bulletin Number 99-01-38-006 (Section 01 - HVAC).
Effective June 1, 2000, the use of J-43600 ACR 2000 will be required on all repairs that require A/C
system recovery and are reimbursable by GM. Additionally, GM highly recommends that J-43600
ACR 2000 be used on all GM cars and trucks for customer paid A/C repairs.
Important:
Also effective June 1, 2000, the "Add" time for all air conditioning recovery is revised to 0.5 hours
for front systems and 0.7 hours for front/rear dual systems (RPO C69 or C34). After June 1, 2000,
all air conditioning claims submitted with the 0.9 hours "Add" time will be rejected for "labor hours
excessive".
After the completion of repairs (charging), the ACR 2000 will prompt the user to perform a snapshot
of the air conditioning system operating data. The snapshot includes:
^ Maximum high side pressure.
^ Minimum low side pressure.
^ Duct outlet temperatures (2).
^ Refrigerant purity information.
This information is captured on a paper printout and in a warranty code.
For all GM paid repairs, the paper printout should be attached to the shop copy of the repair order.
The warranty code must be submitted in the warranty claim information in the comments field. The
code enables the reporting of valuable information about the repair to GM for product quality
improvement. Claims submitted without this information may be subject to review and subsequent
debit.
The required use of J-43600 ACR 2000 raises the question of the acceptable uses for any existing
recovery/recycle equipment that GM dealers are currently using. GM recognizes that many of the
previously essential ACR4's are reaching the end of their useful life. There are several alternatives
for existing equipment that may be considered:
^ Use the existing equipment as customer paid recovery only equipment. Example: Collision repair
area.
^ Use the existing equipment as a scavenger unit for contaminated A/C systems.
^ Sell the existing units to repair facilities outside the GM dealer network.
^ Discontinue the use of the existing units if the repair/maintenance costs exceed the value of the
equipment.
^ Donate the existing equipment to local technical schools.
^ Dedicate the ACR4 to A/C system flushing, using the J-42939 Flush Adapter.
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Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8149
Disclaimer
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Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8150
Technical Service Bulletin # 631209 Date: 960501
A/C - R12 or R134a Service Recommendations
File In Section: 1 - HVAC
Bulletin No.: 63-12-09
Date: May, 1996
INFORMATION
Subject: Service Issues for Vehicles with R12 or R134a Air Conditioning Systems
Models: 1988-96 Passenger Cars and Trucks
R12 Service Recommendations
As you know, production of R12 refrigerant ceased on December 31, 1995. Although R12 will no
longer be manufactured, there is a reserve supply of R12 available. This reserve, along with strict
A/C repair service adherence to proper refrigerant recycling procedures, should assure continued
availability to meet consumers' needs.
R12 can and should continue to be used to service vehicles built with R12 A/C systems as long as
it is available. If R12 is no longer available or affordable, a system retrofit utilizing R134a is
recommended. R134a IS THE ONLY SUBSTITUTE REFRIGERANT RECOMMENDED BY GM
FOR USE IN GM VEHICLE A/C SYSTEMS, AND THEN ONLY AFTER FOLLOWING THE
PROPER RETROFIT PROCEDURES FOR THE SPECIFIC MODEL. All new vehicle
manufacturers have chosen R134a for retrofit. One of the key reasons is to protect both the service
industry and consumers from the high costs that would result from purchasing equipment
necessary to service multiple refrigerants. This position also reduces the threat of recycled
refrigerant contamination.
GM currently offers a simple, low cost R12 to R134a retrofit on many of its late model, front wheel
drive passenger cars. Dealers should discuss this capability with owners of these specific models,
listed in Retrofit Corporate Bulletin # 43-12-07D, whenever a repair to the A/C refrigerant system is
required. Early retrofit of these specific models will aid in prolonging availability of the R12 supply
and provide dealer service technicians the opportunity to become more familiar with the proper
procedures for performing a retrofit.
Remember - R12 and R134a refrigerant are not interchangeable! They cannot be mixed together.
In fact, despite the claims of some refrigerant manufacturers, no proposed R12 refrigerant
substitute can be added to, mixed with or used to "top off" an R12 system. Under provisions of law
covering the service of refrigerants, mixing dissimilar refrigerant products during service is
prohibited.
To Summarize GM R12 Service Policy
1. Service R12 vehicles with good quality new or recycled R12 as long as it is available.
2. Purchase R12 from a reliable supplier. GMSPO has a supply of high quality R12 available.
Dealers are requested to use only R12 supplied by GMSPO for warranty repairs. This high quality
refrigerant will insure system performance and avoid the possibility of introducing contaminated
material into the customer's A/C system.
3. Carefully test recovered R12 using the PureGuard monitor. On recovery equipment not
protected by the PureGuard, always test the recovery cylinder prior to recharging a vehicle A/C
system.
4. Discuss the R12 to R134a retrofit option with owners of GM vehicles listed in Retrofit Corporate
Bulletin # 43-12-07D. Provide owner with a copy of the pamphlet "Converting Your Auto Air
Conditioning System to Use the New Refrigerant".
5. Become familiar with retrofit procedures and exercise care in the handling of dissimilar
refrigerants to prevent contamination.
R134A Service Recommendations
When servicing a previously retrofitted vehicle, there is concern that if all of the R12 is not
completely removed prior to the retrofit procedure, it could contaminate your R134a equipment and
recovery tank when a subsequent A/C repair is performed. Although the number of retrofits being
performed today is minimal, the volume will increase as R12 prices rise.
GM Service Technology Group is in the process of field testing a new R134a refrigerant purity
tester similar to the PureGuard R12 refrigerant tester you now use. This new tool will mount to your
ACR4 R134a Recovery Recycle and Recharge cart and sample all R134a refrigerant prior to
recovery. It is expected that testing of this tool will be completed this year.
This new tool, the Pureguard 2, will also test vehicles and your recycle tank for air contamination,
which is threatening A/C system performance. High levels of air have been found in the recovery
tanks on a number of R12 and R134a recovery carts. Air contamination is caused by improper
recovery
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Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8151
procedures and short-cutting refrigerant recycling times. Use the following procedure for testing
and correcting air contamination in your A/C service equipment.
1. Make certain that the ACR4 equipment has not been used for at least 12 hours. It is
recommended that the equipment be left in an area where the temperature will remain constant
overnight to allow the temperature of the refrigerant in the tank to stabilize.
2. Record the surrounding air temperature next to the ACR4 refrigerant tank.
Important:
A major assumption is that the ambient air temperature next to the tank represents the refrigerant
temperature in the tank. Failure to take care in measuring the temperature could result in
unnecessary work.
3. Close both liquid (blue) and vapor (red) valves on the ACR4 tank.
4. Disconnect low side (blue) service hose from the back of the ACR4.
5. Slowly disconnect the tank vapor hose (red) from the back of the ACR4 and connect it to the low
side service port.
6. Open the vapor (red) valve on the tank and record the tank pressure on the low side gage.
7. Restore hoses to the original position.
8. Referring to the Table, find the ambient temperature measured in Step 2. Compare the pressure
reading from Step 6 to the "maximum allowable pressure". If the pressure reading from Step 6 is
less than the "maximum allowable pressure", no further action is necessary.
Important:
The closer the tank pressure is to the desired tank pressure, the better the A/C system will perform.
9. If the pressure reading from Step 6 exceeds the maximum allowable pressure from the Table,
open both tank valves and operate the ACR4 through 4 or 5 evacuation cycles. This will activate
the automatic air purge to lower the tank pressure.
Important:
Station should not be connected to vehicle.
10. Repeat the tank pressure checking procedure the next day to determine if the pressure has
been reduced to acceptable levels. If the tank pressure has been reduced but is not acceptable,
cycle with ACR4 through more evacuation cycles and recheck the next day. Continue process until
acceptable pressure is obtained. If the tank pressure is not reduced through the evacuation cycling,
then Kent-Moore should be contacted at 1-800-345-2233.
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Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8152
Refrigerant: Technical Service Bulletins A/C - R134a Leak Detection With Tracer Dye
File In Section: 1 - HVAC
Bulletin No.: 43-12-15
Date: November, 1994
Subject: R134a Leak Detection with Tracer Dye
Models: All 1993-95 Vehicles with OEM R134a Systems All R12 Vehicles Retrofitted to R134a
Systems
R134a refrigerant is uniquely different from R12 refrigerant and requires some changes in the
repair methods, tools and materials used in A/C service. Two important differences between R134a
and R12 which affect the technicians ability to locate refrigerant leaks are:
1. The R134a molecule is smaller than the R12 molecule and therefore will leak through smaller
openings. For the same size opening the smaller R134a molecule will leak out faster than the R12.
2. R134a refrigerant does not contain chlorine which the older R12 electronic leak detectors found
very easy to identify. Many of today's electronic leak detectors have difficulty locating small R134a
refrigerant leaks.
In order to insure the highest quality in A/C system service, the J 39400 electronic leak detector
was released as an essential tool for all GM dealers. This is the only refrigerant leak detector
approved by GM for service on R134a vehicles. If maintained properly (Reference Bulletin No.
431218) and used in accordance with Service Manual procedures, the J 39400 will provide the
most accurate and efficient method of locating R134a refrigerant leaks under most conditions.
If the technician cannot find the leak with the J 39400 and the system is known to have lost charge,
a new fluorescent leak tracer dye Kent-Moore* P/N J 41447, has been released that mixes with the
R134a PAG oil. This dye is detectable through the use of an ultraviolet (black) light and glows
yellow/green at the leak location (similar to using dye in engine leak detection). J 41447 IS THE
ONLY APPROVED DYE BY GENERAL MOTORS. Not all R134a dyes are compatible with GM's
PAG oil. Some dyes decrease the oil viscosity or chemically react with the oil. Use of alternate
products may affect system reliability and cause premature compressor failure.
Note:
THIS DYE IS NOT TO BE USED IN R-12 SYSTEMS.
Unlike mineral oil, the R134a PAG oil has special properties the technician should keep in mind.
1. PAG oil is water soluble and traces of PAG oil found at leaking joints are subject to "washing
out". Condensation on refrigerant lines or the evaporator core may wash the PAG oil and leak dye
off the line or off the core and out the condensate drain. This can make some leaks harder to find
using the dye detector. Fluorescence at the drain opening would indicate a core leak.
2. Use of the R134a tracer dye requires time. Depending upon the leak rate, it may take between
15 minutes and 7 days for the leak to become visible.
3. The dye, mixed with the PAG oil, is retained in the system and is detectable for 2+ years. Do not
double or triple charge the system with dye as this may cause reliability concerns. Use only the 1/4
oz. charge.
The dye has a refrigerant leak detection notice sticker included with the package. Complete the
sticker information and place near the charge label.
Dye Injection R-134a dye can be injected two ways:
1. With the A/C system charged, use the instructions provided with the new R134a leak dye
injection tool, J 41436.
2. With A/C system discharged, add dye into the newly replaced component assembly.
It is important to note that it is normal to find oil traces at the compressor shaft seal during
compressor operation, some oil will hydraulically seep past the shaft seal. This does not mean that
the shaft seal is defective or that the refrigerant has leaked. Refrigerant leaks at the shaft seal
should be verified with the electronic leak detector (J 39400) following the procedure detailed in the
Service Manual. If, however, the amount of oil is excessive, the shaft seal is suspect and should be
replaced. (For example, refrigerant oil has coated the clutch plate edge at gap between clutch and
pulley, or oil slinging has occurred-oil line shows on underside of hood, etc.).
Also, after working on A/C components with dye, it is important to wipe the joint and/or access
ports clean of any residual dye with GM solvent (GM
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > A/C - Refrigerant Recovery/Recycling/Equipment > Page 8153
P/N 1050436) to prevent false diagnosis at a later point.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Parts Information GM solvent, P/N 1050436, is currently available from GMSPO.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Technical Service
Bulletins > Page 8154
Refrigerant: Specifications
Refrigerant Capacity, Lbs. ...................................................................................................................
................................................ 0.79 kg. (1 lb. 12 oz.)
Refrigerant Type ..................................................................................................................................
...................................................................... R-134a
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Description and
Operation > Refrigerant R-12
Refrigerant: Description and Operation Refrigerant R-12
DESCRIPTION
It is colorless and odorless both as a gas and a liquid. Since it boils (vaporizes) at -21.7° F, it will
usually be in a vapor state when being handled in a repair shop. But if a portion of the liquid coolant
should come in contact with the hands or face, note that its temperature momentarily will be at
least -22° F.
WARNING: Protective goggles should be worn when opening any refrigerant lines. If liquid coolant
does touch the eyes, bathe the eyes quickly in cold water, then apply a bland disinfectant oil to the
eyes. See an eye doctor.
WARNING: When checking a system for leaks with a torch type leak detector, do not breathe the
vapors coming from the flame. Do not discharge refrigerant in the area of a live flame. A poisonous
phosgene gas is produced when R-12 is burned. While the small amount of gas produced by a leak
detector is not harmful unless inhaled directly at the flame, the quantity of refrigerant released into
the air when a system is purged can be extremely dangerous if allowed to come into contact with
an open flame.
WARNING: Never allow the temperature of refrigerant drums to exceed 125° F. The excessive
increase in temperature will cause a corresponding increase in pressure which may cause the
safety plug to release or the drum to burst.
If it is necessary to heat a drum of refrigerant when charging a system, the drum should be placed
in water no hotter than 125° F. Never use a blow torch or other open flame. If possible, a pressure
release mechanism should be attached before the drum is heated.
When connecting and disconnecting service gauges on an A/C system, ensure gauge hand valves
are fully closed and that compressor service valves, if equipped, are in the back-seated (fully
counterclockwise) position. Do not disconnect gauge hoses from service port adapters, if used,
while gauges are connected to A/C system. To disconnect hoses, always remove adapter from
service port. Do not disconnect hoses from gauge manifold while connected to A/C system, as
refrigerant will be rapidly discharged.
After disconnecting gauge lines, check the valve areas to be sure service valves are correctly
seated and Schrader valves, if used, are not leaking.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant > Component Information > Description and
Operation > Refrigerant R-12 > Page 8157
Refrigerant: Description and Operation Refrigerant-134a
R-134a refrigerant is a non toxic, nonflammable, clear and odorless liquefied gas.
CAUTION: R-134a refrigerant is not compatible with R-12 refrigerant. Even small amounts of R-12
in a R-134a system will cause lubricant contamination, compressor failure or improper A/C
performance. Never add R-12 to a R-134a system.
WARNING: Avoid breathing R-134a refrigerant and lubricant vapor or mist. Exposure may irritate
eyes, nose and throat. Use only approved service equipment to discharge R-134a systems.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant Oil > Component Information > Technical
Service Bulletins > A/C - New PAG Oil
Refrigerant Oil: Technical Service Bulletins A/C - New PAG Oil
Bulletin No.: 02-01-39-004B
Date: November 16, 2005
INFORMATION
Subject: New PAG Oil Released
Models: 2006 and Prior GM Passenger Cars and Trucks (Including Saturn) 2003-2006 HUMMER
H2 2006 HUMMER H3 2005-2006 Saab 9-7X
Built With R-134a Refrigeration System
All Air Conditioning Compressor Types (Excluding R4 and A6 Type Compressors)
Supercede:
This bulletin is being revised to change the PAG oil part number used for R4 and A6 compressors
with R-134a refrigerant systems. Please discard Corporate Bulletin Number 02-01-39-004A
(Section 01 - HVAC).
All General Motors vehicles built with R-134a refrigerant systems shall now be serviced with GM
Universal PAG Oil (excluding vehicles equipped with an R4 or A6 compressor).
R4 and A6 compressors with R-134a refrigerant systems shall use PAG OIL, GM P/N 12356151
(A/C Delco part number 15-118) (in Canada, use P/N 10953486).
Important:
The PAG oil referenced in this bulletin is formulated with specific additive packages that meet
General Motors specifications and use of another oil may void the A/C systems warranty.
Use this new PAG oil when servicing the A/C system on the vehicles listed above. Oil packaged in
an 8 oz tube should be installed using A/C Oil Injector, J 45037. Refer to the HVAC Section of
Service Information for detailed information on Oil Balancing and Capacities.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant Oil > Component Information > Specifications >
Capacity Specifications
Refrigerant Oil: Capacity Specifications
Compressor Model [02] .......................................................................................................................
........................................................... HD6/HR6-HE Oil Charge (FL. Oz.) When Replacing
Component
Compressor .........................................................................................................................................
............................................................................. [03]
Evaporator ...........................................................................................................................................
................................................................................. 3 Condenser ......................................................
..............................................................................................................................................................
........ 1 Accumulator .............................................................................................................................
......................................................................................... 3.5
[02] Fixed displacement compressor. [03] Drain oil from old compressor and measure, then drain
new compressor. If more than one ounce is drained from old compressor, add same amount
to new compressor. If less than one ounce is drained from compressor, add two ounces.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant Oil > Component Information > Specifications >
Capacity Specifications > Page 8164
Refrigerant Oil: Fluid Type Specifications
REFRIGERANT OIL TYPE
^ R-134a PAG (Polyalkaline Glycol) synthetic refrigerant oil (GM Part No. 12345923) or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant Pressure Sensor / Switch, HVAC > Component
Information > Locations > A/C Compressor Pressure Cycling Switch
Refrigerant Pressure Sensor / Switch: Locations A/C Compressor Pressure Cycling Switch
Engine Harness/U/Hood Electrical Center, Right Side
Attached to A/C accumulator, RH rear of Engine Compartment
RH Rear Engine Compartment attached to A/C Accumulator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Refrigerant Pressure Sensor / Switch, HVAC > Component
Information > Locations > A/C Compressor Pressure Cycling Switch > Page 8169
Refrigerant Pressure Sensor / Switch: Locations A/C Refig Press Sensor
Component Location - Pictorial View
In High Pressure Line, below Coolant Reservoir
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Relays and Modules - HVAC > Blower Motor Relay >
Component Information > Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Relays and Modules - HVAC > Blower Motor Relay >
Component Information > Locations > Page 8174
LO Blower Relay, Rear Defog Relay And HI Blower Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Relays and Modules - HVAC > Compressor Clutch Relay >
Component Information > Locations
Compressor Clutch Relay: Locations
Underhood Electrical Center
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Air Conditioning Switch >
Component Information > Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Ambient Temperature
Sensor / Switch HVAC > Component Information > Locations > Inside Air Temperature Sensor
Ambient Temperature Sensor / Switch HVAC: Locations Inside Air Temperature Sensor
Instrument Panel Carrier, above Glove Box.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Ambient Temperature
Sensor / Switch HVAC > Component Information > Locations > Inside Air Temperature Sensor > Page 8186
Ambient Temperature Sensor / Switch HVAC: Locations Outside Air Temperature Sensor
Attached to Hood Latch Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Blower Motor Switch >
Component Information > Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Blower Motor Switch >
Component Information > Locations > Page 8190
Heater And A/C Blower Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Refrigerant Pressure
Sensor / Switch, HVAC > Component Information > Locations > A/C Compressor Pressure Cycling Switch
Refrigerant Pressure Sensor / Switch: Locations A/C Compressor Pressure Cycling Switch
Engine Harness/U/Hood Electrical Center, Right Side
Attached to A/C accumulator, RH rear of Engine Compartment
RH Rear Engine Compartment attached to A/C Accumulator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Refrigerant Pressure
Sensor / Switch, HVAC > Component Information > Locations > A/C Compressor Pressure Cycling Switch > Page 8195
Refrigerant Pressure Sensor / Switch: Locations A/C Refig Press Sensor
Component Location - Pictorial View
In High Pressure Line, below Coolant Reservoir
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Sensors and Switches - HVAC > Solar Sensor, HVAC >
Component Information > Locations
Solar Sensor: Locations
Near center of I/P Upper Trim Pad (in Defroster Grille)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Solar Sensor, HVAC > Component Information > Locations
Solar Sensor: Locations
Near center of I/P Upper Trim Pad (in Defroster Grille)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Vacuum Harness HVAC > Component Information >
Locations
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Vacuum Solenoid Valve HVAC > Component Information >
Locations
Rear View Of Center Instrument Panel (With C67 Or C68)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Heating and Air Conditioning > Vacuum Solenoid Valve HVAC > Component Information >
Locations > Page 8208
Vacuum/Electric Solenoid
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag(s) Arming and Disarming > System
Information > Service and Repair > Air Bag Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag(s) Arming and Disarming > System
Information > Service and Repair > Air Bag Disarming and Arming > Page 8215
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure
Air Bag: Technical Service Bulletins Air Bag - Module Shipping/Return Procedure
File In Section: 9 - Accessories
Bulletin No.: 31-90-04A
Date: September, 1996
Subject: Supplemental Inflatable Restraint (SIR) Module Shipping/Return Procedure
Models: 1993-97 Passenger Cars and Trucks - Equipped with Supplemental Inflatable Restraint
(SIR) Modules
EXCEPT THE MODELS AND YEARS AS LISTED
This bulletin is being revised to update the: models and years affected, the contact telephone
numbers and the hazardous classification rating. Various areas of the text and the attachments
have also been revised. Please discard Corporate Bulletin Number 319004 (Group Reference Accessories).
This bulletin outlines the return procedure for undeployed Supplemental Inflatable Restraint (SIR)
modules. Undeployed SIR modules in all vehicles (except models indicated), removed for warranty
purposes, are to be returned to Delphi Interior and Lighting Systems, General Motors Corporation.
This bulletin outlines procedures that all dealers must follow for shipping undeployed airbag
modules. This bulletin is in effect and should be retained at all times at the dealership until
superseded by a subsequent bulletin.
This return program does NOT apply to dealers in Alaska, Hawaii, US Territories, and foreign
countries. SIR modules replaced outside the continental United States should be deployed and
disposed of following the procedure outlined in Corporate Bulletin Number 319003R. All other
modules (i.e., out of warranty or car scrapped) should be disposed of per Corporate Bulletin
Number 319003R.
Important:
If a vehicle is the subject of a Preliminary Investigation (GM-1241), DO NOT ALTER the SIR
system until cleared by the Zone Service Representative. An SIR module returned following a 1241
investigation must be clearly designated by:
1. Indicating on the REPAIR ORDER copy inside the box "SUBJECT TO 1241".
2. Indicating the VIN and vehicle owner on the REPAIR ORDER.
3. Sending photocopies of the REPAIR ORDER to:
a. The appropriate Zone service Representative
b. Cigna Company GM Central Claims Unit 485 W. Milwaukee Suite 690 Detroit, MI 48202
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8220
Mailing Address: P.O. Box 02489, Detroit, MI 48202
Questions related to handling of 1241 associated SIR modules may be answered by calling: Cigna
Company - GM Central Claims Unit, 1-800-888-1491.
The U.S. Department of Transportation (DOT) Hazardous Materials Regulations classify SIR
modules as the following:
^ Proper Shipping Name: Air Bag Modules
^ Hazardous Class: Class 9 - Air Bag
Failure to comply with DOT regulations will result in civil penalties of up to $10,000 per violation or
criminal penalties of up to $25,000 per violation and imprisonment.
Return Procedure for Supplemental Inflatable Restraint Modules
(Undeployed Modules Only)
All undeployed SIR modules in all vehicles (except as indicated in the models section of this
bulletin), removed for warranty purposes, are to be returned to Delphi Interior and Lighting
Systems, General Motors. The following procedure should be followed when returning SIR
modules from any location within the continental United States.
1. Packaging Requirements
Return undeployed SIR modules in the same carton that was received with the new replacement
module. Do not use any carton that has been damaged to the extent that the product will not be
protected during the shipment. If you need a replacement carton, contact Delphi Interior and
Lighting Systems at (513) 356-2426. ENCLOSE A COPY OF THE REPAIR ORDER, detailing the
reason(s) for the SIR module replacement.
Close and secure the carton with packaging tape (transparent tape is recommended). All existing
labels and markings on the carton must be visible.
Important:
DO NOT staple container. DO NOT cover any portion of the black and white "Class 9" label or any
markings on the carton.
2. Package Labels and Markings
Add the names and addresses for the consignee and the consignor. The method of closure cannot
interfere with the labels or the markings on the package (see Attachments "A" - Driver Side, and
"D" - Passenger Side).
3. Shipping Paper (UPS Hazardous Material Label and Shipper's Certification)
The following items on the shipping papers must be completed with the same information as
enclosed with the replacement SIR module when received: proper shipping name, hazard class,
identification number, packaging group number, "EX" number, and emergency response telephone
number. The remaining information should be completed in accordance with Attachments "B" and
"E" (Driver Side) and "C" and "F" (Passenger Side).
A copy of the emergency response guidelines (see Attachment "G") is enclosed with the
replacement SIR module and must be attached to the shipping papers you complete for the SIR
module being shipped.
4. Transportation
All SIR modules are to be returned using United Parcel Service (UPS) which will require the sender
to pre-pay the freight charges. If difficulties arise, contact Delphi Interior and Lighting Systems,
General Motors at (513) 356-2426.
5. RETURN ALL SUPPLEMENTAL INFLATABLE RESTRAINT MODULES (EXCEPT FOR THOSE
MODELS LISTED IN THIS BULLETIN) TO THE FOLLOWING ADDRESS:
Delphi Interior and Light Systems 3249 McCall Avenue Dayton, OH 45417
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8221
ATTACHMENT A DRIVER AIRBAG
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8222
ATTACHMENT B DRIVER SIDE
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8223
ATTACHMENT C DRIVER SIDE
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8224
ATTACHMENT D PASSENGER AIRBAG
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8225
ATTACHMENT E PASSENGER SIDE
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8226
ATTACHMENT F PASSENGER SIDE
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Technical
Service Bulletins > Air Bag - Module Shipping/Return Procedure > Page 8227
ATTACHMENT G
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Locations >
Component Locations
Air Bag: Component Locations
RH I/P
Steering Wheel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Locations >
Component Locations > Page 8230
RH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Locations >
Page 8231
Air Bag: Description and Operation
DESCRIPTION
The inflator modules consist of an inflatable bag and an inflator (a canister of gas-generating
material and an initiating device).
OPERATION
When the vehicle is in a frontal crash of sufficient force, the SDM or arming sensor causes current
to flow through the deployment loops. Current passing through the initiator ignites the material in
the inflator module. The gas produced from this reaction rapidly inflates the air bag.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Service and
Repair > Driver's Inflator Module
Air Bag: Service and Repair Driver's Inflator Module
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Remove module
attaching bolts from rear of steering wheel. 3. Rotate horn lead 1/4 turn and disconnect. 4.
Disconnect inflator module electrical connector, then remove module from steering wheel. 5.
Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition switch to On position and verify that the Air Bag or SIR warning lamp flashes seven
to nine times and then turns off. If lamp
does not respond as specified, refer to System Diagnosis
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag > Component Information > Service and
Repair > Driver's Inflator Module > Page 8234
Air Bag: Service and Repair Passenger's Inflator Module
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Remove instrument
panel upper trim pad. 3. Remove Connector Position Assurance (CPA), then disconnect module
electrical connector. 4. Remove inflator module attaching bolts, then the inflator module from
vehicle. 5. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition switch to On position and verify that the AIR BAG or SIR warning lamp flashes
seven to nine times and then turns off. If lamp
does not respond as specified, refer to System Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag Control Module > Component Information >
Locations > System Component Locations
Description
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag Control Module > Component Information >
Locations > System Component Locations > Page 8239
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag Control Module > Component Information >
Locations > Page 8240
Inflatable Restraint Diagnostic Energy Reserve (With Sensor) Module (SDM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Air Bag Control Module > Component Information >
Locations > Page 8241
Air Bag Control Module: Description and Operation
DESCRIPTION
The Sensing and Diagnostic Module (SDM) performs several system functions. These functions
include energy reserve, air bag deployment, malfunction detection, malfunction diagnosis, driver
notification, frontal crash detection and frontal crash recording.
OPERATION
The SDM contains a sensing device which converts vehicle velocity changes to an electrical signal.
The electrical signal generated is processed by the SDM and then compared to a value stored in
memory. When the generated signal exceeds the stored value, additional signals are compared to
signals stored in memory. When two of the generated signals exceed the stored values or when
one of the generated signals exceeds the stored value and the forward discriminating sensor
closes, the SDM will cause current to flow through the inflator modules deploying the air bags.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Clockspring Assembly / Spiral Cable, Air Bag >
Component Information > Locations > Component Locations
Steering Wheel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Clockspring Assembly / Spiral Cable, Air Bag >
Component Information > Locations > Component Locations > Page 8246
Clockspring Assembly / Spiral Cable: Connector Locations
Lower LH Side Of Steering Column
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Clockspring Assembly / Spiral Cable, Air Bag >
Component Information > Locations > Component Locations > Page 8247
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Clockspring Assembly / Spiral Cable, Air Bag >
Component Information > Locations > Page 8248
Clockspring Assembly / Spiral Cable: Description and Operation
DESCRIPTION
The SIR coil assembly consists of two current carrying coils. They are attached to the steering
column and allow rotation of the steering wheel while maintaining continuous contact of the driver
deployment loop to the driver's inflator module.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Clockspring Assembly / Spiral Cable, Air Bag >
Component Information > Locations > Page 8249
Clockspring Assembly / Spiral Cable: Service and Repair
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Position front wheels in
the straight ahead position. 3. Remove driver's air bag as described in Air Bag Module. 4.
Disconnect electrical connectors. 5. Place alignment marks on steering wheel hub and steering
column shaft for installation reference. 6. Remove steering wheel retaining nut. 7. Using suitable
steering wheel puller, remove steering wheel. 8. Place ignition switch in the Lock position, to retain
coil assembly in the centered position. 9. Remove coil assembly retaining ring.
10. Remove lock plate, turn signal canceling cam and upper bearing spring, inner race seat and
inner race. 11. Place turn signal lever in righthand turn position, then remove multi-function lever
and hazard flasher warning knob. 12. Remove turn signal switch lever attaching screw, then the
lever. 13. Remove turn signal switch attaching screws and allow switch to hang from wire. 14.
Disconnect SIR coil connector from turn signal switch electrical connector. 15. Using mechanics
wire, gently pull SIR coil wire through steering column. 16. Remove SIR coil assembly from
steering column. 17. Reverse procedure to install, noting the following:
a. Ensure wheels are in the straight ahead position. b. Ensure coil assembly is in the centered
position. c. After completing installation, rearm system as described in Air Bag System Disarming &
Arming. d. Turn ignition switch to On position and verify that the AIR BAG or SIR warning lamp
flashes seven to nine times and then turns off. If lamp
does not respond as specified, refer to System Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Discriminating Sensors and Arming Sensors <-->
[Impact Sensor] > Component Information > Locations
LH Radiator Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Discriminating Sensors and Arming Sensors <-->
[Impact Sensor] > Component Information > Locations > Page 8253
Discriminating Sensors and Arming Sensors: Description and Operation
DESCRIPTION
The discriminating and arming sensors are used by the SIR system to determine whether or not
certain frontal crashes require deployment of the air bags.
OPERATION
The sensor consists of a sensing element, normally open switch contacts and a diagnostic resistor.
The sensing element closes the switch contacts when the vehicle velocity changes are severe
enough to warrant air bag deployment.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Discriminating Sensors and Arming Sensors <-->
[Impact Sensor] > Component Information > Locations > Page 8254
Discriminating Sensors and Arming Sensors: Service and Repair
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
LEFT SENSOR
1. Disarm system as described in Air Bag System Disarming & Arming 2. Remove Connector
Position Assurance (CPA), then disconnect sensor electrical connector. 3. Remove sensor
mounting bolts, then the sensor. 4. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition key to the On position and verify the AIR BAG or SIR warning lamp flashes seven to
nine times, then turns off. If warning lamp
does not operate as specified, refer to Testing & Inspection.
RIGHT SENSOR
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Remove battery, then the
Connector Position Assurance (CPA). 3. Disconnect sensor electrical connector. 4. Remove sensor
mounting bolts, then the sensor. 5. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition key to the On position and verify the AIR BAG or SIR warning lamp flashes seven to
nine times, then turns off. If warning lamp
does not operate as specified, refer to System Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Seat Occupant Sensor > Component Information >
Technical Service Bulletins > Restraints - Passenger Presence System Information
Seat Occupant Sensor: Technical Service Bulletins Restraints - Passenger Presence System
Information
INFORMATION
Bulletin No.: 06-08-50-009F
Date: December 23, 2010
Subject: Information on Passenger Presence Sensing System (PPS or PSS) Concerns With
Custom Upholstery, Accessory Seat Heaters or Other Comfort Enhancing Devices
Models:
2011 and Prior GM Passenger Cars and Trucks Equipped with Passenger Presence Sensing
System
Supercede: This bulletin is being revised to update the model years. Please discard Corporate
Bulletin Number 06-08-50-009E (Section 08 - Body and Accessories).
Concerns About Safety and Alterations to the Front Passenger Seat
Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE THE
SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT AS RELEASED BY GM FOR THAT
VEHICLE. DO NOT ALTER THE SEAT COVERS OR SEAT-RELATED EQUIPMENT. ANY
ALTERATIONS TO SEAT COVERS OR GM ACCESSORIES DEFEATS THE INTENDED DESIGN
OF THE SYSTEM. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF
SUCH IMPROPER SEAT ALTERATIONS, INCLUDING ANY WARRANTY REPAIRS INCURRED.
The front passenger seat in many GM vehicles is equipped with a passenger sensing system that
will turn off the right front passenger's frontal airbag under certain conditions, such as when an
infant or child seat is present. In some vehicles, the passenger sensing system will also turn off the
right front passenger's seat mounted side impact airbag. For the system to function properly,
sensors are used in the seat to detect the presence of a properly-seated occupant. The passenger
sensing system may not operate properly if the original seat trim is replaced (1) by non-GM covers,
upholstery or trim, or (2) by GM covers, upholstery or trim designed for a different vehicle or (3) by
GM covers, upholstery or trim that has been altered by a trim shop, or (4) if any object, such as an
aftermarket seat heater or a comfort enhancing pad or device is installed under the seat fabric or
between the occupant and the seat fabric.
Aftermarket Seat Heaters, Custom Upholstery, and Comfort Enhancing Pads or Devices
Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE ONLY
SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT RELEASED AS GM
ACCESSORIES FOR THAT VEHICLE. DO NOT USE ANY OTHER TYPE OF SEAT COVERS OR
SEAT-RELATED EQUIPMENT, OR GM ACCESSORIES RELEASED FOR OTHER VEHICLE
APPLICATIONS. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF SUCH
IMPROPER SEAT ACCESSORIES, INCLUDING ANY WARRANTY REPAIRS MADE
NECESSARY BY SUCH USE.
Many types of aftermarket accessories are available to customers, upfitting shops, and dealers.
Some of these devices sit on top of, or are Velcro(R) strapped to the seat while others such as seat
heaters are installed under the seat fabric. Additionally, seat covers made of leather or other
materials may have different padding thickness installed that could prevent the Passenger Sensing
System from functioning properly. Never alter the vehicle seats. Never add pads or other devices to
the seat cushion, as this may interfere with the operation of the Passenger Sensing System and
either prevent proper deployment of the passenger airbag or prevent proper suppression of the
passenger air bag.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Diagnostic Energy Reserve Module (DERM) <-->
[Standby Power Supply, Air Bag] > Component Information > Description and Operation
Standby Power Supply: Description and Operation
DESCRIPTION
The Diagnostic Energy Reserve Module (DERM) performs several system functions. These
functions include energy reserve, malfunction detection, malfunction recording, driver notification
and frontal crash recording.
OPERATION
The DERM is connected to the SIR wiring harness by a 24-way connector. This harness connector
uses a shorting bar across certain terminals in the contact area. This shorting bar connects the AIR
BAG warning lamp to ground when the DERM harness connector is disconnected. This will cause
the AIR BAG warning lamp to come on steady whenever the ignition switch is at the Run, Bulb Test
or Start positions with the DERM disconnected.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Malfunction Lamp / Indicator, Air Bag > Component
Information > Technical Service Bulletins > Customer Interest for Malfunction Lamp / Indicator: > 83-81-34 > Mar > 99 > SIR
- Operating Vehicle with Warning Light On
Malfunction Lamp / Indicator: Customer Interest SIR - Operating Vehicle with Warning Light On
File In Section: 8 - Chassis/Body Electrical
Bulletin No.: 83-81-34
Date: March, 1999
INFORMATION
Subject: Operating Vehicle with Supplemental Inflatable Restraint (SIR) Warning Light Illuminated
Models: 1999 and Prior Passenger Cars and Light Duty Trucks with SDM Controlled Air Bag
System
The AIR BAG warning light is the key to driver notification of Supplemental Inflatable Restraint
(SIR) system malfunctions. When the warning light remains illuminated or continues to flash, one or
more of the following conditions may occur if vehicle operation is continued.
^ Non-deployment of the air bags in the event of a crash.
^ Deployment of the air bags without a crash.
^ Deployment of the air bags in crashes less severe than intended.
If an AIR BAG warning light is illuminated or flashing, you should advise the customer of these
possibilities and that the vehicle should be serviced right away.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Air Bag Systems > Malfunction Lamp / Indicator, Air Bag > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Malfunction Lamp / Indicator: > 83-81-34 >
Mar > 99 > SIR - Operating Vehicle with Warning Light On
Malfunction Lamp / Indicator: All Technical Service Bulletins SIR - Operating Vehicle with Warning
Light On
File In Section: 8 - Chassis/Body Electrical
Bulletin No.: 83-81-34
Date: March, 1999
INFORMATION
Subject: Operating Vehicle with Supplemental Inflatable Restraint (SIR) Warning Light Illuminated
Models: 1999 and Prior Passenger Cars and Light Duty Trucks with SDM Controlled Air Bag
System
The AIR BAG warning light is the key to driver notification of Supplemental Inflatable Restraint
(SIR) system malfunctions. When the warning light remains illuminated or continues to flash, one or
more of the following conditions may occur if vehicle operation is continued.
^ Non-deployment of the air bags in the event of a crash.
^ Deployment of the air bags without a crash.
^ Deployment of the air bags in crashes less severe than intended.
If an AIR BAG warning light is illuminated or flashing, you should advise the customer of these
possibilities and that the vehicle should be serviced right away.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Head Restraint System > System Information > Technical Service
Bulletins > Restraints - Driver/Passenger Seat Head Rest Information
Head Restraint System: Technical Service Bulletins Restraints - Driver/Passenger Seat Head Rest
Information
INFORMATION
Bulletin No.: 10-08-50-003A
Date: March 24, 2011
Subject: Information on Driver or Passenger Seat Head Restraint Concerns with Comfort, Custom
Upholstery or Other Comfort Enhancing Devices
Models:
2012 and Prior GM Passenger Cars and Trucks Equipped with Adjustable Head Restraints
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 10-08-50-003 (Section 08 - Body and Accessories).
Important ON A GM VEHICLE EQUIPPED WITH ADJUSTABLE HEAD RESTRAINTS, USE THE
HEAD RESTRAINT COVERS, FOAM AND OTHER SEAT-RELATED EQUIPMENT AS
RELEASED BY GM FOR THAT VEHICLE. DO NOT ALTER OR REPOSITION THE HEAD
RESTRAINT SYSTEM. ANY ALTERATIONS TO HEAD RESTRAINTS DEFEATS THE INTENDED
DESIGN OF THE SYSTEM. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE
OF SUCH IMPROPER DESIGN ALTERATIONS, INCLUDING ANY WARRANTY REPAIRS
INCURRED.
You may have a customer with a concern that the head restraint is uncomfortable or sits too far
forward. The front driver and passenger seats are equipped with head restraints that have been
designed to help minimize injuries while still providing comfort to the occupants. Each GM vehicle
has its own specifically designed head restraint.
The head restraints should only be used in the vehicle for which they were designed. The head
restraint will not operate to its design intent if the original foam is replaced (1) by non-GM foam or
head restraint, (2) by GM foam or head restraint designed for a different vehicle, (3) by GM foam or
head restraint that has been altered by a trim shop or (4) if any object, such as an aftermarket
comfort enhancing pad or device, is installed.
Never modify the design of the head restraint or remove the head restraint from the vehicle as this
may interfere with the operation of the seating and restraint systems and may prevent proper
positioning of the passenger within the vehicle.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Knee Diverter > Component Information > Service and Repair
Knee Diverter: Service and Repair
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Remove lower steering
column trim panel. 3. Remove four bolster mounting bolts, then the bolster from instrument panel.
4. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition switch to On position and verify that the AIR BAG or SIR warning lamp flashes
seven to nine times and then turns off. If lamp
does not respond as specified, refer to System Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > System Component Locations
Description
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > System Component Locations > Page 8287
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > Page 8288
Inflatable Restraint Diagnostic Energy Reserve (With Sensor) Module (SDM)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Relays and Modules - Restraint Systems > Air Bag Control Module >
Component Information > Locations > Page 8289
Air Bag Control Module: Description and Operation
DESCRIPTION
The Sensing and Diagnostic Module (SDM) performs several system functions. These functions
include energy reserve, air bag deployment, malfunction detection, malfunction diagnosis, driver
notification, frontal crash detection and frontal crash recording.
OPERATION
The SDM contains a sensing device which converts vehicle velocity changes to an electrical signal.
The electrical signal generated is processed by the SDM and then compared to a value stored in
memory. When the generated signal exceeds the stored value, additional signals are compared to
signals stored in memory. When two of the generated signals exceed the stored values or when
one of the generated signals exceeds the stored value and the forward discriminating sensor
closes, the SDM will cause current to flow through the inflator modules deploying the air bags.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Air Bag(s) Arming and Disarming > System
Information > Service and Repair > Air Bag Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Air Bag(s) Arming and Disarming > System
Information > Service and Repair > Air Bag Disarming and Arming > Page 8295
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Child Restraint > Child Seat Tether Attachment >
Component Information > Technical Service Bulletins > Restraints - Child Seat Top Teather Attachment Kits
Child Seat Tether Attachment: Technical Service Bulletins Restraints - Child Seat Top Teather
Attachment Kits
Bulletin No.: 99-09-40-004a
Date: April 12, 2005
INFORMATION
Subject: Top Tether Hardware Package for Child Restraint Seats
Models: 1989-2002 Passenger Cars, Light Duty Trucks and Multi-Purpose Passenger Vehicles
(Except EV1 and Prizm)
Supercede:
This bulletin is being revised to add the 2000-2002 model years. Please discard Corporate Bulletin
Number 99-09-40-009 (Section 09 - Restraints).
Important:
GM of Canada and IPC Dealers are not authorized to utilize this service bulletin.
Beginning in August, 1997 General Motors began providing Child Restraint Seat Top Tether
Hardware Packages to customers in the United States who requested them. The Top Tether
Hardware Package contains the necessary hardware for anchoring a forward facing child restraint
seat top tether.
One Child Restraint Seat Top Tether Hardware Package will be provided per vehicle to the retail
customer at no charge for installation. Charges for installation of additional Top Tether Hardware
Packages per vehicle are the responsibility of the customer.
Most forward facing child restraint seats (CRS) sold in the United States prior to calendar year
1999 were not sold with top tether straps, but have provisions for them. Top tethers, which are
required in Canada, can help to better secure the seat in the vehicle. When a forward facing CRS
including a top tether is used, specially designed components must be used to secure the child
seat top tether. These components are included in the Hardware Package from GMSPO.
Top tethers are not normally required or used with rearward facing infant restraint seats. Rearward
facing infant restraint seats should never be secured in the front seat of an air bag equipped
vehicle unless the vehicle is equipped with an air bag de-activation (shut-off) switch and the switch
has been used to turn the air bag off.
Should a retail customer request installation of a Tether Hardware Package at the time of sale or
delivery, it is to be installed at no charge to the owner. The labor to install a Tether Hardware
Package prior to delivery of a new vehicle to the customer is considered to be part of the delivery
"get ready process", and as such, is not claimable. Claiming for the cost and applicable handling
allowance of the proper Tether Hardware Package used in the installation is allowed.
If the customer requests installation of a Tether Hardware Package some time after delivery, the
package is to be provided free of charge. Hardware Packages include installation instructions
which are easily followed and can be installed by most customers. However, should the customer
request the dealership's assistance to install the Tether Hardware Package, it is to be installed at
no charge to the customer and the labor may be claimed. All claims submitted for installation labor
of an approved Tether Hardware Package must be supported by a signed customer work order.
Additional Hardware Packages and installation charges are the responsibility of the customer.
In addition, passenger vehicle deliveries, including vans and sport utilities for daily rental usage,
may have one tether hardware package supplied. Additional packages are the owner's
responsibility. Dealers may claim appropriate parts under these circumstances. Sufficient quantities
of parts should be ordered in advance of the arrival of vehicles to avoid delays.
Important:
When installing a Child Restraint Seat Top Tether Hardware Package, follow the installation
instructions included in the package. Additional information about specific mounting locations and
installations may be available in the Seat Belt Section (Sections 9, 10-10, 10-11 or 10A) I of the
appropriate Service Manual, or the Restraints section of SI.
Any questions regarding this policy should be directed to your Area Manager, Parts or Service.
Parts Information
For Top Tether Hardware Package part numbers and usage, see Group 14.870 (passenger cars &
U-van), or Group 16.710 (Light Duty Truck) of the appropriate GMSPO Parts Catalog. In addition,
they can also be found in Accessories Group 21.042.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Child Restraint > Child Seat Tether Attachment >
Component Information > Technical Service Bulletins > Restraints - Child Seat Top Teather Attachment Kits > Page 8301
Warranty Information
The dealership will be reimbursed for the parts and labor, if applicable, through the submission of a
regular warranty claim.
All claims submitted must be supported by a signed customer work order. Purchase and installation
of additional Hardware Packages is the responsibility of the customer.
For Top Tether Hardware Packages installed in the United States, submit as a normal warranty
claim using the labor operations and time allowances shown.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle > Component Information >
Technical Service Bulletins > Customer Interest for Seat Belt Buckle: > 09-09-40-001A > Feb > 11 > Restraints - Seat Belt
Warning Lamp On/Buckling Issues
Seat Belt Buckle: Customer Interest Restraints - Seat Belt Warning Lamp On/Buckling Issues
INFORMATION
Bulletin No.: 09-09-40-001A
Date: February 02, 2011
Subject: Seat Belt Buckle Latching Issues and/or Seat Belt Warning Lights Illuminated
Models:
2011 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7 X
Supercede: This bulletin is being revised to add the 2011 model year. Please discard Corporate
Bulletin Number 09-09-40-001 (Section 09 - Restraints).
This bulletin is being published to advise dealers about seat belt buckles not operating and/or seat
belt warning light illumination, as well as difficulty latching and unlatching the buckle or the buckle
release button sticking.
Analysis of warranty data has determined that this condition may be caused by sticky beverages
being spilled onto or into the seat belt buckle assembly. Foreign debris from food, candy wrappers,
paper and coins can also contribute to this condition.
Important If foreign material (debris) or sticky liquids are the cause of the concern, show the
customer the condition of the component (buckle assembly) and explain how it is affecting the
function of the restraint system. Strongly recommend that the component be replaced. Point out the
fact that this is not a manufacturing defect and is not covered by the new vehicle warranty. If the
customer declines to have parts replaced, the service department management must make a
notation on the service record that the lack of functionality of seating position with an inoperative
buckle was fully explained to the customer. The service department management must advise the
customer that having a non-functioning buckle in a seating position voids ability to use that seating
position (no one should ride in the seat). Also make the customer aware that it may be against the
law to ride in a vehicle without wearing a restraint system.
Important Never insert anything other than the seat belt latch plate into the buckle assembly. Do
not attempt to dig anything out of a buckle with a tool. Never try to wash out a buckle to remove a
spilled liquid as this may damage the buckle.
Use the following steps to determine the cause of the concern.
1. Inspect the buckle assembly with a light shining on the latch plate insertion area. Look for any
debris or foreign objects in the buckle. 2. If any debris or foreign objects are observed, try to
vacuum out the item. After the foreign material is removed, latch and unlatch the seat belt. If
the system functions properly, do not replace the seat belt buckle assembly.
3. If the condition has not been corrected, inspect the buckle assembly for any sticky residue. If
sticky residue is found, inform the customer that a
substance was spilled on the seat belt buckle assembly causing the malfunction. The buckle
assembly will need to be replaced at the customer's expense.
4. Refer to SI for seat belt component replacement.
Important If foreign material (debris) or sticky liquids are the cause of the concern, show the
customer the condition of the component (buckle assembly) and explain how it is affecting the
function of the restraint system. Strongly recommend that the component be replaced at the
customer's expense. Point out the fact that this is not a manufacturing defect and is not covered by
the new vehicle warranty. If the customer declines to have parts replaced, the service department
management must make a notation on the service record that the lack of functionality of seating
position with an inoperative buckle was fully explained to the customer. The service department
management must advise customer that having a non-functioning buckle in a seating position voids
ability to use that seating position (no one should ride in the seat). Also make the customer aware
that it may be against the law to ride in a vehicle without wearing a restraint system.
5. If further restraint diagnosis is required, refer to Seat Belt System Operational and Functional
Checks in SI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle > Component Information >
Technical Service Bulletins > Customer Interest for Seat Belt Buckle: > 09-09-40-001A > Feb > 11 > Restraints - Seat Belt
Warning Lamp On/Buckling Issues > Page 8310
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Seat Belt Buckle: > 09-09-40-001A > Feb > 11 > Restraints
- Seat Belt Warning Lamp On/Buckling Issues
Seat Belt Buckle: All Technical Service Bulletins Restraints - Seat Belt Warning Lamp On/Buckling
Issues
INFORMATION
Bulletin No.: 09-09-40-001A
Date: February 02, 2011
Subject: Seat Belt Buckle Latching Issues and/or Seat Belt Warning Lights Illuminated
Models:
2011 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7 X
Supercede: This bulletin is being revised to add the 2011 model year. Please discard Corporate
Bulletin Number 09-09-40-001 (Section 09 - Restraints).
This bulletin is being published to advise dealers about seat belt buckles not operating and/or seat
belt warning light illumination, as well as difficulty latching and unlatching the buckle or the buckle
release button sticking.
Analysis of warranty data has determined that this condition may be caused by sticky beverages
being spilled onto or into the seat belt buckle assembly. Foreign debris from food, candy wrappers,
paper and coins can also contribute to this condition.
Important If foreign material (debris) or sticky liquids are the cause of the concern, show the
customer the condition of the component (buckle assembly) and explain how it is affecting the
function of the restraint system. Strongly recommend that the component be replaced. Point out the
fact that this is not a manufacturing defect and is not covered by the new vehicle warranty. If the
customer declines to have parts replaced, the service department management must make a
notation on the service record that the lack of functionality of seating position with an inoperative
buckle was fully explained to the customer. The service department management must advise the
customer that having a non-functioning buckle in a seating position voids ability to use that seating
position (no one should ride in the seat). Also make the customer aware that it may be against the
law to ride in a vehicle without wearing a restraint system.
Important Never insert anything other than the seat belt latch plate into the buckle assembly. Do
not attempt to dig anything out of a buckle with a tool. Never try to wash out a buckle to remove a
spilled liquid as this may damage the buckle.
Use the following steps to determine the cause of the concern.
1. Inspect the buckle assembly with a light shining on the latch plate insertion area. Look for any
debris or foreign objects in the buckle. 2. If any debris or foreign objects are observed, try to
vacuum out the item. After the foreign material is removed, latch and unlatch the seat belt. If
the system functions properly, do not replace the seat belt buckle assembly.
3. If the condition has not been corrected, inspect the buckle assembly for any sticky residue. If
sticky residue is found, inform the customer that a
substance was spilled on the seat belt buckle assembly causing the malfunction. The buckle
assembly will need to be replaced at the customer's expense.
4. Refer to SI for seat belt component replacement.
Important If foreign material (debris) or sticky liquids are the cause of the concern, show the
customer the condition of the component (buckle assembly) and explain how it is affecting the
function of the restraint system. Strongly recommend that the component be replaced at the
customer's expense. Point out the fact that this is not a manufacturing defect and is not covered by
the new vehicle warranty. If the customer declines to have parts replaced, the service department
management must make a notation on the service record that the lack of functionality of seating
position with an inoperative buckle was fully explained to the customer. The service department
management must advise customer that having a non-functioning buckle in a seating position voids
ability to use that seating position (no one should ride in the seat). Also make the customer aware
that it may be against the law to ride in a vehicle without wearing a restraint system.
5. If further restraint diagnosis is required, refer to Seat Belt System Operational and Functional
Checks in SI.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Seat Belt Buckle: > 09-09-40-001A > Feb > 11 > Restraints
- Seat Belt Warning Lamp On/Buckling Issues > Page 8316
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle Switch > Component
Information > Locations > Component Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle Switch > Component
Information > Locations > Component Locations > Page 8321
Seat Belt Buckle Switch: Connector Locations
Cross Car Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Buckle Switch > Component
Information > Locations > Component Locations > Page 8322
Cross Car Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Seat Belt Systems > Seat Belt Extension > Component Information >
Technical Service Bulletins > Restraints - Extender Availability For Seat Belt
Seat Belt Extension: Technical Service Bulletins Restraints - Extender Availability For Seat Belt
INFORMATION
Bulletin No.: 99-09-40-005F
Date: June 23, 2010
Subject: Seat Belt Extender Availability
Models: 2011 and Prior GM Passenger Cars and Trucks (Including Saturn) 2009 and Prior
HUMMER H2 2010 and Prior HUMMER H3 2005-2009 Saab 9-7X
Supercede:
This bulletin is being revised to add the 2009‐2011 model years and update the Warranty
Information. Please discard Corporate Bulletin Number 99-09-40-005E (Section 09 Restraints).
Important:
DO NOT use belt extenders when securing a child restraint.
The seat and shoulder belt restraint systems used in all General Motors vehicles have sufficient
belt length to accommodate most drivers and passengers. Consequently, requests for belt
extensions (extenders) should be minimal.
Seat belt extenders are available ONLY IN BLACK for most GM passenger cars and trucks
produced in recent years. They are available in two different lengths, 23 cm (9 in) and 38 cm (15
in). They are designed to be coupled with the existing belts in each vehicle. When in use, the
extender makes the belt arrangement a "custom fit" and use by anyone else or in another vehicle
will lessen or nullify the protection offered by the vehicle's restraint system. For this reason, it is
extremely important that the correct length extender be used for the vehicle and occupant intended.
Important:
Do not use an extender just to make it easier to buckle the safety belt. Use an extender only when
you cannot buckle the safety belt without using an extender.
Parts Information
For part numbers, usage and availability of extenders, see Extension Kit in Group 14.875 (cars) or
Group 16.714 (trucks) of the appropriate parts catalog. Saturn retailers should refer to the
appropriate model year Parts & Illustration catalog for the vehicle. U.S. Saab dealers should contact
the Parts Help line. Canadian Saab dealers should fax requests to Partech Canada.
Warranty Information
^ Seat belt extenders are a NO CHARGE item to all GM customers who request them for their
specific vehicles.
^ Dealers should not be charging part costs since these extenders are supplied by GM to the
dealers.
^ Dealers should not be charging labor costs since the extender can be customer installed.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Discriminating Sensors
and Arming Sensors <--> [Impact Sensor] > Component Information > Locations
LH Radiator Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Discriminating Sensors
and Arming Sensors <--> [Impact Sensor] > Component Information > Locations > Page 8331
Discriminating Sensors and Arming Sensors: Description and Operation
DESCRIPTION
The discriminating and arming sensors are used by the SIR system to determine whether or not
certain frontal crashes require deployment of the air bags.
OPERATION
The sensor consists of a sensing element, normally open switch contacts and a diagnostic resistor.
The sensing element closes the switch contacts when the vehicle velocity changes are severe
enough to warrant air bag deployment.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Discriminating Sensors
and Arming Sensors <--> [Impact Sensor] > Component Information > Locations > Page 8332
Discriminating Sensors and Arming Sensors: Service and Repair
WARNING: The diagnostic energy reserve module or sensing and diagnostic module
(DERM/SDM) can maintain enough voltage to cause air bag deployment for up to two minutes after
the ignition switch is turned off and the battery is disconnected. Servicing the SIR system during
this period may result in accidental deployment and personal injury.
LEFT SENSOR
1. Disarm system as described in Air Bag System Disarming & Arming 2. Remove Connector
Position Assurance (CPA), then disconnect sensor electrical connector. 3. Remove sensor
mounting bolts, then the sensor. 4. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition key to the On position and verify the AIR BAG or SIR warning lamp flashes seven to
nine times, then turns off. If warning lamp
does not operate as specified, refer to Testing & Inspection.
RIGHT SENSOR
1. Disarm system as described in Air Bag System Disarming & Arming. 2. Remove battery, then the
Connector Position Assurance (CPA). 3. Disconnect sensor electrical connector. 4. Remove sensor
mounting bolts, then the sensor. 5. Reverse procedure to install, noting the following:
a. After completing installation, rearm system as described in Air Bag System Disarming & Arming.
b. Turn ignition key to the On position and verify the AIR BAG or SIR warning lamp flashes seven to
nine times, then turns off. If warning lamp
does not operate as specified, refer to System Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Seat Belt Buckle Switch
> Component Information > Locations > Component Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Seat Belt Buckle Switch
> Component Information > Locations > Component Locations > Page 8337
Seat Belt Buckle Switch: Connector Locations
Cross Car Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Seat Belt Buckle Switch
> Component Information > Locations > Component Locations > Page 8338
Cross Car Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Restraint Systems > Sensors and Switches - Restraint Systems > Seat Occupant Sensor >
Component Information > Technical Service Bulletins > Restraints - Passenger Presence System Information
Seat Occupant Sensor: Technical Service Bulletins Restraints - Passenger Presence System
Information
INFORMATION
Bulletin No.: 06-08-50-009F
Date: December 23, 2010
Subject: Information on Passenger Presence Sensing System (PPS or PSS) Concerns With
Custom Upholstery, Accessory Seat Heaters or Other Comfort Enhancing Devices
Models:
2011 and Prior GM Passenger Cars and Trucks Equipped with Passenger Presence Sensing
System
Supercede: This bulletin is being revised to update the model years. Please discard Corporate
Bulletin Number 06-08-50-009E (Section 08 - Body and Accessories).
Concerns About Safety and Alterations to the Front Passenger Seat
Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE THE
SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT AS RELEASED BY GM FOR THAT
VEHICLE. DO NOT ALTER THE SEAT COVERS OR SEAT-RELATED EQUIPMENT. ANY
ALTERATIONS TO SEAT COVERS OR GM ACCESSORIES DEFEATS THE INTENDED DESIGN
OF THE SYSTEM. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF
SUCH IMPROPER SEAT ALTERATIONS, INCLUDING ANY WARRANTY REPAIRS INCURRED.
The front passenger seat in many GM vehicles is equipped with a passenger sensing system that
will turn off the right front passenger's frontal airbag under certain conditions, such as when an
infant or child seat is present. In some vehicles, the passenger sensing system will also turn off the
right front passenger's seat mounted side impact airbag. For the system to function properly,
sensors are used in the seat to detect the presence of a properly-seated occupant. The passenger
sensing system may not operate properly if the original seat trim is replaced (1) by non-GM covers,
upholstery or trim, or (2) by GM covers, upholstery or trim designed for a different vehicle or (3) by
GM covers, upholstery or trim that has been altered by a trim shop, or (4) if any object, such as an
aftermarket seat heater or a comfort enhancing pad or device is installed under the seat fabric or
between the occupant and the seat fabric.
Aftermarket Seat Heaters, Custom Upholstery, and Comfort Enhancing Pads or Devices
Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE ONLY
SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT RELEASED AS GM
ACCESSORIES FOR THAT VEHICLE. DO NOT USE ANY OTHER TYPE OF SEAT COVERS OR
SEAT-RELATED EQUIPMENT, OR GM ACCESSORIES RELEASED FOR OTHER VEHICLE
APPLICATIONS. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF SUCH
IMPROPER SEAT ACCESSORIES, INCLUDING ANY WARRANTY REPAIRS MADE
NECESSARY BY SUCH USE.
Many types of aftermarket accessories are available to customers, upfitting shops, and dealers.
Some of these devices sit on top of, or are Velcro(R) strapped to the seat while others such as seat
heaters are installed under the seat fabric. Additionally, seat covers made of leather or other
materials may have different padding thickness installed that could prevent the Passenger Sensing
System from functioning properly. Never alter the vehicle seats. Never add pads or other devices to
the seat cushion, as this may interfere with the operation of the Passenger Sensing System and
either prevent proper deployment of the passenger airbag or prevent proper suppression of the
passenger air bag.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antenna > Antenna Motor > Component Information
> Locations
RH Rear Side Of Engine Compartment With Radio Power Antenna
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antenna > Antenna Relay > Component Information
> Locations > Power Antenna Relay
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antenna > Antenna Relay > Component Information
> Locations > Power Antenna Relay > Page 8352
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antenna > Antenna, Radio > Component
Information > Locations
RH Rear Side Of Engine Compartment With Radio Power Antenna
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Alarm Module,
(Vehicle Antitheft) > Component Information > Service and Repair
Alarm Module: Service and Repair
PROGRAMMING A NEW THEFT DETERRENT MODULE
IMPORTANT: Any new PASS-Key II Theft Deterrent Module will automatically program to the
resistance of the key (or interrogator setting) being used at the first ignition "ON" cycle. This can
only be done once for the life of the module.
New modules are unprogrammed. Before the system will function properly after a new module has
been installed, it must be programmed to the code that matches the customer1s keys.
Programming a new module is very simple:
1. Install the new, unprogrammed module. 2. Insert one of the customer's keys in the ignition lock
cylinder and turn it to the "ON" position. It's a good idea to start the Engine at this time to
verify system operation.
3. Observe the "PASSKEY" indicator Lamp:
^ The indicator lamp should light for about five seconds and then go out. If the wiring or contacts to
the Key Resistance Pellet or the key is defective or intermittent and a new module is installed, the
Engine will start but the "PASSKEY" indicator will flash at a rate of one flash per second until the
Ignition Switch is turned off. This indicates that the module did not program and that the system
components, wiring and contacts should be checked for a fault.
IMPORTANT: Before connecting the interrogrator to the ignition lock cylinder circuit, always verify
vehicle key code and set the code into the interrogrator using the "key code" knob. This will prevent
programming an unprogrammed module with an undesired key code.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Antitheft Relay >
Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Antitheft Relay >
Component Information > Locations > Page 8363
Theft Deterrent Relay Daytime Running Lamps (DRL) Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Ignition Key In
Signal, Antitheft > Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Programming Connector > Component Information > Locations
Keyless Entry Programming Connector: Locations
LH Luggage Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Receiver > Component Information > Locations
Rear Shelf, Top View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Receiver > Component Information > Locations > Page 8374
Keyless Entry Receiver: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Receiver > Component Information > Locations > Page 8375
C406: Body Harness To Tailgate Harness, Headlamp Automatic Control Module (C1), Remote
Control Door Lock Receiver
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Transmitter > Component Information > Technical Service Bulletins > Tools Keyless Entry Transmitter Tester
Keyless Entry Transmitter: Technical Service Bulletins Tools - Keyless Entry Transmitter Tester
File In Section: 9 - Accessories
Bulletin No.: 83-90-12
Date: August, 1998
INFORMATION
Subject: Essential Tool J 43241 Remote Keyless Entry and Passive Keyless Entry Transmitter
Tester
Models:
1990-99 Passenger Cars and Trucks with Remote Keyless Entry or Passive Keyless Entry
Systems
A new essential tool, J 43241 Remote Keyless Entry Transmitter Tester, has been sent to all GM
Dealers. This tester can be used on all RKE and PKE systems, on past as well as current models.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Transmitter > Component Information > Technical Service Bulletins > Tools Keyless Entry Transmitter Tester > Page 8380
Important:
Before using the tester and the diagnostic chart, the following two steps must be performed.
1. Verify that the keyless entry transmitter is the correct model for the vehicle remote system. An
incorrect model transmitter may pass this test, but may not activate the vehicle remote system. The
correct transmitter can usually be identified by part number.
2. Ensure that the transmitter is synchronized with the vehicle (if applicable). Refer to Transmitter
Synchronization in the appropriate Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Remote Keyless
Entry <--> [Keyless Entry] > Keyless Entry Transmitter > Component Information > Technical Service Bulletins > Page 8381
Keyless Entry Transmitter: Service and Repair
1. Reposition rear compartment trim to access the programming connector located at the left of the
rear compartment, for sedan.
2. Remove right back body pillar finish panel to access programming connector, for wagon.
3. Ground the programming connector by connecting the terminals together.
^ The system will verify this has occurred by performing a lock all, unlock drivers door/unlock all,
and trunk/endgate cycle.
4. Press any key on either transmitter.
^ This step programs that particular transmitter to the receiver.
^ The system will verify by performing the same lock/unlock, lock/unlock cycle.
5. The Automatic Door Locking/Unlocking function is automatically enabled for this transmitter. To
leave it enabled, skip to step 6. To disable the
Automatic Door Locking/Unlocking function for this transmitter, perform the following sequence 3
times.
A. Press the door lock button within 1 second of step C the 2nd and 3rd time through this
sequence.
B. Press the door unlock button within 1 second of step A.
C Press the trunk button within 1 second of step B.
^ The receiver will cycle through the lock, unlock, trunk sequence 3 times as verification.
6. To program a second transmitter to the receiver, repeat step 4 with the second transmitter.
Otherwise, go to 7.
7. Disconnect the programming connector.
^ System will not operate if ground connection is not removed.
8. Verify operation of each transmitter.
9. Reposition rear compartment trim, for sedan.
10. Install right back body pillar finish panel, for wagon.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Antitheft and Alarm Systems > Security
Lamp/Indicator > Component Information > Description and Operation
Security Lamp/Indicator: Description and Operation
The security indicator is controlled by the theft deterrent module. The module will turn the
SECURITY lamp on for about five seconds during engine start-up for a bulb check. A solid (not
flashing) SECURITY indicator is illuminated if the theft deterrent module enters shut down mode
thus preventing the vehicle from starting.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting
Technical Service Bulletin # 83-96-05 Date: 980701
Radio Telephone/Mobile Radio - Install/Troubleshooting
File In Section: 9 - Accessories
Bulletin No.: 83-96-05
Date: July, 1998
Subject: Radio Telephone/Mobile Radio (Transceiver) Installation and Troubleshooting Guidelines
Models: 1990-99 Passenger Cars and Trucks
This bulletin cancels and supercedes bulletin 34-92-12. Please discard Corporate Bulletin Number
34-92-12 (Section 9 - Accessories).
The following information is being provided to assist in the installation and troubleshooting of Radio
Telephone/Mobile Radios.
Certain radio telephones or land mobile radios (also known as Radio Transceivers), or the way in
which they are installed, may adversely affect various vehicle operations such as engine
performance, driver information, entertainment and electrical systems.
Expenses incurred to protect the vehicle systems from any adverse effect of any such installation
are NOT the responsibility of General Motors Corporation.
The following are general guidelines for installing a radio transceiver in General Motors vehicles.
These guidelines are intended to supplement, but not to be used in place of, detailed instructions
which are the sole responsibility of the manufacturer of the involved radio transceiver. Although this
document refers to passenger vehicles, the same general guidelines apply to trucks.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting > Page 8389
EMC TROUBLESHOOTING CHART
1. Transceiver Location
Refer to the attached figures during installation.
1. Transceiver Location
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting > Page 8390
a. One piece transceivers should be mounted under the dash, or on the transmission hump where
they will not interfere with vehicle controls or passenger movement (See Figure 1 - One Piece
Transceiver Installation).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting > Page 8391
b. Locate the transceiver for remote radios on the driver's side of trunk as near to the vehicle body
side as possible (See Figure 2 - Trunk Mount Transceiver Installation).
Caution:
To avoid possible serious injury, do not mount any transceivers, microphones, speakers, or any
other item In the deployment path of a Supplemental Inflatable Restraint (SIR) or "Air Bag".
2. Antenna Installation
a. Each vehicle model reacts to radio frequency energy differently.
It is suggested that a magnetic-mount antenna be used to check the proposed antenna location for
unwanted effects on the vehicle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting > Page 8392
Antenna location is a major factor in these effects.
b. The antenna should be a permanent-mount type, located in the center of the roof or center of the
rear deck lid.
If a magnet-mount antenna is used, care should be taken to mount the antenna in the same
location as a permanent-mount type.
If a disguise-mount antenna is used, great care should be taken to shield (using copper tape, etc.)
any tuning network from vehicle electronics and wiring, or mount the tuning network in an area
completely clear (6 inches or 15 cm away) of vehicle electronics and wiring.
c. Standard metal mount antennas may be mounted on a vehicle with non-metallic body panels by
two methods:
1. Mount the antenna near a metal frame section and bond the antenna mount to the frame with a
short metal strap, which will provide the ground plane connection.
2. Some antenna manufacturers may offer "Ground Plane Kits" that consist of self adhesive metal
foil that may be attached to the body panel to provide a ground plane connection.
d. Glass Mount Antennas
Glass mounted antennas should be kept as high as possible in the center of the rear window or
windshield, between rear window defrost "grid lines", if present.
Some vehicles use glass that contains a thin metallic layer for defrosting, or to control solar gain.
GLASS MOUNT ANTENNAS WILL NOT FUNCTION WHEN MOUNTED ON THIS TYPE OF
GLASS.
3. Antenna Cable Routing
a. Always use high quality coax cable (95% shield coverage minimum), located away (at least 6
inches or 15 cm) from ECM's, PCM's and other electronic modules.
b. Care should be taken to maintain as great a distance as possible between any vehicle wiring
and coax cable.
4. Antenna Tuning
It is important that the antenna be tuned properly and that reflected power be kept to less than 10%
(VSWR less than 2:1) at all operating frequencies.
Important:
High VSWR has been shown to contribute/cause interference problems with vehicle systems.
5. Radio Wiring and Power Lead Connection Locations
a. Methods to connect radio power on General Motors vehicles is dependent on the vehicle model
(See Figure 1 - One Piece Transceiver Installation or Figure 2 - Trunk Mount Transceiver
Installation as needed).
Do not connect the negative power lead to any under-dash termination point.
One of the following four methods is suggested:
1. Connect the positive and negative power leads directly to the battery terminals.
GM approved methods of connecting auxiliary wiring include the adapter package illustrated in
Figure 4 - Power Cable Battery Connections.
Important:
It is recommended that a fuse be placed in the transceiver negative power lead.
This is to prevent possible transceiver damage in the event the battery to engine block ground lead
is inadvertently disconnected.
2. Connect the positive lead to the auxiliary power terminal (usually identified by a red plastic cover
in the underhood area).
Connect the negative lead directly to the negative battery terminal.
Important:
See above important statement regarding fusing the negative power lead.
3. Connect the positive lead to the auxiliary power terminal (usually identified by a red plastic cover
in the underhood area).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting > Page 8393
Connect the negative lead to the battery body connection point (usually identified by a short # 10
AWG or larger wire running from the negative battery terminal to the body of the vehicle).
Important:
See above important statement regarding fusing the negative power lead.
4. Connect the positive and negative leads to the Special Equipment Option (SEO) wiring provided
for this purpose (if vehicle has this option).
b. For One Piece Transceivers (See Figure 1 - One Piece Transceiver Installation)
When ignition switch control is desired, and no SEO wiring exists, a 12 volt power contactor must
be installed in the transceiver positive power lead (See Figure 3 - Power Contactor Wiring).
The contactor (supplied by the installer) should be located near a proper 12 volt feed source.
One lead of the contactor coil should be connected through an appropriate in-line fuse to an
available accessory circuit or ignition circuit not
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Cellular Phone > Component Information >
Technical Service Bulletins > Radio Telephone/Mobile Radio - Install/Troubleshooting > Page 8394
powered during engine cranking.
The return lead of the contactor coil must return to a proper fused negative point.
c. Handset or Control Units
1. Any negative power lead from a handset or control unit must return to a properly fused negative
connection point.
2. It is preferable that the positive power lead for a handset, or control unit, be connected directly to
a properly fused positive power feed point.
If ignition switch control is desired, the handset or control unit positive power lead may be
connected through an appropriate in-line fuse to an available accessory circuit (or ignition circuit
not powered during engine cranking).
3. It is recommended that the handset or control unit positive and negative power leads be
appropriately fused separately from the transceiver positive and negative power leads.
d. Multiple Transceivers or Receivers
If multiple transceivers or receivers are to be installed in the vehicle, power leads to the trunk or
under the dash should be connected to covered, insulated terminal strips.
All transceivers or receivers may then have their power leads connected to the insulated terminal
strips. This makes a neater installation and reduces the number of wires running to the vehicle
underhood area.
Both positive and negative power leads should be fused.
6. Radio Wire Routing
(See Figure 1 - One Piece Transceiver Installation, or Figure 2 - Trunk Mount Transceiver
Installation as needed).
a. The power leads (fused) should be brought through a grommeted hole (provided by the installer)
in the front cowl.
For trunk mounted transceivers, the cables should continue on along the driver's side door sills,
under the rear seat and into the trunk through a rear bulkhead.
Maintain as great a distance as possible between radio power leads and vehicle electronic
modules and wiring.
b. If the radio power leads need to cross the engine compartment, they should cross between the
engine and the front of the vehicle.
Troubleshooting
Refer to the Troubleshooting Chart as needed.
1. Most vehicle-radio interaction is avoided by following the Installation Guidelines outlined above.
2. If vehicle-radio interaction is evident following radio installation, the source of the problem should
be determined prior to further vehicle/radio operation.
The EMC Troubleshooting Chart should help in determining the source of the vehicle-radio
interaction.
Parts Information
P/N Description
1846855 Adapter Kit, Side Terminal Battery (consisting of Adapter Terminal,
Terminal Cover, Wire Connector, Insulation Boot)
12004188 Bolt, Battery Cable Terminal
12354951 Spacer, Battery Cable Terminal
Parts are currently available from GMSPO.
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Locations > Cellular Mobile Telephone Microphone Connector (UV8)
Front Headliner
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Locations > Cellular Mobile Telephone Microphone Connector (UV8) > Page 8397
RH Lower Instrument Panel
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Locations > Cellular Mobile Telephone Microphone Connector (UV8) > Page 8398
RH Luggage Compartment (UV8)
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Diagrams > Diagram Information and Instructions
Cellular Phone: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Cellular Phone: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Cellular Phone: Electrical Diagrams
Cellular Mobile Telephone (Part 1 Of 2)
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Cellular Mobile Telephone (Part 2 Of 2)
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Chevrolet Workshop Manuals > Accessories and Optional Equipment > Emergency Contact Module > Component
Information > Technical Service Bulletins > OnStar(R) - Aftermarket Device Interference Information
Emergency Contact Module: Technical Service Bulletins OnStar(R) - Aftermarket Device
Interference Information
INFORMATION
Bulletin No.: 08-08-46-004
Date: August 14, 2008
Subject: Information on Aftermarket Device Interference with OnStar(R) Diagnostic Services
Models: 2009 and Prior GM Passenger Car and Truck (including Saturn) 2009 and Prior HUMMER
H2, H3 Models 2009 and Prior Saab 9-7X
with OnStar(R) (RPO UE1)
This bulletin is being issued to provide dealer service personnel with information regarding
aftermarket devices connected to the Diagnostic Link Connector (DLC) and the impact to
OnStar(R) diagnostic probes and Vehicle Diagnostic e-mails.
Certain aftermarket devices, when connected to the Diagnostic Link Connector, such as, but not
limited to, Scan Tools, Trip Computers, Fuel Economy Analyzers and Insurance Tracking Devices,
interfere with OnStar's ability to perform a diagnostic probe when requested (via a blue button call)
by a subscriber. These devices also prohibit the ability to gather diagnostic and tire pressure data
for a subscriber's scheduled OnStar(R) Vehicle Diagnostic (OVD) e-mail.
These aftermarket devices utilize the Vehicles serial data bus to perform data requests and/or
information gathering. When these devices are requesting data, OnStar(R) is designed not to
interfere with any data request being made by these devices as required by OBD II regulations.
The OnStar(R) advisor is unable to definitively detect the presence of these devices and will only
be able to inform the caller or requester of the unsuccessful or incomplete probe and may in some
cases refer the subscriber/requester to take the vehicle to a dealer for diagnosis of the concern.
When performing a diagnostic check for an unsuccessful or incomplete OnStar(R) diagnostic
probe, or for concerns regarding completeness of the OnStar(R) Vehicle Diagnostic (OVD) e-mail,
verify that an aftermarket device was not present at the time of the requested probe. Regarding the
OVD e-mail, if an aftermarket device is interfering (including a Scan Tool of any type), the e-mail
will consistently display a "yellow" indication in diagnostics section for all vehicle systems except
the OnStar(R) System and Tire Pressure data (not available on all vehicles) will not be displayed
(i.e. section is collapsed). Successful diagnostic probes and complete OVD e-mails will resume
following the removal or disconnecting of the off-board device.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Global Positioning System > Component
Information > Technical Service Bulletins > OnStar(R) - Aftermarket Device Interference Information
Global Positioning System: Technical Service Bulletins OnStar(R) - Aftermarket Device
Interference Information
INFORMATION
Bulletin No.: 08-08-46-004
Date: August 14, 2008
Subject: Information on Aftermarket Device Interference with OnStar(R) Diagnostic Services
Models: 2009 and Prior GM Passenger Car and Truck (including Saturn) 2009 and Prior HUMMER
H2, H3 Models 2009 and Prior Saab 9-7X
with OnStar(R) (RPO UE1)
This bulletin is being issued to provide dealer service personnel with information regarding
aftermarket devices connected to the Diagnostic Link Connector (DLC) and the impact to
OnStar(R) diagnostic probes and Vehicle Diagnostic e-mails.
Certain aftermarket devices, when connected to the Diagnostic Link Connector, such as, but not
limited to, Scan Tools, Trip Computers, Fuel Economy Analyzers and Insurance Tracking Devices,
interfere with OnStar's ability to perform a diagnostic probe when requested (via a blue button call)
by a subscriber. These devices also prohibit the ability to gather diagnostic and tire pressure data
for a subscriber's scheduled OnStar(R) Vehicle Diagnostic (OVD) e-mail.
These aftermarket devices utilize the Vehicles serial data bus to perform data requests and/or
information gathering. When these devices are requesting data, OnStar(R) is designed not to
interfere with any data request being made by these devices as required by OBD II regulations.
The OnStar(R) advisor is unable to definitively detect the presence of these devices and will only
be able to inform the caller or requester of the unsuccessful or incomplete probe and may in some
cases refer the subscriber/requester to take the vehicle to a dealer for diagnosis of the concern.
When performing a diagnostic check for an unsuccessful or incomplete OnStar(R) diagnostic
probe, or for concerns regarding completeness of the OnStar(R) Vehicle Diagnostic (OVD) e-mail,
verify that an aftermarket device was not present at the time of the requested probe. Regarding the
OVD e-mail, if an aftermarket device is interfering (including a Scan Tool of any type), the e-mail
will consistently display a "yellow" indication in diagnostics section for all vehicle systems except
the OnStar(R) System and Tire Pressure data (not available on all vehicles) will not be displayed
(i.e. section is collapsed). Successful diagnostic probes and complete OVD e-mails will resume
following the removal or disconnecting of the off-board device.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Memory Positioning Systems > Memory Positioning
Module > Component Information > Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Memory Positioning Systems > Seat Memory
Switch > Component Information > Locations
Seat Memory Switch: Locations
LH Front door on armrest
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Navigation System > Component Information >
Technical Service Bulletins > OnStar(R) - Aftermarket Device Interference Information
Navigation System: Technical Service Bulletins OnStar(R) - Aftermarket Device Interference
Information
INFORMATION
Bulletin No.: 08-08-46-004
Date: August 14, 2008
Subject: Information on Aftermarket Device Interference with OnStar(R) Diagnostic Services
Models: 2009 and Prior GM Passenger Car and Truck (including Saturn) 2009 and Prior HUMMER
H2, H3 Models 2009 and Prior Saab 9-7X
with OnStar(R) (RPO UE1)
This bulletin is being issued to provide dealer service personnel with information regarding
aftermarket devices connected to the Diagnostic Link Connector (DLC) and the impact to
OnStar(R) diagnostic probes and Vehicle Diagnostic e-mails.
Certain aftermarket devices, when connected to the Diagnostic Link Connector, such as, but not
limited to, Scan Tools, Trip Computers, Fuel Economy Analyzers and Insurance Tracking Devices,
interfere with OnStar's ability to perform a diagnostic probe when requested (via a blue button call)
by a subscriber. These devices also prohibit the ability to gather diagnostic and tire pressure data
for a subscriber's scheduled OnStar(R) Vehicle Diagnostic (OVD) e-mail.
These aftermarket devices utilize the Vehicles serial data bus to perform data requests and/or
information gathering. When these devices are requesting data, OnStar(R) is designed not to
interfere with any data request being made by these devices as required by OBD II regulations.
The OnStar(R) advisor is unable to definitively detect the presence of these devices and will only
be able to inform the caller or requester of the unsuccessful or incomplete probe and may in some
cases refer the subscriber/requester to take the vehicle to a dealer for diagnosis of the concern.
When performing a diagnostic check for an unsuccessful or incomplete OnStar(R) diagnostic
probe, or for concerns regarding completeness of the OnStar(R) Vehicle Diagnostic (OVD) e-mail,
verify that an aftermarket device was not present at the time of the requested probe. Regarding the
OVD e-mail, if an aftermarket device is interfering (including a Scan Tool of any type), the e-mail
will consistently display a "yellow" indication in diagnostics section for all vehicle systems except
the OnStar(R) System and Tire Pressure data (not available on all vehicles) will not be displayed
(i.e. section is collapsed). Successful diagnostic probes and complete OVD e-mails will resume
following the removal or disconnecting of the off-board device.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Compact Disc
Player (CD) > Component Information > Technical Service Bulletins > Customer Interest for Compact Disc Player (CD): >
649601 > Jan > 97 > Compact Disc Players - CD Changer Loading Procedures
Compact Disc Player (CD): Customer Interest Compact Disc Players - CD Changer Loading
Procedures
File In Section: 9 - Accessories
Bulletin No.: 64-96-01
Date: January, 1997
INFORMATION
Subject: Compact Disc Players - Procedures for Correct Use and Maintenance
Models: 1997 and Prior Passenger Cars and Trucks
CD Changer Loading Procedures
Because of differences in CD changer loading procedures, some confusion exists regarding this
issue. Although correct loading procedures are included with each changer's Owner's Manual,
often this information is not available to the dealer service personnel.
Verify proper loading when evaluating customer concerns of "CD inoperative".
Delco Electronics Product Type Loading Procedure
Radio w/intergral CD label side up
6 disc changer (LLAI) label side up
10 disc changer (FMI) label side up
12 disc changer (LLAI) label side down
Important:
Failure to load magazine/player correctly will disable the operation.
Important:
Only the 12 disc changer is to be loaded with the label side down.
CD Cleaners
Avoid use of commercially available CD cleaners.
The use of CD cleaners is not recommended and can damage the player's CD mechanism.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Compact Disc
Player (CD) > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Compact Disc
Player (CD): > 649601 > Jan > 97 > Compact Disc Players - CD Changer Loading Procedures
Compact Disc Player (CD): All Technical Service Bulletins Compact Disc Players - CD Changer
Loading Procedures
File In Section: 9 - Accessories
Bulletin No.: 64-96-01
Date: January, 1997
INFORMATION
Subject: Compact Disc Players - Procedures for Correct Use and Maintenance
Models: 1997 and Prior Passenger Cars and Trucks
CD Changer Loading Procedures
Because of differences in CD changer loading procedures, some confusion exists regarding this
issue. Although correct loading procedures are included with each changer's Owner's Manual,
often this information is not available to the dealer service personnel.
Verify proper loading when evaluating customer concerns of "CD inoperative".
Delco Electronics Product Type Loading Procedure
Radio w/intergral CD label side up
6 disc changer (LLAI) label side up
10 disc changer (FMI) label side up
12 disc changer (LLAI) label side down
Important:
Failure to load magazine/player correctly will disable the operation.
Important:
Only the 12 disc changer is to be loaded with the label side down.
CD Cleaners
Avoid use of commercially available CD cleaners.
The use of CD cleaners is not recommended and can damage the player's CD mechanism.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns
Radio/Stereo: Technical Service Bulletins Audio - Procedure To Handle Customer Radio Concerns
File In Section: 9 - Accessories
Bulletin No.: 68-96-O1A
Date: October, 1996
INFORMATION
Subject: Procedure to Handle Customer Radio Concerns
Models: 1997 and Prior Passenger Cars and Trucks
This bulletin is being revised to change the Sales Center Information to Service Center Information.
Please discard Corporate Bulletin Number 68-96-01 (Section 9 - Accessories).
Many of the radios being returned to the Delco Electronics remanufacturing centers have been
misdiagnosed. This misdiagnosis results in unnecessary customer comebacks, decreased
customer satisfaction and reduces the availability of exchange radios.
To resolve these issues, the following information was developed to give General Motors' dealers a
common service process to handle customer audio system concerns.
When a customer either calls or comes in with a concern about the radio system in their vehicle, it
is important that as much information as possible is gathered. This process begins with the Service
Consultant asking the customer specific questions related to their vehicle as outlined on the
Service Writer/Customer Check list.
Once the Service Consultant has completed the diagnostic worksheet, it should be attached to the
customer repair order for the technician. This worksheet should help the technician determine if the
concern is vehicle related or radio related. Two excellent service manuals are also available for this
purpose and are available from General Motors at the address shown below. A service bulletin,
34-92-12, Radio Frequency Interference Diagnosis, is also available as is assistance from the
Divisional Technical Assistance Centers.
Mascotech Mktg. Service 1972 Brown Road Auburn Hills, ML 48326 1-800-393-4831
Delco Electronics Sound Service Audio Systems Diagnostic Guide
P/N 19007.03-1A @ $10.00 per manual STG Audio Systems Training manual P/N 19007.03-2 @
$15.00 per manual
Repairs to the vehicle or the audio system can usually be done very quickly and the vehicle
returned to the customer that day. If the diagnosis indicates that the radio needs to be replaced,
remove the radio from the vehicle and order an exchange radio from your local AC Delco radio
exchange center. There are 28 approved AC Delco exchange centers nationally (listing attached).
If your local exchange center does not have the required exchange radio, it is important that you
contact the AC Delco locator service. This service can be found on the Service Parts TRACS
system 1-800-433-6961, prompt 4. It will be necessary to request overnight shipping so that the
owner's vehicle is retained at your dealership for only one night.
If the vehicle is kept overnight and it is a warranty repair, the customer should be offered courtesy
transportation or alternate transportation. Please do not return the vehicle with the suspect radio
installed or without a radio. Many of our vehicles today use a multiplex wiring system and the
vehicle will not run correctly without a radio.
When you receive the exchange radio, please return the removed radio to the AC Delco Exchange
Center within 24 hours (please enclose the diagnostic worksheet that the Service Consultant and
the Technician used with the removed radio along with the 1078 form). This will help the AC Delco
Exchange Center.
In the event you know the vehicle will need a radio before the customer brings the vehicle in, every
effort should be made to have a pre-exchanged radio available. A radio identification list is attached
to help you select the correct radio.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8471
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8472
AC Delco AUTHORIZED ELECTRONIC SERVICE CENTERS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8473
Duplicate form for your convenience SERVICE WRITER/CUSTOMER CHECK LIST
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8474
RECEPTION/NOISE CONCERN:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8475
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8476
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8477
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8478
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8479
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8480
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Audio - Procedure To Handle Customer Radio Concerns > Page
8481
1997 APPLICATIONS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Page 8482
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Page 8483
Radio/Stereo: Diagrams
Radio Receiver: C1
Radio
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Page 8484
Radio: C1 And C2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Radio/Stereo >
Component Information > Technical Service Bulletins > Page 8485
Radio/Stereo: Service and Repair
When installing radio, be sure to adjust antenna trimmer for peak reception. Also, be sure to
connect speaker before applying power to radio.
1. Disconnect battery ground cable. 2. Remove steering column lower trim panel, then remove
lefthand trim panel. 3. Remove radio bracket to instrument carrier attaching screws, then pull radio
and bracket assembly outward. 4. Disconnect radio and antenna electrical connectors. 5. Remove
radio to bracket attaching nuts, then remove radio. 6. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Speaker >
Component Information > Locations > Component Locations
Speaker: Component Locations
LH
LH Side of rear shelf
RH
RH Side of rear shelf
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Speaker >
Component Information > Locations > Component Locations > Page 8490
Speaker: Connector Locations
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Radio, Stereo, and Compact Disc > Speaker >
Component Information > Locations > Component Locations > Page 8491
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Alarm Module, (Vehicle Antitheft) > Component Information > Service and Repair
Alarm Module: Service and Repair
PROGRAMMING A NEW THEFT DETERRENT MODULE
IMPORTANT: Any new PASS-Key II Theft Deterrent Module will automatically program to the
resistance of the key (or interrogator setting) being used at the first ignition "ON" cycle. This can
only be done once for the life of the module.
New modules are unprogrammed. Before the system will function properly after a new module has
been installed, it must be programmed to the code that matches the customer1s keys.
Programming a new module is very simple:
1. Install the new, unprogrammed module. 2. Insert one of the customer's keys in the ignition lock
cylinder and turn it to the "ON" position. It's a good idea to start the Engine at this time to
verify system operation.
3. Observe the "PASSKEY" indicator Lamp:
^ The indicator lamp should light for about five seconds and then go out. If the wiring or contacts to
the Key Resistance Pellet or the key is defective or intermittent and a new module is installed, the
Engine will start but the "PASSKEY" indicator will flash at a rate of one flash per second until the
Ignition Switch is turned off. This indicates that the module did not program and that the system
components, wiring and contacts should be checked for a fault.
IMPORTANT: Before connecting the interrogrator to the ignition lock cylinder circuit, always verify
vehicle key code and set the code into the interrogrator using the "key code" knob. This will prevent
programming an unprogrammed module with an undesired key code.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Antenna Relay > Component Information > Locations > Power Antenna Relay
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Antenna Relay > Component Information > Locations > Power Antenna Relay > Page 8500
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Antitheft Relay > Component Information > Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Antitheft Relay > Component Information > Locations > Page 8504
Theft Deterrent Relay Daytime Running Lamps (DRL) Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Emergency Contact Module > Component Information > Technical Service Bulletins > OnStar(R) - Aftermarket
Device Interference Information
Emergency Contact Module: Technical Service Bulletins OnStar(R) - Aftermarket Device
Interference Information
INFORMATION
Bulletin No.: 08-08-46-004
Date: August 14, 2008
Subject: Information on Aftermarket Device Interference with OnStar(R) Diagnostic Services
Models: 2009 and Prior GM Passenger Car and Truck (including Saturn) 2009 and Prior HUMMER
H2, H3 Models 2009 and Prior Saab 9-7X
with OnStar(R) (RPO UE1)
This bulletin is being issued to provide dealer service personnel with information regarding
aftermarket devices connected to the Diagnostic Link Connector (DLC) and the impact to
OnStar(R) diagnostic probes and Vehicle Diagnostic e-mails.
Certain aftermarket devices, when connected to the Diagnostic Link Connector, such as, but not
limited to, Scan Tools, Trip Computers, Fuel Economy Analyzers and Insurance Tracking Devices,
interfere with OnStar's ability to perform a diagnostic probe when requested (via a blue button call)
by a subscriber. These devices also prohibit the ability to gather diagnostic and tire pressure data
for a subscriber's scheduled OnStar(R) Vehicle Diagnostic (OVD) e-mail.
These aftermarket devices utilize the Vehicles serial data bus to perform data requests and/or
information gathering. When these devices are requesting data, OnStar(R) is designed not to
interfere with any data request being made by these devices as required by OBD II regulations.
The OnStar(R) advisor is unable to definitively detect the presence of these devices and will only
be able to inform the caller or requester of the unsuccessful or incomplete probe and may in some
cases refer the subscriber/requester to take the vehicle to a dealer for diagnosis of the concern.
When performing a diagnostic check for an unsuccessful or incomplete OnStar(R) diagnostic
probe, or for concerns regarding completeness of the OnStar(R) Vehicle Diagnostic (OVD) e-mail,
verify that an aftermarket device was not present at the time of the requested probe. Regarding the
OVD e-mail, if an aftermarket device is interfering (including a Scan Tool of any type), the e-mail
will consistently display a "yellow" indication in diagnostics section for all vehicle systems except
the OnStar(R) System and Tire Pressure data (not available on all vehicles) will not be displayed
(i.e. section is collapsed). Successful diagnostic probes and complete OVD e-mails will resume
following the removal or disconnecting of the off-board device.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules
Relay Module: Customer Interest Electrical - MIL ON/DTC's Set By Various Control Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 8517
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 8518
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > Customer Interest for Relay Module: >
09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 8519
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for
Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules
Relay Module: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control
Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for
Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 8525
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for
Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 8526
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relays and Modules - Accessories and Optional
Equipment > Relay Module > Component Information > Technical Service Bulletins > All Technical Service Bulletins for
Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By Various Control Modules > Page 8527
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's
Set By Various Control Modules
Relay Module: Customer Interest Electrical - MIL ON/DTC's Set By Various Control Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's
Set By Various Control Modules > Page 8536
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's
Set By Various Control Modules > Page 8537
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > Customer Interest for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's
Set By Various Control Modules > Page 8538
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical MIL ON/DTC's Set By Various Control Modules
Relay Module: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control
Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical MIL ON/DTC's Set By Various Control Modules > Page 8544
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical MIL ON/DTC's Set By Various Control Modules > Page 8545
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Accessories and Optional Equipment > Relay Module > Component Information >
Technical Service Bulletins > All Technical Service Bulletins for Relay Module: > 09-06-03-004D > Dec > 10 > Electrical MIL ON/DTC's Set By Various Control Modules > Page 8546
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Bumper > Front Bumper > Front Bumper Cover / Fascia > System
Information > Technical Service Bulletins > Body - TPO Fascia Cleaning Prior to Painting
Front Bumper Cover / Fascia: Technical Service Bulletins Body - TPO Fascia Cleaning Prior to
Painting
INFORMATION
Bulletin No.: 08-08-51-002
Date: March 12, 2008
Subject: New Primer For TPO Fascias and Affected Cleaning Process of Painting Operation
Models: 2009 and Prior Passenger Cars and Trucks 2009 and Prior HUMMER H2, H3
The purpose of this bulletin is to inform the technician that General Motors has made a change in
the primer it uses for TPO plastic for service parts. This new primer comes in several different
colors from five different suppliers. This change affects the cleaning process of the painting
operation. The new process is as follows.
1. Wash with soap and water.
2. Clean with a 50% mix of isopropyl alcohol and water (or a waterborne cleaner). Check with your
paint supplier for product recommendations.
3. Scuff sand per your paint suppliers recommendations.
Note:
The use of a solvent-type cleaner will soften, or begin to dissolve the primer. Base coats do not
have any affect on this primer.
4. Reclean with a 50% mix of isopropyl alcohol and water (or a waterborne cleaner).
All fascias, with the exception of the Corvette, Camaro, and Cadillac XLR, are made of TPO. You
may find other TPO parts with this primer. If the technician has a question as to the type of plastic
they are painting, inspect the back of the part for the plastic symbol (TPO).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Bumper > Front Bumper > Front Bumper Reinforcement > System
Information > Technical Service Bulletins > Body - Polypropylene Energy Absorber Replacement
Front Bumper Reinforcement: Technical Service Bulletins Body - Polypropylene Energy Absorber
Replacement
Bulletin No.: 07-08-63-001
Date: April 17, 2007
INFORMATION
Subject: Information on Repair of Polypropylene Energy Absorbers
Models: 2007 and Prior GM Passenger Cars and Trucks (including Saturn) 2007 and Prior
HUMMER H2, H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to change the repair information. Please discard Corporate Bulletin
Number 63-20-02 (Section 8 - Body and Accessories).
Because the energy absorbers are relatively low in cost to replace, it is now more cost efficient to
replace the energy absorbers whenever they are damaged.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Bumper > Front Bumper > Front Bumper Shock Absorber > System
Information > Technical Service Bulletins > Polypropylene Foam Energy Absorbers - Repair
Front Bumper Shock Absorber: Technical Service Bulletins Polypropylene Foam Energy Absorbers
- Repair
File In Section: 10 - Body
Bulletin No.: 63-20-02
Date: September, 1996
INFORMATION
Subject: Repair of Polypropylene Foam Energy Absorbers
Models: 1997 and Prior Passenger Cars Using Polypropylene Foam Energy Absorbers
Some General Motors vehicles use a formed piece of Polypropylene foam as energy absorbers
behind fascias. These energy absorbers (EA) are designed to offer a measure of safety in the
event of a collision and have been engineered to withstand slight impacts (5 mph or less) with little
or no damage. However, in some instances, the EA may crack or even break.
The following information has been developed to offer an alternative to low impact EA
replacements. The foam EA can be identified in most cases by the symbol "PP" molded into the
surface. Following the procedure will allow the technician to repair an EA and return the vehicle to
the original crashworthiness state.
Polypropylene Foam EA Repair Procedure
1. If cracked or broken, make sure all the pieces of the EA are available for the repair.
Important:
If pieces of the EA are missing, the EA must be replaced.
2. Clean the areas to be bonded by brushing off any loose dirt or using soap and water, if
necessary.
Notice:
DO NOT USE SOLVENTS TO CLEAN POLYPROPYLENE EA. The use of solvents may result in
damage to the EA.
3. Using a 3M POLYGUN TC HOT MELT APPLICATOR GUN* and 3M JETMELT ADHESIVE #
3764*, apply adhesive to the parts by following the instructions for the applicator gun. Ensure
complete wet out of the adhesive on the repair surfaces during reassembly of the EA.
Important:
The adhesive has a 40 second "work time" and requires a 2 minute "clamp time". Allow 20 minutes
for the adhesive to fully cure.
The "3M Polygun TC Hotmelt Applicator Gun" and "3M Jetmelt Adhesive # 3764" can be obtained
by calling DIRECTECH at 1-800-877-9344 or 612-941-2616.
* We believe this source and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such items which may be available from
other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Bumper > Rear Bumper > Rear Bumper Cover / Fascia > System
Information > Technical Service Bulletins > Body - TPO Fascia Cleaning Prior to Painting
Rear Bumper Cover / Fascia: Technical Service Bulletins Body - TPO Fascia Cleaning Prior to
Painting
INFORMATION
Bulletin No.: 08-08-51-002
Date: March 12, 2008
Subject: New Primer For TPO Fascias and Affected Cleaning Process of Painting Operation
Models: 2009 and Prior Passenger Cars and Trucks 2009 and Prior HUMMER H2, H3
The purpose of this bulletin is to inform the technician that General Motors has made a change in
the primer it uses for TPO plastic for service parts. This new primer comes in several different
colors from five different suppliers. This change affects the cleaning process of the painting
operation. The new process is as follows.
1. Wash with soap and water.
2. Clean with a 50% mix of isopropyl alcohol and water (or a waterborne cleaner). Check with your
paint supplier for product recommendations.
3. Scuff sand per your paint suppliers recommendations.
Note:
The use of a solvent-type cleaner will soften, or begin to dissolve the primer. Base coats do not
have any affect on this primer.
4. Reclean with a 50% mix of isopropyl alcohol and water (or a waterborne cleaner).
All fascias, with the exception of the Corvette, Camaro, and Cadillac XLR, are made of TPO. You
may find other TPO parts with this primer. If the technician has a question as to the type of plastic
they are painting, inspect the back of the part for the plastic symbol (TPO).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Bumper > Rear Bumper > Rear Bumper Reinforcement > System
Information > Technical Service Bulletins > Body - Polypropylene Energy Absorber Replacement
Rear Bumper Reinforcement: Technical Service Bulletins Body - Polypropylene Energy Absorber
Replacement
Bulletin No.: 07-08-63-001
Date: April 17, 2007
INFORMATION
Subject: Information on Repair of Polypropylene Energy Absorbers
Models: 2007 and Prior GM Passenger Cars and Trucks (including Saturn) 2007 and Prior
HUMMER H2, H3 2005-2007 Saab 9-7X
Supercede:
This bulletin is being revised to change the repair information. Please discard Corporate Bulletin
Number 63-20-02 (Section 8 - Body and Accessories).
Because the energy absorbers are relatively low in cost to replace, it is now more cost efficient to
replace the energy absorbers whenever they are damaged.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Bumper > Rear Bumper > Rear Bumper Shock Absorber > System
Information > Technical Service Bulletins > Polypropylene Foam Energy Absorbers - Repair
Rear Bumper Shock Absorber: Technical Service Bulletins Polypropylene Foam Energy Absorbers
- Repair
File In Section: 10 - Body
Bulletin No.: 63-20-02
Date: September, 1996
INFORMATION
Subject: Repair of Polypropylene Foam Energy Absorbers
Models: 1997 and Prior Passenger Cars Using Polypropylene Foam Energy Absorbers
Some General Motors vehicles use a formed piece of Polypropylene foam as energy absorbers
behind fascias. These energy absorbers (EA) are designed to offer a measure of safety in the
event of a collision and have been engineered to withstand slight impacts (5 mph or less) with little
or no damage. However, in some instances, the EA may crack or even break.
The following information has been developed to offer an alternative to low impact EA
replacements. The foam EA can be identified in most cases by the symbol "PP" molded into the
surface. Following the procedure will allow the technician to repair an EA and return the vehicle to
the original crashworthiness state.
Polypropylene Foam EA Repair Procedure
1. If cracked or broken, make sure all the pieces of the EA are available for the repair.
Important:
If pieces of the EA are missing, the EA must be replaced.
2. Clean the areas to be bonded by brushing off any loose dirt or using soap and water, if
necessary.
Notice:
DO NOT USE SOLVENTS TO CLEAN POLYPROPYLENE EA. The use of solvents may result in
damage to the EA.
3. Using a 3M POLYGUN TC HOT MELT APPLICATOR GUN* and 3M JETMELT ADHESIVE #
3764*, apply adhesive to the parts by following the instructions for the applicator gun. Ensure
complete wet out of the adhesive on the repair surfaces during reassembly of the EA.
Important:
The adhesive has a 40 second "work time" and requires a 2 minute "clamp time". Allow 20 minutes
for the adhesive to fully cure.
The "3M Polygun TC Hotmelt Applicator Gun" and "3M Jetmelt Adhesive # 3764" can be obtained
by calling DIRECTECH at 1-800-877-9344 or 612-941-2616.
* We believe this source and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such items which may be available from
other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Doors > Front Door > Front Door Window
Glass > System Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information
Front Door Window Glass: Technical Service Bulletins Body - Vehicle Glass Distortion Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Doors > Front Door > Front Door Window
Glass > System Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information > Page 8582
Front Door Window Glass: Technical Service Bulletins Body - Side Window Chipping Information
INFORMATION
Bulletin No.: 06-08-64-001B
Date: October 20, 2009
Subject: Information on Side Door Window Glass Chipping Caused by Hanging Vehicle Key Lock
Box
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add vehicles and model years and to include all types of
door window glass. Please discard Corporate Bulletin Number 06-08-64-001A (Section 08 - Body &
Accessories).
- In several warranty parts review cases, side door window glass was observed with a chip or chips
on the top side of the window glass. Dealer contacts confirmed that they use a vehicle key lock box
on the front side door window glass.
- A random selection of side door glass returns will be conducted to confirm adherence. If a side
door glass is discovered with a chip or chips in the location previously described, the side door
glass will be returned to the dealership for debit.
Example of Side Door Glass
- DO NOT place a vehicle key lock box on a side door window glass.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Doors > Front Door > Front Door Window
Glass > System Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information > Page 8583
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Hood > Hood Latch > Component Information
> Locations > Hood Latch Assembly
LH Radiator Support
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Hood > Hood Latch > Component Information
> Locations > Hood Latch Assembly > Page 8589
Front Of Radiator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Power Trunk / Liftgate Lock
Actuator > Component Information > Locations
Rear Luggage Compartment With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Latch >
Component Information > Technical Service Bulletins > Trap Resistant Trunk Kit - Function/Installation
Trunk / Liftgate Latch: Technical Service Bulletins Trap Resistant Trunk Kit - Function/Installation
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-66-002A
Date: January, 2000
Subject: Trap Resistant Rear Compartment (Trunk) Kit
Models: 1990-2000 Passenger Cars with Rear Compartments Except: 1990-1991 Buick Reatta
2000
Buick LeSabre
1990-1993 Cadillac Allante, Fleetwood Brougham 1997-2000 Cadillac Seville 2000
Cadillac Deville
1990 Chevrolet Caprice
1990-1991 Chevrolet Cavalier 1990-1996 Chevrolet Beretta 1990-2000 Chevrolet Metro, Prizm
1998-2000 Chevrolet Corvette 2000
Chevrolet Impala
1990-1992 Oldsmobile Toronado/Trofeo 1990-1991 Pontiac Sunbird 1990-1993 Pontiac LeMans
2000
Pontiac Bonneville
This bulletin is being revised to add additional models and new part numbers. Please discard
Corporate Bulletin Number 99-O8-66-002 (Section 08 - Body and Accessories).
The purpose of this bulletin is to inform dealership personnel about the Trap Resistant Rear
Compartment (Trunk) Kit, including the system function, necessary vehicle modifications and part
numbers required to install the kit.
The Trap Resistant Rear Compartment kit is composed of three main system components; one of
which (the Rear Seat Tether), may or may not be needed, depending on the vehicle being retrofit.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Latch >
Component Information > Technical Service Bulletins > Trap Resistant Trunk Kit - Function/Installation > Page 8598
The first component of the kit is the illuminated Interior Release Handle (1). The Release Handle is
mounted inside the rear compartment to the deck lid. This handle was designed so that a small
child trapped in the rear compartment could use it to open the deck lid. The handle operates the
deck lid latch mechanically, but is illuminated with two LED's when the deck lid is closed. The
handle remains illuminated for a period of about one hour after the deck lid is closed. The LED's
create a small parasitic load that will not drain the vehicle battery with normal usage.
The second component of the kit is the Trap Resistant Latch (2). the Trap Resistant Latch is a
modified deck lid latch designed to help prevent a child from unintentionally closing and latching the
deck lid. The Trap Resistant Latch opens the rear compartment normally through all current means
(key, RKE or passenger compartment release) but cannot be re-latched without the user
performing a reset function. This reset function consists of pushing up on a small knob (3), while
simultaneously pushing a slide mechanism to the right (4). Once the slide mechanism is fully
pushed over, the small knob can be released. This function is a simple on-hand operation for an
adult, but is difficult for a young child to perform. If the latch is not enabled, the deck lid will not
latch and the rear compartment will not close.
The third component is the Rear Seat Tether Kit. If the vehicle is equipped with a pass-through to
the rear compartment and the folding rear seat can be unlatched from within the passenger
compartment without the use of a key or other unlocking feature, then a Rear Seat Tether must be
installed. This tether helps prevent a child from gaining access to the rear compartment of a vehicle
from the passenger compartment by allowing a secondary lock of the seatback. The Rear Seat
Tether employs one or two tethers (one per folding seatback), each permanently connected to a
T-handle anchor mounted in the rear compartment. To lock the folding seatback, the user can
partially fold the seatback and attach the tether to another T-handle anchor mounted to the
seatback. When the tether is affixed to both T-handle anchors, the seat cannot be folded down. To
fold down the seatback, the tether must be removed from the anchor attached to the seatback.
Important:
Installation of the Trap Resistant Latch on some vehicles may require sheet metal and/or trim
modifications to the rear compartment striker area. These modifications should be communicated
with the customer prior to installations. Also, installation of the Trap Resistant Latch requires a rear
compartment lid "ajar" switch. Prior to ordering the Trap Resistant Rear Compartment Kit, inspect
the old deck lid latch to see if it is equipped with an "ajar" switch. If the vehicle is not equipped with
this switch, P/N 12506174 must be ordered.
After completing the Trap Resistant Rear Compartment Kit installation, provide the customer with
the supplemental Owner's Manual insert included in the kit and demonstrate the system function.
This program is specially structured for a single purchase price to the owner. The owner is
responsible to pay a maximum of $50.00 U.S.; $80.00 Canadian for parts and labor to install the
complete Trap Resistant Rear Compartment Kit and Rear Seat Tether(s), if required.
Parts Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Latch >
Component Information > Technical Service Bulletins > Trap Resistant Trunk Kit - Function/Installation > Page 8599
Parts are currently available from GMSPO.
Labor Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Relay >
Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Solenoid >
Component Information > Locations
Trunk / Liftgate Solenoid: Locations
Trunk Lid
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Switch >
Component Information > Locations > Component Locations
Trunk / Liftgate Switch: Component Locations
Trunk Lid With Pull-Down
Back View Of LH Instrument Panel
Rear Compartment Lid Enable Switch
Mounted on I/P Compartment
Rear Luggage Compartment With Pull-Down
Rear Compartment Lid Pull-Down Striker Switch
Attached to Rear Compartment Lid Pulldown Actuator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Switch >
Component Information > Locations > Component Locations > Page 8610
Rear Compartment Lid Pull-Down Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Switch >
Component Information > Locations > Component Locations > Page 8611
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Doors, Hood and Trunk > Trunk / Liftgate > Trunk / Liftgate Switch >
Component Information > Locations > Page 8612
Rear Glass Interlock/Push Button Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Exterior Moulding / Trim > Body Emblem > Component Information >
Technical Service Bulletins > 06-08-111-004B - BULLETIN CANCELLATION NOTIFICATION
Body Emblem: Technical Service Bulletins 06-08-111-004B - BULLETIN CANCELLATION
NOTIFICATION
TECHNICAL
Bulletin No.: 06-08-111-004B
Date: September 25, 2009
Subject: Information on Discoloration, Blistering, Peeling or Erosion of Various Exterior Emblems
Including Chevy Bowtie (Bulletin Cancelled)
Models:
2009 and Prior GM Passenger Cars and Trucks (including Saturn) 2003-2009 HUMMER H2
2006-2009 HUMMER H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being cancelled. Please discard Corporate Bulletin Number
06-08-111-004A (Section 08 - Body & Accessories).
This bulletin is being cancelled. The information is no longer applicable.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Frame > Cross-Member > Component Information > Locations
Cross-Member: Locations
Center Of Rear Crossmember
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Frame > Cross-Member > Component Information > Locations > Page
8622
Antilock Brake System Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Ash Tray > Component Information >
Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Carpet > Component Information > Technical
Service Bulletins > Interior - Proper Use of Floor Mats
Carpet: Technical Service Bulletins Interior - Proper Use of Floor Mats
INFORMATION
Bulletin No.: 10-08-110-001
Date: March 30, 2010
Subject: Information on Proper Use of Floor Mats
Models:
2011 and Prior GM Passenger Cars and Trucks (Including Saturn) 2003-2009 HUMMER H2
2006-2010 HUMMER H3, H3T 2005-2009 Saab 9-7X
GM's carpeted and all-weather (rubber) floor mats are especially designed for use in specific GM
vehicles. Using floor mats that were not designed for the specific vehicle or using them incorrectly
may cause interference with the accelerator or brake pedal. Please review the following safety
guidelines regarding proper driver's side floor mat usage with the customer.
Warning
If a floor mat is the wrong size or is not properly installed, it can interfere with the accelerator pedal
and/or brake pedal. Interference with the pedals can cause unintended acceleration and/or
increased stopping distance which can cause a crash and injury. Make sure the floor mat does not
interfere with the accelerator or brake pedal.
- Do not flip the driver's floor mat over (in an effort to keep the floor mat clean)
- Do not place anything on top of the driver's floor mat (e.g. carpet remnant, towel)
- Do not place another mat on top of the driver's floor mat (e.g. do not place all-weather rubber
mats over carpeted floor mats)
- Only use floor mats that are designed specifically for your vehicle
- When using replacement mats, make certain the mats do not interfere with the accelerator or
brake pedal before driving the vehicle
If your vehicle is equipped with a floor mat retaining pin(s) or clip(s), make certain the mat is
installed correctly and according to the instructions.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Carpet > Component Information > Technical
Service Bulletins > Interior - Proper Use of Floor Mats > Page 8631
After installing floor mats, make certain they cannot move and do not interfere with the accelerator
or brake pedals.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Carpet > Component Information > Technical
Service Bulletins > Interior - Proper Use of Floor Mats > Page 8632
Carpet: Technical Service Bulletins Interior - Elimination Of Unwanted Odors
INFORMATION
Bulletin No.: 00-00-89-027E
Date: September 29, 2008
Subject: Eliminating Unwanted Odors in Vehicles
Models: 2009 and Prior GM Passenger Cars and Trucks (including Saturn) 2009 and Prior
HUMMER H2, H3 Vehicles 2009 and Prior Saab 9-7X
Supercede:
This bulletin is being revised to add model years and refine the instructions. Please discard
Corporate Bulletin Number 00-00-89-027D (Section 00 - General Information).
Vehicle Odor Elimination
General Motors offers a product that may control or eliminate odors in the interior and luggage
compartment areas of GM vehicles. GM Vehicle Care Odor Eliminator is a non-toxic,
biodegradable odor remover. This odorless product has been shown to greatly reduce or remove
objectionable smells of mold and mildew resulting from vehicle water leaks (as well as customer
created odors, i.e. smoke). You may use GM Vehicle Care Odor Eliminator on fabrics, vinyl,
leather, carpet and sound deadening materials. It may also be induced into HVAC modules and
instrument panel ducts (for the control of non-bacterial related odors).
Important:
This product leaves no residual scent and should not be sold as or considered an air freshener.
Product action may result in the permanent elimination of an odor and may be preferable to
customers with allergies who are sensitive to perfumes.
How to Use This Product
GM Vehicle Care Odor Eliminator may be sprayed on in a ready-to-use formula or used in steam
cleaners as an additive with carpet shampoo. This water-based, odorless product is safe for all
vehicle interiors. Do not wet or soak any interior surface that plain water would cause to
deteriorate, as this product will have the same effect. Also avoid letting this product come into
contact with vinegar or any acidic substance. Acid-based products will hamper the effectiveness of,
or render GM Vehicle Care Odor Eliminator inert.
Note:
Complete eight page treatment sheets are enclosed within each case of GM Vehicle Care Odor
Eliminator. These treatment instructions range from simple vehicle odor elimination to full step by
step procedures for odor removal from water leaks. If lost, contact 800-977-4145 to get a
replacement set faxed or e-mailed to your dealership.
Instructions and cautions are printed on the bottle, but additional help is available. If you encounter
a difficult to eliminate or reoccurring odor, you may call 1-800-955-8591 (in Canada,
1-800-977-4145) to obtain additional information and usage suggestions.
Important:
This product may effectively remove odors when directly contacting the odor source. It should be
used in conjunction with diagnostic procedures (in cases such as a water leak) to first eliminate the
root cause of the odor, and then the residual odor to permanently correct the vehicle condition.
Vehicle Waterleak Odor Elimination
STEP ONE:
Confirm that all water leaks have been repaired. Determine what areas of the vehicle were water
soaked or wet. Components with visible mold/mildew staining should be replaced. Isolate the odor
source inside the vehicle. Often an odor can be isolated to an area or component of the vehicle
interior by careful evaluation. Odor evaluation may need to be performed by multiple persons.
Another method of isolating an odor source is to remove and segregate interior trim and
components. Plastic sheeting or drop cloths can be used to confine seats, headliners, etc. to assist
in evaluation and diagnoses. If appropriate the vehicle and interior trim should be evaluated
separately to determine if the odor stays with the vehicle or the interior components. Odors that
stay with the vehicle may be isolated to insulating and sound deadening materials (i.e. water leak
at the windshield or standing water in the front foot well area caused mold/mildew to form on the
bulkhead or kick panel sound deadening pads. If the interior is removed the floor pan and
primed/painted surfaces should be treated with bleach/soap solution, rinsed with clean water and
dried. Interior surfaces should then be treated with GM Vehicle Care Odor Eliminator product
before reinstalling carpet or reassembling.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Carpet > Component Information > Technical
Service Bulletins > Interior - Proper Use of Floor Mats > Page 8633
The GM Vehicle Care Odor Eliminator product is an effective odor elimination product when used
properly. It must come into direct contact with the odor source. It should be used in conjunction with
diagnostic procedures to first eliminate the root cause of the odor. Some procedures for use after
odor root cause correction are:
STEP TWO:
^ Use the trigger spray head.
^ Put a drop of dish soap the size of a quarter in the bottom of a bottle.
^ Add 8 oz. of GM Vehicle Care Odor Eliminator (1 cup) to the dish soap and top off the bottle with
tap water.
^ This formula should be used on hard surfaces (dash, interior plastic molding, and floor pan)
STEP THREE:
The third step to neutralizing the vehicle is a light to medium treatment of all carpeting and
upholstered seats with the GM Vehicle Care Odor Eliminator formula and a wide fan spray setting
(at full strength) (i.e.: carpeting on the driver's side requires 4-5 triggers pulls for coverage). The
headliner and trunk should be sprayed next. Lightly brushing the formula into the carpeting and
upholstery is a recommended step for deep odor problems. The dash and all hard surfaces should
be sprayed with dish soap/water mixture. Let stand for 1-2 minutes then wipe off the surface.
STEP FOUR: (vehicle ventilation system treatment)
The ventilation system is generally the last step in the treatment of the vehicle.
a. Spray the GM Vehicle Care Odor Eliminator formula into all dash vents. (1-2 trigger pulls per
vent).
b. Start the vehicle and turn the vehicle fan on high cool (not A/C setting).
c. Spray the formula (10 trigger pulls) into the outside fresh air intake vent (cowl at base of
windshield)
d. Enter the vehicle after 1 minute and wipe off the excess formula spurting out of the dash vents.
e. Smell the air coming from the dash vents. If odors are still present, spray another 5 triggers into
the cowl, wait another minute and smell the results. Once you have obtained a fresh, clean smell
coming from the vents, turn the system to the A/C re-circulation setting. Roll up the windows, spray
3-5 pumps into the right lower IP area and let the vehicle run with the fan set on high for 5-7
minutes.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited
is resolved without completing every step, the remaining steps do not need to be performed. If
these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
Additional Suggestions to Increase Customer Satisfaction
Here are some additional ideas to benefit your dealership and to generate greater customer
enthusiasm for this product.
^ Keep this product on-hand for both the Service Department and the Used Car lot. Add value to
your used car trades; treat loaner and demo cars during service and at final sale to eliminate
smoke, pet, and other common odors offensive to customers. Make deodorizing a vehicle part of
your normal vehicle detailing service.
^ Consider including GM Vehicle Care Odor Eliminator as a give-away item with new vehicle
purchases. Many dealers give away as "gifts" various cleaning supplies at time of delivery. GM
Odor Eliminator is one of a few products GM offers that has as many uses in the home as in the
vehicle. Customers may find this product can be used for a host of recreational activities
associated with their new vehicle, such as deodorizing a boat they tow, or a camper.
^ GM Odor Eliminator and many of the GM Vehicle Care products offer you the chance to increase
dealership traffic as these superior quality products cannot be purchased in stores. Many
Dealerships have product displays at the parts counter. Consider additional displays in the
Customer Service Lounge, the Showroom and at the Service Desk or Cashier Window. Many
customers who purchase vehicles and receive regular maintenance at your dealership may never
visit the parts counter, and subsequently are not exposed to the variety and value that these
products offer.
Parts Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Carpet > Component Information > Technical
Service Bulletins > Interior - Proper Use of Floor Mats > Page 8634
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Dash Board / Instrument Panel <-->
[Dashboard / Instrument Panel] > Air Bag(s) Arming and Disarming > System Information > Service and Repair > Air Bag
Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Dash Board / Instrument Panel <-->
[Dashboard / Instrument Panel] > Air Bag(s) Arming and Disarming > System Information > Service and Repair > Air Bag
Disarming and Arming > Page 8640
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Glove Compartment > Component Information
> Technical Service Bulletins > I/P Compartment Door Latch/Lock Cylinder - Revised R&R;
Glove Compartment: Technical Service Bulletins I/P Compartment Door Latch/Lock Cylinder Revised R&R;
File In Section: 8 - Chassis/Body Electrical
Bulletin No.: 63-83-05
Date: March, 1996
SERVICE MANUAL UPDATE
Subject: Section 8C - Revised Remove/Install Procedure for I/P Compartment Door Latch and Lock
Cylinder Assembly
Models: 1994-96 Buick Roadmaster 1994-96 Cadillac Fleetwood 1994-96 Chevrolet Caprice,
Impala
This bulletin is being issued to revise the remove/install procedure for the I/P compartment door
latch and lock cylinder assembly in Section 8C of the Service Manual.
Instrument Panel compartment Door Latch and Lock Cylinder Assembly
Figure 1 (Numbers indicated in parenthesis below refer to callout in Figure 1.)
Remove or Disconnect
1. Open instrument panel (I/P) compartment door (6).
2. Bolts/screws (8) from door latch assembly.
3. Latch assembly from compartment door (6).
4. Place latch in lock position.
5. Lock cylinder assembly (5) from door latch assembly.
a. Turn lock cylinder assembly (5) to lock position and remove key.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Interior Moulding / Trim > Glove Compartment > Component Information
> Technical Service Bulletins > I/P Compartment Door Latch/Lock Cylinder - Revised R&R; > Page 8645
b. Using awl or paper clip, slightly depress lock tumbler by inserting paper clip through hole at base
of cylinder housing.
c. Insert key and remove awl or paper clip.
d. Turn key and cylinder to full clockwise position (key head upside down).
e. Remove lock cylinder assembly (5).
Install or Connect
1. Lock cylinder assembly (5) to door latch assembly (5).
a. Depress all lock tumblers on lock cylinder (5) with finger.
b. Insert key into lock cylinder assembly (5).
c. Insert key and lock cylinder assembly (5) into latch (key head upside down).
d. Turn key to full counterclockwise position (key head right side up).
e. Remove key.
2. Bolts/screws (8) attaching latch to I/P compartment door assembly (6).
Tighten Tighten bolts/screws (8) to 1.9 N.m (17 lb. in.).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Key > Component Information > Technical Service Bulletins >
Locks - Key Code Security Rules and Information
Key: Technical Service Bulletins Locks - Key Code Security Rules and Information
INFORMATION
Bulletin No.: 10-00-89-010
Date: May 27, 2010
Subject: Key Code Security Rules and Information on GM KeyCode Look-Up Application (Canada
Only)
Models:
2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER H2, H3 2009 and Prior
Saturn and Saab 2002 and Prior Isuzu
Attention:
This bulletin has been created to address potential issues and questions regarding KeyCode
security. This bulletin should be read by all parties involved in KeyCode activity, including dealer
operator, partner security coordinator, sales, service and parts departments. A copy of this bulletin
should be printed and maintained in the parts department for use as a reference.
Important U.S. dealers should refer to Corporate Bulletin Number 10-00-89-009.
Where Are Key Codes Located?
General Motors provides access to KeyCodes through three sources when a vehicle is delivered to
a dealer. Vehicle KeyCodes are located on the original vehicle invoice to the dealership. There is a
small white bar coded tag sent with most new vehicles that also has the key code printed on it.
Dealerships should make a practice of comparing the tag's keycode numbers to the keycode listed
on the invoice. Any discrepancy should be reported immediately to the GM of Canada Key Code
Inquiry Desk. Remember to remove the key tag prior to showing vehicles to potential customers.
The third source for Key codes is through the GM KeyCode Look-Up feature within the
OEConnection D2DLink application. KeyCode Look-Up currently goes back 17 previous model
years from the current model year.
When a vehicle is received by the dealership, care should be taken to safeguard the original
vehicle invoice and KeyCode tag provided with the vehicle. Potential customers should not have
access to the invoice or this KeyCode tag prior to the sale being completed. After a sale has been
completed, the KeyCode information belongs to the customer and General Motors.
Tip
Only the original invoice contains key code information, a re-printed invoice does not.
GM KeyCode Look-Up Application for GM of Canada Dealers
All dealers should review the General Motors of Canada KeyCode Look-Up Policies and
Procedures (Service Policy & Procedures Manual Section 3.1.6 "Replacement of VIN plates &
keys").
Please note that the KeyCode Access site is restricted. Only authorized users should be using this
application. Please see your Parts Manager for site authorized users. KeyCode Look-Up currently
goes back 17 years from current model year.
Important notes about security:
- Users may not access the system from multiple computers simultaneously.
- Users may only request one KeyCode at a time.
- KeyCode information will only be available on the screen for 2 minutes.
- Each user is personally responsible for maintaining and protecting their password.
- Never share your password with others.
- User Id's are suspended after 6 consecutive failed attempts.
- User Id's are disabled if not used for 90 days.
- Processes must be in place for regular dealership reviews.
- The Parts Manager (or assigned management) must have processes in place for employee
termination or life change events. Upon termination individuals access must be turned off
immediately and access should be re-evaluated upon any position changes within the dealership.
- If you think your password or ID security has been breached, contact Dealer Systems Support at
1-800-265-0573.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Key > Component Information > Technical Service Bulletins >
Locks - Key Code Security Rules and Information > Page 8651
Each user will be required to accept the following agreement each time the KeyCode application is
used.
Key Code User Agreement
- Key codes are proprietary information belonging to General Motors Corporation and to the vehicle
owner.
- Unauthorized access to, or use of, key code information is unlawful and may subject the user to
criminal and civil penalties.
- This information should be treated as strictly confidential and should not be disclosed to anyone
unless authorized.
I will ensure that the following information is obtained prior to releasing any Key Code information:
1. Government issued picture ID (Drivers License) 2. Registration or other proof of ownership.
Registration should have normal markings from the Province that issued the registration and
possibly the
receipt for payment recorded as well.
Important
- GM takes this agreement seriously. Each user must be certain of vehicle ownership before giving
out key codes.
- When the ownership of the vehicle is in doubt, dealership personnel should not provide the
information.
Key code requests should never be received via a fax or the internet and key codes should never
be provided to anyone in this manner. A face to face contact with the owner of the vehicle is the
expected manner that dealers will use to release a key code or as otherwise stipulated in this
bulletin or other materials.
- Key codes should NEVER be sent via a fax or the internet.
- Each Dealership should create a permanent file to document all KeyCode Look Up transactions.
Requests should be filed by VIN and in each folder retain copies of the following:
- Government issued picture ID (Drivers License)
- Registration or other proof of ownership.
- Copy of the paid customer receipt which has the name of the employee who cut and sold the key
to the customer.
- Do not put yourself or your Dealership in the position of needing to "explain" a KeyCode Look Up
to either GM or law enforcement officials.
- Dealership Management has the ability to review all KeyCode Look-Up transactions.
- Dealership KeyCode documentation must be retained for two years.
Frequently Asked Questions (FAQs) for GM of Canada Dealers
How do I request a KeyCode for customer owned vehicle that is not registered?
Scrapped, salvaged or stored vehicles that do not have a current registration should still have the
ownership verified by requesting the vehicle title, current insurance policy and / or current lien
holder information from the customers financing source. If you cannot determine if the customer is
the owner of the vehicle, do not provide the key code information. In these cases, a short
description of the vehicle (scrapped, salvaged, etc.) and the dealership location should be kept on
file. Any clarifying explanation should be entered into the comments field.
How do I document a KeyCode request for a vehicle that is being repossessed?
The repossessor must document ownership of the vehicle by providing a court ordered
repossession order and lien-holder documents prior to providing key code information. Copies of
the repossessors Drivers License and a business card should be retained by the dealership for
documentation.
What do I do if the registration information is locked in the vehicle?
Every effort should be made to obtain complete information for each request. Each Dealership will
have to decide on a case by case basis if enough information is available to verify the customer's
ownership of the vehicle. Other forms of documentation include vehicle title, insurance policy, and
or current lien information from the customers financing source. Dealership Management must be
involved in any request without complete information. If you cannot determine if the customer is the
owner of the vehicle, do not provide the key code information.
Can I get a print out of the information on the screen?
It is important to note that the Key Code Look Up Search Results contain sensitive and/or
proprietary information. For this reason GM recommends against printing it. If the Search Results
must be printed, store and/or dispose of the printed copy properly to minimize the risk of improper
or illegal use.
Who in the dealership has access to the KeyCode application?
Dealership Parts Manager (or assigned management) will determine, and control, who is
authorized to access the KeyCode Look Up application. However, we anticipate that dealership
parts and service management will be the primary users of the application. The KeyCode Look Up
application automatically tracks each user activity session. Information tracked by the system
includes: User name, User ID, all other entered data and the date/time of access.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Key > Component Information > Technical Service Bulletins >
Locks - Key Code Security Rules and Information > Page 8652
What if I input the VIN incorrectly?
If an incorrect VIN is entered into the system (meaning that the system does not recognize the VIN
or that the VIN has been entered incorrectly) the system will return an error message.
If I am an authorized user for the KeyCode application, can I access the application from home?
Yes.
What if I suspect key code misuse?
Your dealership should communicate the proper procedures for requesting key codes. Any
suspicious activity either within the dealership or externally should be reported to Dealer Systems
Support at 1-800-265-0573 or GM of Canada Key Code Inquiry Desk at 1-905-644-4892.
Whose key codes can I access through the system?
At this time the following Canadian vehicle codes are available through the system: Chevrolet,
Cadillac, Buick, Pontiac, GMC, HUMMER (H2 and H3 only), Oldsmobile, Saturn, Saab and Isuzu
(up to 2002 model year) for a maximum of 17 model years.
What should I do if I enter a valid VIN and the system does not produce any key code information?
Occasionally, the KeyCode Look Up application may not produce a key code for a valid VIN. This
may be the result of new vehicle information not yet available. In addition, older vehicle information
may have been sent to an archive status. If you do not receive a key code returned for valid VIN,
you should contact GM of Canada Key Code Inquiry Desk at 1-905-644-4892.
How do I access KeyCodes if the KeyCode Look-up system is down?
If the KeyCode Look-up system is temporarily unavailable, you can contact the original selling
dealer who may have it on file or contact GM of Canada Key Code Inquiry Desk at
1-905-644-4892. If the customer is dealing with an emergency lock-out situation, you need to have
the customer contact Roadside assistance, OnStar if subscribed, or 911.
What should I do if the KeyCode from the look-up system does not work on the vehicle?
On occasion a dealer may encounter a KeyCode that will not work on the vehicle in question. In
cases where the KeyCode won't work you will need to verify with the manufacturer of the cutting
equipment that the key has been cut correctly. If the key has been cut correctly you may be able to
verify the proper KeyCode was given through the original selling dealer. When unable to verify the
KeyCode through the original selling dealer contact GM of Canada Key Code Inquiry Desk at
1-905-644-4892. If the key has been cut correctly and the code given does not work, the lock
cylinder may have been changed. In these situations following the proper SI document for recoding
a key or replacing the lock cylinder may be necessary.
How long do I have to keep KeyCode Records?
Dealership KeyCode documentation must be retained for two years.
Can I get a KeyCode changed in the Look-Up system?
Yes, KeyCodes can be changed in the Look-Up system if a lock cylinder has been changed.
Contact GM of Canada Key Code Inquiry Desk at 1-905-644-4892.
What information do I need before I can provide a driver of a company fleet vehicle Keys or
KeyCode information?
The dealership should have a copy of the individual's driver's license, proof of employment and
registration. If there is any question as to the customer's employment by the fleet company, the
dealer should attempt to contact the fleet company for verification. If there is not enough
information to determine ownership and employment, this information should not be provided.
How do I document a request from an Independent Repair facility for a KeyCode or Key?
The independent must provide a copy of their driver's license, proof of employment and signed
copy of the repair order for that repair facility. The repair order must include customer's name,
address, VIN, city, province and license plate number. Copies of this information must be included
in your dealer KeyCode file.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Key > Component Information > Technical Service Bulletins >
Locks - Key Code Security Rules and Information > Page 8653
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Programming Connector > Component Information > Locations
Keyless Entry Programming Connector: Locations
LH Luggage Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Receiver > Component Information > Locations
Rear Shelf, Top View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Receiver > Component Information > Locations > Page 8661
Keyless Entry Receiver: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Receiver > Component Information > Locations > Page 8662
C406: Body Harness To Tailgate Harness, Headlamp Automatic Control Module (C1), Remote
Control Door Lock Receiver
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Transmitter > Component Information > Technical Service Bulletins > Tools - Keyless Entry Transmitter Tester
Keyless Entry Transmitter: Technical Service Bulletins Tools - Keyless Entry Transmitter Tester
File In Section: 9 - Accessories
Bulletin No.: 83-90-12
Date: August, 1998
INFORMATION
Subject: Essential Tool J 43241 Remote Keyless Entry and Passive Keyless Entry Transmitter
Tester
Models:
1990-99 Passenger Cars and Trucks with Remote Keyless Entry or Passive Keyless Entry
Systems
A new essential tool, J 43241 Remote Keyless Entry Transmitter Tester, has been sent to all GM
Dealers. This tester can be used on all RKE and PKE systems, on past as well as current models.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Transmitter > Component Information > Technical Service Bulletins > Tools - Keyless Entry Transmitter Tester > Page 8667
Important:
Before using the tester and the diagnostic chart, the following two steps must be performed.
1. Verify that the keyless entry transmitter is the correct model for the vehicle remote system. An
incorrect model transmitter may pass this test, but may not activate the vehicle remote system. The
correct transmitter can usually be identified by part number.
2. Ensure that the transmitter is synchronized with the vehicle (if applicable). Refer to Transmitter
Synchronization in the appropriate Service Manual.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Remote Keyless Entry <--> [Keyless Entry] > Keyless Entry
Transmitter > Component Information > Technical Service Bulletins > Page 8668
Keyless Entry Transmitter: Service and Repair
1. Reposition rear compartment trim to access the programming connector located at the left of the
rear compartment, for sedan.
2. Remove right back body pillar finish panel to access programming connector, for wagon.
3. Ground the programming connector by connecting the terminals together.
^ The system will verify this has occurred by performing a lock all, unlock drivers door/unlock all,
and trunk/endgate cycle.
4. Press any key on either transmitter.
^ This step programs that particular transmitter to the receiver.
^ The system will verify by performing the same lock/unlock, lock/unlock cycle.
5. The Automatic Door Locking/Unlocking function is automatically enabled for this transmitter. To
leave it enabled, skip to step 6. To disable the
Automatic Door Locking/Unlocking function for this transmitter, perform the following sequence 3
times.
A. Press the door lock button within 1 second of step C the 2nd and 3rd time through this
sequence.
B. Press the door unlock button within 1 second of step A.
C Press the trunk button within 1 second of step B.
^ The receiver will cycle through the lock, unlock, trunk sequence 3 times as verification.
6. To program a second transmitter to the receiver, repeat step 4 with the second transmitter.
Otherwise, go to 7.
7. Disconnect the programming connector.
^ System will not operate if ground connection is not removed.
8. Verify operation of each transmitter.
9. Reposition rear compartment trim, for sedan.
10. Install right back body pillar finish panel, for wagon.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Actuator > Component
Information > Locations > Left Front
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Actuator > Component
Information > Locations > Left Front > Page 8674
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Actuator > Component
Information > Locations > Left Front > Page 8675
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Actuator > Component
Information > Locations > Left Front > Page 8676
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Relay > Component
Information > Locations
Power Door Lock Relay: Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Relay > Component
Information > Locations > Page 8680
Base Of LH A Pillar With Power Door Locks
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Relay > Component
Information > Locations > Page 8681
Power Door Lock Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Switch > Component
Information > Locations > Component Locations
Power Door Lock Switch: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Switch > Component
Information > Locations > Component Locations > Page 8686
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Switch > Component
Information > Locations > Component Locations > Page 8687
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Locks > Power Locks > Power Door Lock Switch > Component
Information > Locations > Page 8688
Power Door Lock Switch RH And LH Front
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Mirrors > Heated Element, Mirror > Component Information > Technical
Service Bulletins > Mirrors - Heated Mirrors, Defrosting Time
Heated Element: Technical Service Bulletins Mirrors - Heated Mirrors, Defrosting Time
INFORMATION
Bulletin No.: 08-08-64-011A
Date: February 25, 2010
Subject: Information on Heated Electrochromatic Outside Rearview Mirror Performance
Models:
2010 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2009 and Prior
HUMMER H2, H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to update the model years. Please discard Corporate
Bulletin Number 08-08-64-011 (Section 08 - Body and Accessories).
Defrosting Time/Performance Concern
The electrochromatic (auto-dimming) outside rearview mirror used on the driver's side of many GM
vehicles is slower to defrost than the passenger side outside rearview mirror.
This is a normal condition. The glass on the driver's side electrochromatic mirror is twice as thick as
the traditional glass on the passenger side mirror. The heating elements for the mirrors on both
sides draw the same wattage, therefore the driver's side mirror will take approximately twice as
long to defrost as the passenger mirror (approximately four minutes versus two minutes). Should a
customer indicate that the driver's side heated mirror is not functioning correctly, verify it's function
based upon this information prior to replacing the mirror.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Mirrors > Memory Positioning Systems > Memory Positioning Module >
Component Information > Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Mirrors > Memory Positioning Systems > Seat Memory Switch >
Component Information > Locations
Seat Memory Switch: Locations
LH Front door on armrest
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Mirrors > Power Mirror Switch > Component Information > Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > Customer Interest: > 05-08-51-008C > Jun > 09 > Body - Bumps or Rust Colored Spots in Paint
Paint: Customer Interest Body - Bumps or Rust Colored Spots in Paint
TECHNICAL
Bulletin No.: 05-08-51-008C
Date: June 22, 2009
Subject: Bumps or Rust Colored Spots in Paint Due to Rail or Iron Dust (Remove Rail Dust)
Models:
1994-2010 GM Passenger Cars and Trucks (Including Saturn) 2003-2010 HUMMER H2
2006-2010 HUMMER H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 05-08-51-008B (Section 08 - Body and Accessories).
Condition
Visible rust colored spots or bumps on a vehicle's paint surface from rail or iron dust.
Cause
Rail dust comes from tiny iron particles produced from the friction between train wheels and the
tracks and gets deposited on the vehicle surfaces. Iron dust can get deposited on the surface if the
vehicle is stored near any operation producing iron dust such as an iron ore yard. Either material
can lay on top of, or become embedded in, the paint surface.
Correction
Because the severity of the condition varies, proper diagnosis of the damage is critical to the
success of repairs. Diagnosis should be performed on horizontal surfaces (hood, roof, deck lid, pick
up box, etc.) after the vehicle has been properly cleaned. There are two types of repair materials
recommended to repair rail dust or iron dust:
1. GEL TYPE OXALIC ACID:
- Has the characteristics of the liquid type oxalic acid but stays where you put it because of its gel
consistency.
2. CLAY TYPE NON-ACID BASED:
- Requires surface lubricant during use. - Has different grades available.
Caution
Rail dust remover (Oxalic Acid) is an acidic substance containing chemicals that will break down
the iron particles embedded in the finish. When working with rail dust remover, use the necessary
safety equipment, including gloves and goggles. Follow the chemical manufacturer's directions
closely because it may require special handling and disposal.
If, upon inspection, some particles are still present, the various chemical manufacturer's processes
can be repeated.
After the removal process, small pits may remain in the clearcoat and can be corrected, in most
cases, with a finesse/polish operation.
Procedure
1. Move the vehicle to a cool shaded area and make sure that the vehicle surfaces are cool during
the removal process. DO NOT PERFORM THE
REMOVAL PROCESS IN DIRECT SUNLIGHT OR ON A VEHICLE WITH HOT OR WARM BODY
PANELS.
2. Wash the vehicle with soap and water. Dry it immediately and clean the affected areas with a
wax and grease remover. 3. Perform the removal process according to the chemical
manufacturer's directions.
Once the damage has been repaired, the final step involves a polishing process.
Rail Dust Remover Manufacturers
Use the chemical manufacturers listed below, or equivalent:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > Customer Interest: > 05-08-51-008C > Jun > 09 > Body - Bumps or Rust Colored Spots in Paint > Page
8713
Auto Magic(R) or Clay Magic(R) products available from:
Auto Wax Company, Inc. 1275 Round Table Dr. Dallas, TX 75247 (800) 826-0828 (Toll-Free) or
(214) 631-4000 (Local) Fax (214) 634-1342 www.automagic.com
[email protected]
E038 Fallout Gel or E038E Liquid Fallout Remover II available from:
Valvoline Car Brite Company 1910 South State Avenue Indianapolis, In 46203 (800) 347-2439 (Toll
Free) or (317) 788-9925 (Local) Fax (317) 788-9930 www.carbrite.com
[email protected] *We
believe these sources and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from these firms or for any such items which may be available from
other sources.
If rail dust remover is not available in your area, call one of the numbers listed above for a
distributor near your location.
Warranty Information (excluding Saab U.S. Models)
Important Refer to the Policy & Procedures Manual, section 1.2.1.7 for detailed information
regarding warranty coverage for this condition.
Important In certain cases where the vehicle finish is severely damaged and the actual repair time
exceeds the published time, the additional time should be submitted in the "Other Labor Hours"
field.
Warranty Information (Saab U.S. Models)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > Customer Interest: > 33-17-01A > Dec > 97 > Exhaust System - Paint Peeling from Painted Muffler
Paint: Customer Interest Exhaust System - Paint Peeling from Painted Muffler
File In Section: 10 - Body
Bulletin No.: 33-17-01A
Date: December, 1997
Subject: Paint Peeling from Muffler (New Repair Paint Available)
Models: 1993-98 Passenger Cars with Painted Mufflers
This bulletin is being revised to add additional model years. Please discard Corporate Bulletin
Number 33-17-01 (Section 10 - Body).
Condition
Some owners may experience paint peeling from the muffler.
Correction
Clean and repaint the affected area using the following procedure and product.
Important:
DO NOT REPLACE COMPONENTS TO REPAIR THIS CONDITION.
The exhaust system must be cold to begin this procedure.
Material Required: * Wabash Products # KB-318-HHHS, available in pints or quarts as ready to
spray material (no mixing required). Call Wabash Products, 1-800-326-7269 or 812-232-6097 for
pricing and shipping information.
Procedure
On a cold exhaust system:
1. Raise vehicle on hoist.
2. While supporting exhaust with a transmission jack, remove the rear exhaust system hangers and
lower the exhaust.
3. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
4. Wire brush the affected area to remove flaking paint and blow off with air.
5. Sand the affected area with # 80 to 150 grit sandpaper to remove rust, dirt or other
contaminants.
6. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
7. Tape off the rear lower body panels and exhaust pipes forward of mufflers to protect from
overspray.
8. Apply paint to affected area in several (6 to 8) thin coats (to prevent sags and runs) obtaining
approximately 1 mil paint coverage.
9. Raise exhaust system with jack, reinstall exhaust hangers, lower vehicle and remove from hoist.
^ Allow 30 minutes drying time.
10. In a well ventilated area, start engine and allow to idle for up to 30 minutes until paint is cured
and dry.
Important:
Some "smoking" will occur while curing the paint with the engine running.
The paint can be heated and cured while driving, but be careful not to get the exhaust system wet
during the first 30 minutes.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > Customer Interest: > 33-17-01A > Dec > 97 > Exhaust System - Paint Peeling from Painted Muffler >
Page 8718
Labor Material
Operation Labor Time Allowance
A6150 0.6 hr - Single Exhaust GC
Add 0.2 hr - Dual Exhaust GC
Important:
While the above procedure and materials are correct for vehicles from 1993 to 1998, the Labor
Operation and Time Allowance only pertains to vehicles in the Warranty period.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 05-08-51-008C > Jun > 09 > Body - Bumps or Rust Colored
Spots in Paint
Paint: All Technical Service Bulletins Body - Bumps or Rust Colored Spots in Paint
TECHNICAL
Bulletin No.: 05-08-51-008C
Date: June 22, 2009
Subject: Bumps or Rust Colored Spots in Paint Due to Rail or Iron Dust (Remove Rail Dust)
Models:
1994-2010 GM Passenger Cars and Trucks (Including Saturn) 2003-2010 HUMMER H2
2006-2010 HUMMER H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 05-08-51-008B (Section 08 - Body and Accessories).
Condition
Visible rust colored spots or bumps on a vehicle's paint surface from rail or iron dust.
Cause
Rail dust comes from tiny iron particles produced from the friction between train wheels and the
tracks and gets deposited on the vehicle surfaces. Iron dust can get deposited on the surface if the
vehicle is stored near any operation producing iron dust such as an iron ore yard. Either material
can lay on top of, or become embedded in, the paint surface.
Correction
Because the severity of the condition varies, proper diagnosis of the damage is critical to the
success of repairs. Diagnosis should be performed on horizontal surfaces (hood, roof, deck lid, pick
up box, etc.) after the vehicle has been properly cleaned. There are two types of repair materials
recommended to repair rail dust or iron dust:
1. GEL TYPE OXALIC ACID:
- Has the characteristics of the liquid type oxalic acid but stays where you put it because of its gel
consistency.
2. CLAY TYPE NON-ACID BASED:
- Requires surface lubricant during use. - Has different grades available.
Caution
Rail dust remover (Oxalic Acid) is an acidic substance containing chemicals that will break down
the iron particles embedded in the finish. When working with rail dust remover, use the necessary
safety equipment, including gloves and goggles. Follow the chemical manufacturer's directions
closely because it may require special handling and disposal.
If, upon inspection, some particles are still present, the various chemical manufacturer's processes
can be repeated.
After the removal process, small pits may remain in the clearcoat and can be corrected, in most
cases, with a finesse/polish operation.
Procedure
1. Move the vehicle to a cool shaded area and make sure that the vehicle surfaces are cool during
the removal process. DO NOT PERFORM THE
REMOVAL PROCESS IN DIRECT SUNLIGHT OR ON A VEHICLE WITH HOT OR WARM BODY
PANELS.
2. Wash the vehicle with soap and water. Dry it immediately and clean the affected areas with a
wax and grease remover. 3. Perform the removal process according to the chemical
manufacturer's directions.
Once the damage has been repaired, the final step involves a polishing process.
Rail Dust Remover Manufacturers
Use the chemical manufacturers listed below, or equivalent:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 05-08-51-008C > Jun > 09 > Body - Bumps or Rust Colored
Spots in Paint > Page 8724
Auto Magic(R) or Clay Magic(R) products available from:
Auto Wax Company, Inc. 1275 Round Table Dr. Dallas, TX 75247 (800) 826-0828 (Toll-Free) or
(214) 631-4000 (Local) Fax (214) 634-1342 www.automagic.com
[email protected]
E038 Fallout Gel or E038E Liquid Fallout Remover II available from:
Valvoline Car Brite Company 1910 South State Avenue Indianapolis, In 46203 (800) 347-2439 (Toll
Free) or (317) 788-9925 (Local) Fax (317) 788-9930 www.carbrite.com
[email protected] *We
believe these sources and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from these firms or for any such items which may be available from
other sources.
If rail dust remover is not available in your area, call one of the numbers listed above for a
distributor near your location.
Warranty Information (excluding Saab U.S. Models)
Important Refer to the Policy & Procedures Manual, section 1.2.1.7 for detailed information
regarding warranty coverage for this condition.
Important In certain cases where the vehicle finish is severely damaged and the actual repair time
exceeds the published time, the additional time should be submitted in the "Other Labor Hours"
field.
Warranty Information (Saab U.S. Models)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 08-08-51-002 > Mar > 08 > Body - TPO Fascia Cleaning Prior
to Painting
Paint: All Technical Service Bulletins Body - TPO Fascia Cleaning Prior to Painting
INFORMATION
Bulletin No.: 08-08-51-002
Date: March 12, 2008
Subject: New Primer For TPO Fascias and Affected Cleaning Process of Painting Operation
Models: 2009 and Prior Passenger Cars and Trucks 2009 and Prior HUMMER H2, H3
The purpose of this bulletin is to inform the technician that General Motors has made a change in
the primer it uses for TPO plastic for service parts. This new primer comes in several different
colors from five different suppliers. This change affects the cleaning process of the painting
operation. The new process is as follows.
1. Wash with soap and water.
2. Clean with a 50% mix of isopropyl alcohol and water (or a waterborne cleaner). Check with your
paint supplier for product recommendations.
3. Scuff sand per your paint suppliers recommendations.
Note:
The use of a solvent-type cleaner will soften, or begin to dissolve the primer. Base coats do not
have any affect on this primer.
4. Reclean with a 50% mix of isopropyl alcohol and water (or a waterborne cleaner).
All fascias, with the exception of the Corvette, Camaro, and Cadillac XLR, are made of TPO. You
may find other TPO parts with this primer. If the technician has a question as to the type of plastic
they are painting, inspect the back of the part for the plastic symbol (TPO).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 33-17-01A > Dec > 97 > Exhaust System - Paint Peeling from
Painted Muffler
Paint: All Technical Service Bulletins Exhaust System - Paint Peeling from Painted Muffler
File In Section: 10 - Body
Bulletin No.: 33-17-01A
Date: December, 1997
Subject: Paint Peeling from Muffler (New Repair Paint Available)
Models: 1993-98 Passenger Cars with Painted Mufflers
This bulletin is being revised to add additional model years. Please discard Corporate Bulletin
Number 33-17-01 (Section 10 - Body).
Condition
Some owners may experience paint peeling from the muffler.
Correction
Clean and repaint the affected area using the following procedure and product.
Important:
DO NOT REPLACE COMPONENTS TO REPAIR THIS CONDITION.
The exhaust system must be cold to begin this procedure.
Material Required: * Wabash Products # KB-318-HHHS, available in pints or quarts as ready to
spray material (no mixing required). Call Wabash Products, 1-800-326-7269 or 812-232-6097 for
pricing and shipping information.
Procedure
On a cold exhaust system:
1. Raise vehicle on hoist.
2. While supporting exhaust with a transmission jack, remove the rear exhaust system hangers and
lower the exhaust.
3. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
4. Wire brush the affected area to remove flaking paint and blow off with air.
5. Sand the affected area with # 80 to 150 grit sandpaper to remove rust, dirt or other
contaminants.
6. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
7. Tape off the rear lower body panels and exhaust pipes forward of mufflers to protect from
overspray.
8. Apply paint to affected area in several (6 to 8) thin coats (to prevent sags and runs) obtaining
approximately 1 mil paint coverage.
9. Raise exhaust system with jack, reinstall exhaust hangers, lower vehicle and remove from hoist.
^ Allow 30 minutes drying time.
10. In a well ventilated area, start engine and allow to idle for up to 30 minutes until paint is cured
and dry.
Important:
Some "smoking" will occur while curing the paint with the engine running.
The paint can be heated and cured while driving, but be careful not to get the exhaust system wet
during the first 30 minutes.
Warranty Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 33-17-01A > Dec > 97 > Exhaust System - Paint Peeling from
Painted Muffler > Page 8733
Labor Material
Operation Labor Time Allowance
A6150 0.6 hr - Single Exhaust GC
Add 0.2 hr - Dual Exhaust GC
Important:
While the above procedure and materials are correct for vehicles from 1993 to 1998, the Labor
Operation and Time Allowance only pertains to vehicles in the Warranty period.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 72-05-11 > Dec > 97 > Warranty - Rail Dust Removal &
Chemical Spotting Labor
Paint: All Technical Service Bulletins Warranty - Rail Dust Removal & Chemical Spotting Labor
File In Section: Warranty Administration
Bulletin No.: 72-05-11
Date: December, 1997
WARRANTY ADMINISTRATION
Subject: Clarification of Rail Dust Removal (A5575-A5580) and Chemical Spotting (A5541-A5544)
Labor Operations
Models: All Past and Future Passenger Cars and Light Duty Trucks
The purpose of this Warranty Administration Bulletin is to clarify the usage, limits and guidelines for
the proper use of the above subject labor operations.
The above subject labor operations were introduced to correct paint imperfections caused by fallout
that occurred either during shipment to the dealer or within the first 12 months or 12,000 miles
(20,000 kms) of vehicle ownership. GM vehicle owners are informed that although no defect in the
factory applied paint causes this, GM will repair, at no charge to the owner, the surfaces of new
vehicles damaged by fallout condition within 12 months or 12,000 miles (20,000 kms) whichever
occurs first. Effective with repair orders dated on or after December 1, 1997, labor operations
A5575-A5580 Rail Dust Removal and A5541 through A5544 Chemical Spotting will be limited to
within the first 12 months or 12,000 miles of the Base Vehicle Warranty (20,000 kms) whichever
occurs first.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 63-17-07B > Jun > 97 > Paint - Basecoat/Clearcoat Paint
Systems Specifications
Paint: All Technical Service Bulletins Paint - Basecoat/Clearcoat Paint Systems Specifications
File In Section: 10 - Body
Bulletin No.: 63-17-07B
Date: June, 1997
INFORMATION
Subject: New Aftermarket Paint Specification (GM4901M) for Basecoat/Clearcoat Paint Systems
(Rigid Exterior Surfaces)
Models: 1993-97 Passenger Cars and Trucks
This bulletin is being revised to provide additional information on approved paint systems
(Attachment 1 added). Please discard Corporate Bulletin Number 63-17-07A (Section 10 - Body).
A vehicle's appearance is important to any customer's perception of that vehicle's quality and
value. Furthermore, when an exterior finish repair is made, the customer expects that repair to
match the showroom finish.
Based upon rigorous and exhaustive testing, General Motors has established an aftermarket
refinish paint specification, known as GM4901M, which is listed in the GM Engineering
Specifications Manual. Use this specification when selecting a paint system for General Motors
vehicle warranty paint repairs. All major paint suppliers are involved and support this program.
The booklet enclosed with Corporate Bulletin # 63-17-07, "GM Approved Refinish Materials", P/N
GM4901 M-D, identifies the paint systems you may use. All approved products (including
VOC-compliant) are listed in the "system" approach recommended by the individual manufacturer.
This booklet will be updated periodically to ensure you are provided with the latest information on
paint systems. GM and Paint Supplier training services encompass this new specification and can
address any questions.
All materials listed in the booklet fall under the current materials allowance. However, this may
change as costs increase.
With this program, it is our goal to ensure quality repairs. After all, skilled technicians using the right
materials offer the only path to true customer enthusiasm. By adhering to the GM4901M
Specification for Aftermarket Paint Repair Materials, you will ensure our customers only receive the
best while maximizing your quality throughout on exterior finish repairs.
When a meeting or training session is held in your area, be sure your team is represented. We look
forward to your support for this program.
Additional Information
In the development of this paint specification, major paint suppliers were invited to submit materials
for approval. The requirements of the program are included in the approved materials booklet
referenced above, dated December, 1996.
Important:
As of 7-1-97, the BASF products listed on Attachment 1 are now approved for use.
The approved suppliers are:
^ Akzo Nobel (Sikkens)
^ American Standox
^ BASF
^ DuPont
^ ICI Autocolor
^ Martin Senour
^ PPG
^ Sherwin Williams
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 63-17-07B > Jun > 97 > Paint - Basecoat/Clearcoat Paint
Systems Specifications > Page 8742
^ Spies Hecker
Your Zone wholesale personnel, Training Centers, STG Field Service Engineers, and the approved
suppliers have additional training materials that may answer your further questions.
Use of these GM approved materials ensures the highest quality for maintaining customer
satisfaction. The dealer or retailer must ensure that all refinish materials, including sublets, meet
GM Specification GM4901-M. Use of materials (and associated application methods) that do not
meet this GM standard may result in a review of claim(s) leading to chargeback(s), as specified in
the Policies and Procedures manual, Article 1.4.17.
The standards will be updated periodically and other suppliers may be added when new standards
are released by the fall of 1997.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 63-17-07B > Jun > 97 > Paint - Basecoat/Clearcoat Paint
Systems Specifications > Page 8743
ATTACHMENT 1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 43-01-03A > Dec > 95 > Paint - Information and SPID Label
Paint: All Technical Service Bulletins Paint - Information and SPID Label
File In Section: 0 - General Information
Bulletin No.: 43-01-03A
Date: December, 1995
INFORMATION
Subject: SPID Label and Paint information
Models: 1995-96 Passenger Cars and Trucks
This bulletin is being revised to add the 1996 model year. Please discard Corporate Bulletin
Number 43-01-03 (Section 0 - General Information).
The information concerns the service parts identification label (SPID) location on all 1995-96
vehicles and the paint information location on those labels.
Important:
There may be a label location change for the F-car (interim 1996-1/2 model year). When the interim
production change occurs, the label may be located on the left door jamb.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 43-01-03A > Dec > 95 > Paint - Information and SPID Label >
Page 8748
1995-96 GENERAL MOTORS Vehicle Paint Identification
SERVICE PARTS IDENTIFICATION
LABEL LOCATIONS
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 43-01-03A > Dec > 95 > Paint - Information and SPID Label >
Page 8749
PAINT CODE EXPLANATIONS
SERVICE PARTS IDENTIFICATION LABEL
The Service Parts Identification Label (below) is a paper material with a protective plastic coating.
It is being used to replace the metal Fisher Body plate. The label should provide the following:
^ Vehicle Identification Number (VIN)
^ "WA" Number
^ Two-Digit Paint Code
^ Paint Technology
^ Vinyl Top Color (where applicable)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 43-01-03A > Dec > 95 > Paint - Information and SPID Label >
Page 8750
^ Interior Color
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 531704 > Sep > 95 > Paint - Polishing And Swirl Mark
Removal
Paint: All Technical Service Bulletins Paint - Polishing And Swirl Mark Removal
File in Section: 10 - Body
Bulletin No. 53-17-04
Date: September, 1995
INFORMATION
Subject: Polishing and Swirl Mark Removal Techniques for Basecoat/Clearcoat Paint
Models: 1993-96 Passenger Cars and Trucks with Basecoat/Clearcoat
This bulletin supersedes and cancels Corporate Bulletin Number 111702. Previous divisional
publication numbers were:
Buick 93-10-22
Cadillac T-93-104
Chevrolet 93-188-OB
GM Canada 93-10-158
Oldsmobile 07-93-106 (Service Guild)
Pontiac 93-10-28
Today's basecoat/clearcoat paint finishes are very different from materials used on vehicles in the
1980's.
Materials, procedures and equipment which once worked well for polishing traditional finishes may
not be acceptable for use on basecoat/clearcoat paint surfaces. The use of outdated materials,
procedures and equipment may produce what appears to be acceptable results under shop
lighting, but will be unacceptable to the owner when the finish is exposed to sunlight (typically, swirl
marks).
While the following information can be most helpful in the new car "prep" area, it should also be
made available to the "used car" area and the collision/ paint repair area.
KEEP THE VEHICLE CLEAN AND DRY;
^ Avoid washing vehicles in direct sunlight.
^ Avoid using strong soaps or chemical detergents.
^ Use "brush less" type automatic car wash equipment.
^ Avoid using products containing acids (unless specified to correct a condition such as "rail dust").
^ Don't use brushes or brooms to remove snow or ice from vehicles in storage or on lots.
^ Cleaning agents and water should be dried promptly and not allowed to dry on the surface.
^ Standing rinse water should be dried promptly and not allowed to dry on the surface.
^ Drying with a soft chamois is recommended.
DON'T CREATE A PROBLEM:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 531704 > Sep > 95 > Paint - Polishing And Swirl Mark
Removal > Page 8755
^ DO NOT polish vehicles unless a surface condition exists that can only be corrected by polishing
(see chart).
^ If a surface condition does exist, the repair approach should be one of "less is best" (the very
least it takes to correct the condition).
^ Avoid removing too much clearcoat (whenever possible, use paint gauges before, during, and
after polishing).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Technical Service Bulletins for Paint: > 531704 > Sep > 95 > Paint - Polishing And Swirl Mark
Removal > Page 8756
^ Use ONLY the products recommended in this bulletin (or their equivalent).
^ Make sure that any power polishing equipment does not exceed the requirements in the polish
manufacturer's recommendation or in the chart.
FINAL STEP:
The final step of the finesse/polish procedure is the removal of SWIRL MARKS. Swirl marks are
defined as very fine scratches in a uniform circular direction that cause an optical distortion on the
paint surface. Swirl marks may not be visible with shop lighting. They should be viewed in direct
sunlight or under specific lights, i.e. Sodium Vapor (parking lot type lights).
SWIRL MARK REMOVAL - To remove swirl marks, use an orbital polisher (DA) with speeds in the
1,500 to 2,000 RPM range. Apply a small amount of the appropriate material (see chart) to the swirl
mark area. Use the pad on the random orbital buffer to spread the material evenly over polished
area before buffing. When buffing, keep pad flat and constantly moving over the repair area. Polish
with heavier pressure applied for 4-6 seconds, then polish with lighter pressure for 6-8 more
seconds. Always blend or feather outer edges of repair spot. After buffing, the buffed areas should
be inspected by the buffing person to ensure that the swirls are completely removed. If swirls are
still present, rebuff as needed. Hand wipe the surface with a clean soft, non-scratching cloth and a
50/50 mixture of Isopropyl Alcohol and water.
^ DON'T USE WAX OR SILICONE-TYPE PRODUCTS TO HIDE SWIRL MARKS (this condition
will reappear later and cause owner dissatisfaction).
^ Specific conditions on paint (environmental damage, rail dust, etc.) can be corrected by referring
to previously published Service bulletins on those specific topics.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By
Various Control Modules
Wiring Harness: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control
Modules
TECHNICAL
Bulletin No.: 09-06-03-004D
Date: December 08, 2010
Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle
Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion
(Disconnect Affected Connector and Apply Dielectric Lubricant)
Models:
2011 and Prior GM Passenger Cars and Trucks
Attention:
This repair can be applied to ANY electrical connection including, but not limited to: lighting, body
electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the
point where it prevents the full engagement of sealed connectors. A light coating on the terminal
surfaces is sufficient to correct the condition.
Supercede: This bulletin is being revised to update the Attention statement and add the 2011
model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System).
Condition
Some customers may comment on any of the following conditions:
- An intermittent no crank/no start
- Intermittent malfunction indicator lamp (MIL) illumination
- Intermittent service lamp illumination
- Intermittent service message(s) being displayed
The technician may determine that he is unable to duplicate the intermittent condition.
Cause
This condition may be caused by a buildup of nonconductive insulating oxidized debris known as
fretting corrosion, occurring between two electrical contact surfaces of the connection or connector.
This may be caused by any of the following conditions:
- Vibration
- Thermal cycling
- Poor connection/terminal retention
- Micro motion
- A connector, component or wiring harness not properly secured resulting in movement
On low current signal circuits this condition may cause high resistance, resulting in intermittent
connections.
On high current power circuits this condition may cause permanent increases in the resistance and
may cause a device to become inoperative.
Representative List of Control Modules and Components
The following is only a representative list of control modules and components that may be affected
by this connection or connector condition and DOES NOT include every possible module or
component for every vehicle.
- Blower Control Module
- Body Control Module (BCM)
- Communication Interface Module (CIM)
- Cooling Fan Control Module
- Electronic Brake Control Module (EBCM)
- Electronic Brake and Traction Control Module (EBTCM)
- Electronic Suspension Control (ESC) Module
- Engine Control Module (ECM)
- Heating, Ventilation and Air Conditioning (HVAC) Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By
Various Control Modules > Page 8762
- HVAC Actuator
- Inflatable Restraint Sensing and Diagnostic Module (SDM)
- Any AIR BAG module
- Seatbelt Lap Anchor Pretensioner
- Seatbelt Retractor Pretensioner
- An SIR system connection or connector condition resulting in the following DTCs being set:
B0015, B0016, B0019, B0020, B0022, or B0023
- Powertrain Control Module (PCM)
- Remote Control Door Lock Receiver (RCDLR)
- Transmission Control Module (TCM)
Correction
Important DO NOT replace the control module, wiring or component for the following conditions:
- The condition is intermittent and cannot be duplicated.
- The condition is present and by disconnecting and reconnecting the connector the condition can
no longer be duplicated.
Use the following procedure to correct the conditions listed above.
1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any
existing history or current DTCs from all of the
control modules (refer to SI).
‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the
connector(s) of the control module/component
which may be causing the condition (refer to SI).
‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control
module/component which may be causing the
condition (refer to SI).
2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component
Connector End Views and Component Locator
documents to locate and disconnect the affected harness connector(s) which are causing the
condition.
Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the
actual electrical contact is being made. In less severe cases it may be unable to be seen or
identified without the use of a magnifying glass.
Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown,
as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush
that is dedicated to the repair of the conditions in this bulletin.
3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side
and the harness side of the affected connector(s).
4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present.
5. Attempt to duplicate the condition by using the following information:
- DTC Diagnostic Procedure
- Circuit/System Description
- Conditions for Running the DTC
- Conditions for Setting the DTC
- Diagnostic Aids
- Circuit/System Verification
‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated,
then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI).
Repair Order Documentation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By
Various Control Modules > Page 8763
Important The following information MUST be documented on the repair order. Failure to do so
may result in a chargeback.
- Customer vehicle condition.
- Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or
Service Message.
- Was a DTC(s) set? If yes, specify which DTC(s) were set.
- After following the procedure contained within this bulletin, could the condition be duplicated?
‹› If the condition was not duplicated, then document the affected module/component connector
name and number on the repair order.
- If the condition was duplicated after the procedure contained within this bulletin was followed, and
additional diagnosis led to the replacement of a module or component, the SI Document ID
Number MUST be written on the repair order.
Parts Information
Alternate Distributor For All of North America
Note
NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada),
specified for use to correct the condition in this bulletin.
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products/materials. General Motors does not endorse, indicate any preference for, or assume
any responsibility for the products or material from this firm or for any such items that may be
available from other sources.
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 09-06-03-004D > Dec > 10 > Electrical - MIL ON/DTC's Set By
Various Control Modules > Page 8764
For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon
the module/component connection that the dielectric lubricant was applied to refer to the table
above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair
Wiring Harness: All Technical Service Bulletins Electrical - Information For Electrical Ground Repair
INFORMATION
Bulletin No.: 10-08-45-001B
Date: October 25, 2010
Subject: Information for Electrical Ground Repair - Use New Replacement Fasteners with
Conductive Finish
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 model year and update the Warranty
Information. Please discard Corporate Bulletin Number 10-08-45-001A (Section 08 - Body and
Accessories).
Electrical Ground Repair Overview
Proper electrical system function relies on secure, stable and corrosion-free electrical ground
connections. Loose, stripped, or corroded connections increase the possibility of improper system
function and loss of module communication. These conditions may also lead to unnecessary
repairs and component replacement.
In general, electrical ground connections are accomplished using one, or a combination of the
following attachment methods:
- Welded M6 stud and nut
- Welded M6 nut and bolt
- Welded M8 nut and bolt
Determine which attachment method is used and perform the appropriate or alternative repair as
described in this bulletin.
M6 Weld Stud Replacement
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. Select a location adjacent the damaged or missing M6 ground stud having 20 mm (0.79 in)
clearance behind the panel surface and 20 mm (0.79 in)
clearance surrounding the M6 conductive rivet stud flange.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
3. Drill a 10 mm (0.40 in) diameter hole through the panel.
4. Remove paint and primer from the area surrounding the 10 mm (0.40 in) hole until bare metal is
visible.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair > Page 8769
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
5. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
6. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
7. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 8. Ensure the rivet stud is securely fastened, WITHOUT ANY detectable movement. 9.
Completely wrap the threads of the rivet stud with painters tape or equivalent.
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the ground wire terminal and conductive nut to maintain a secure, stable and
corrosion-free electrical ground.
10. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 11. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 12. Remove the painters tape or equivalent from the rivet
stud threads. 13. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 14. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair > Page 8770
15. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 16. Install the electrical ground wire terminal to the rivet stud. 17. Select a M6
conductive nut. Refer to the Parts Information section of this bulletin. 18. Install the M6 conductive
nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in).
19. Verify proper system operation.
M6 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M6 weld nut at the electrical ground location is damaged or stripped, a M7 conductive
self-threading bolt may be used to secure the ground
wire terminal.
2. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the weld nut and allow to dry. 3. Remove any loose metal particles from the damaged
or stripped weld nut with a stiff brush. 4. Select a M7 conductive self-threading bolt. Refer to the
Parts Information section of this bulletin 5. Using a small brush, apply Dielectric Lubricant GM P/N
12377900 (Canadian P/N 10953529) to the threads of the M7 conductive self-threading
bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
6. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 7. Install the electrical ground wire terminal to the M7 conductive self-threading bolt.
8. Install the M7 conductive self-threading bolt and:
Tighten Tighten to 9 Nm (80 lb in).
9. Verify proper system operation.
M6 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the electrical ground location is accessible from both sides of the panel, a M6 conductive bolt
and a M6 conductive nut may be used to secure
the electrical ground wire terminal. Refer to the Parts Information section of this bulletin.
2. Select a location adjacent the damaged M6 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 8.5 mm (0.33 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 8.5 mm (0.33 in) hole until bare metal is visible. 6. Select a M6 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M6 conductive bolt to the ground
location.
10. Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M6 conductive nut to the bolt and:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair > Page 8771
Tighten Tighten to 8 Nm (71 lb in).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is accessible from both sides of the panel, a M8
conductive bolt and a M8 conductive nut may be
used to secure the electrical ground wire terminal. Refer to the Parts Information section of this
bulletin.
2. Select a location adjacent the M8 weld nut having 20 mm (0.79 in) clearance behind the panel
surface and 20 mm (0.79 in) clearance surrounding
the new electrical ground site.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the surface
surrounding the ground location and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel. 5. Remove paint and primer from the
area surrounding the 10 mm (0.40 in) hole until bare metal is visible. 6. Select a M8 conductive
bolt. Refer to the Parts Information section of this bulletin. 7. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M8 conductive bolt.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
8. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 9. Install the electrical ground wire terminal and the M8 conductive bolt to the ground
location.
10. Select a M8 conductive nut. Refer to the Parts Information section of this bulletin. 11. Install the
M8 conductive nut to the bolt and:
Tighten Tighten to 22 Nm (16 lb ft).
Note The repair area MUST BE properly refinished to maintain a secure, stable and corrosion-free
electrical ground.
12. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 13. Verify proper system operation.
M8 Weld Nut Alternative Repair
Caution
Use only the GM-approved replacement fasteners with conductive finish for electrical ground
repair.
1. If the M8 weld nut electrical ground location is not accessible from both sides of the panel, a M6
conductive rivet stud and a M6 conductive nut
may be used to secure the electrical ground wire terminal.
2. Select a location adjacent the damaged M8 weld nut having 20 mm (0.79 in) clearance behind
the panel surface and 20 mm (0.79 in) clearance
surrounding the M6 conductive rivet stud flange.
3. Using GM approved residue-free solvent or equivalent, remove any grease from the repair site
and allow to dry.
Note Ensure 20 mm (0.79 in) clearance is maintained behind the panel to be drilled.
4. Drill a 10 mm (0.40 in) diameter hole through the panel.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair > Page 8772
5. Remove paint and primer from the area surrounding the 10 mm (0.40 in) until bare metal is
visible.
Important The M6 conductive rivet stud as shown, can accommodate a panel thickness range of
0.7-4.2 mm (0.03-0.17 in). If there are layers of sheet metal, they should be touching without any
air gaps to ensure a good ground.
6. Select a M6 conductive rivet stud. Refer to the Parts Information section of this bulletin.
Note Use the GE-50317 rivet stud tool kit.
7. Place the M6 conductive rivet stud (1) in the 10 mm (0.40 in) hole. Assemble the rivet stud tool
(2) with the groove and flare side facing the rivet
stud, then the washer and the M6 nut (3).
8. Using a wrench on the rivet stud tool, and a socket on the M6 nut, secure the M6 conductive
rivet stud. 9. Ensure the new rivet stud is securely fastened, WITHOUT ANY detectable movement.
10. Completely wrap the threads of the rivet stud with painters tape or equivalent.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair > Page 8773
Note The rivet stud and surrounding panel area MUST BE properly refinished PRIOR to the
installation of the electrical ground wire terminal and conductive nut to maintain a secure, stable
and corrosion-free electrical ground.
11. Refinish the repair area using an anti-corrosion primer. Refer to Anti-Corrosion Treatment and
Repair in SI. 12. Allow the refinished repair area to cure sufficiently before removing the protective
material applied to the rivet stud threads. 13. Remove the painters tape or equivalent from the rivet
stud threads. 14. Using GM approved residue-free solvent or equivalent, thoroughly clean the rivet
stud threads to remove any adhesive and allow to dry. 15. Using a small brush, apply Dielectric
Lubricant GM P/N 12377900 (Canadian P/N 10953529) to the threads of the M6 conductive rivet
stud.
Note Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is
a small motion between electrical contacts. The oxidized wear debris can accumulate at the
electrical contact points causing the electrical resistance across the connection to increase.
16. Carefully remove ANY corrosion or contamination that may be present on the electrical ground
wire terminal. 17. Install the electrical ground wire terminal to the M6 conductive rivet stud. 18.
Select a M6 conductive nut. Refer to the Parts Information section of this bulletin. 19. Install the M6
conductive nut to the rivet stud and:
Tighten Tighten to 8 Nm (71 lb in)
20. Verify proper system operation.
Parts Information
Warranty Information (excluding Saab Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 10-08-45-001B > Oct > 10 > Electrical - Information For Electrical
Ground Repair > Page 8774
For vehicles repaired under warranty, use the table.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 06-08-45-004 > May > 06 > Electrical - Instrument Panel &
General Wiring Repair
Wiring Harness: All Technical Service Bulletins Electrical - Instrument Panel & General Wiring
Repair
Bulletin No.: 06-08-45-004
Date: May 02, 2006
INFORMATION
Subject: Instrument Panel (I/P), Body and General Wiring Harness Repair
Models: 2007 and Prior GM Cars and Trucks 2003-2007 HUMMER H2 2006-2007 HUMMER H3
Important:
A part restriction has been implemented on all Body and I/P harnesses and is being administered
by the PQC. If a body or I/P harness replacement is required, it can take 12-28 weeks for a
harness to be built and delivered to a dealer. The dealer technician is expected to repair any
harness damage as the first and best choice before replacing a harness.
In an effort to standardize repair practices, General Motors is requiring that all wiring harnesses be
repaired instead of replaced. If there is a question concerning which connector and/or terminal you
are working on, refer to the information in the appropriate Connector End Views in SI. The
Instruction Manual J 38125-620, which is sent with each new update of the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal remove information.
Important:
There are some parts in the J 38125 Terminal Repair Kit (i.e. SIR connector CPAs and heat shrink
tube (used in high heat area pigtail replacement) and some TPAs that are not available from
GMSPO. It is vitally important that each update to the J 38125 Terminal Repair Kit be done as soon
as it arrives at the dealer.
Utilize the Terminal Repair Kit (J 38125) to achieve an effective wiring repair. The Terminal Repair
Kit has been an essential tool for all GM Dealers since 1987. Replacement terminals and tools for
this kit are available through SPX/Kent Moore. Refer to Corporate Bulletin Number 06-08-45-001
for more information.
The Instruction Manual J 38125-620, which is sent with each new update to the J 38125 Terminal
Repair Kit, also has terminal crimping and terminal removal information.
U.S. Dealers Only - Training courses (including Tech Assists, Emerging Issues, Web, IDL and
Hands-on) are available through the GM Training website. Refer to Resources and then Training
Materials for a complete list of available courses.
Canadian Dealers Only - Refer to the Training section of GM infoNet for a complete list of available
courses and a copy of the J 38125 Terminal Repair Kit Instruction Manual.
Wiring repair information is also available in Service Information (SI). The Wiring Repair section
contains information for the following types of wiring repairs:
- Testing for intermittent conditions and poor conditions
- Flat wire repairs
- GMLAN wiring repairs
- High temperature wiring repairs
- Splicing copper wire using splice clips
- Splicing copper wire using splice sleeves
- Splicing twisted or shielded cable
- Splicing inline harness diodes
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > 06-08-45-004 > May > 06 > Electrical - Instrument Panel &
General Wiring Repair > Page 8779
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8780
Paint: By Symptom
Technical Service Bulletin # 05-08-51-008C Date: 090622
Body - Bumps or Rust Colored Spots in Paint
TECHNICAL
Bulletin No.: 05-08-51-008C
Date: June 22, 2009
Subject: Bumps or Rust Colored Spots in Paint Due to Rail or Iron Dust (Remove Rail Dust)
Models:
1994-2010 GM Passenger Cars and Trucks (Including Saturn) 2003-2010 HUMMER H2
2006-2010 HUMMER H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 05-08-51-008B (Section 08 - Body and Accessories).
Condition
Visible rust colored spots or bumps on a vehicle's paint surface from rail or iron dust.
Cause
Rail dust comes from tiny iron particles produced from the friction between train wheels and the
tracks and gets deposited on the vehicle surfaces. Iron dust can get deposited on the surface if the
vehicle is stored near any operation producing iron dust such as an iron ore yard. Either material
can lay on top of, or become embedded in, the paint surface.
Correction
Because the severity of the condition varies, proper diagnosis of the damage is critical to the
success of repairs. Diagnosis should be performed on horizontal surfaces (hood, roof, deck lid, pick
up box, etc.) after the vehicle has been properly cleaned. There are two types of repair materials
recommended to repair rail dust or iron dust:
1. GEL TYPE OXALIC ACID:
- Has the characteristics of the liquid type oxalic acid but stays where you put it because of its gel
consistency.
2. CLAY TYPE NON-ACID BASED:
- Requires surface lubricant during use. - Has different grades available.
Caution
Rail dust remover (Oxalic Acid) is an acidic substance containing chemicals that will break down
the iron particles embedded in the finish. When working with rail dust remover, use the necessary
safety equipment, including gloves and goggles. Follow the chemical manufacturer's directions
closely because it may require special handling and disposal.
If, upon inspection, some particles are still present, the various chemical manufacturer's processes
can be repeated.
After the removal process, small pits may remain in the clearcoat and can be corrected, in most
cases, with a finesse/polish operation.
Procedure
1. Move the vehicle to a cool shaded area and make sure that the vehicle surfaces are cool during
the removal process. DO NOT PERFORM THE
REMOVAL PROCESS IN DIRECT SUNLIGHT OR ON A VEHICLE WITH HOT OR WARM BODY
PANELS.
2. Wash the vehicle with soap and water. Dry it immediately and clean the affected areas with a
wax and grease remover. 3. Perform the removal process according to the chemical
manufacturer's directions.
Once the damage has been repaired, the final step involves a polishing process.
Rail Dust Remover Manufacturers
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8781
Use the chemical manufacturers listed below, or equivalent:
Auto Magic(R) or Clay Magic(R) products available from:
Auto Wax Company, Inc. 1275 Round Table Dr. Dallas, TX 75247 (800) 826-0828 (Toll-Free) or
(214) 631-4000 (Local) Fax (214) 634-1342 www.automagic.com
[email protected]
E038 Fallout Gel or E038E Liquid Fallout Remover II available from:
Valvoline Car Brite Company 1910 South State Avenue Indianapolis, In 46203 (800) 347-2439 (Toll
Free) or (317) 788-9925 (Local) Fax (317) 788-9930 www.carbrite.com
[email protected] *We
believe these sources and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from these firms or for any such items which may be available from
other sources.
If rail dust remover is not available in your area, call one of the numbers listed above for a
distributor near your location.
Warranty Information (excluding Saab U.S. Models)
Important Refer to the Policy & Procedures Manual, section 1.2.1.7 for detailed information
regarding warranty coverage for this condition.
Important In certain cases where the vehicle finish is severely damaged and the actual repair time
exceeds the published time, the additional time should be submitted in the "Other Labor Hours"
field.
Warranty Information (Saab U.S. Models)
Disclaimer
Technical Service Bulletin # 33-17-01A Date: 971201
Exhaust System - Paint Peeling from Painted Muffler
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8782
File In Section: 10 - Body
Bulletin No.: 33-17-01A
Date: December, 1997
Subject: Paint Peeling from Muffler (New Repair Paint Available)
Models: 1993-98 Passenger Cars with Painted Mufflers
This bulletin is being revised to add additional model years. Please discard Corporate Bulletin
Number 33-17-01 (Section 10 - Body).
Condition
Some owners may experience paint peeling from the muffler.
Correction
Clean and repaint the affected area using the following procedure and product.
Important:
DO NOT REPLACE COMPONENTS TO REPAIR THIS CONDITION.
The exhaust system must be cold to begin this procedure.
Material Required: * Wabash Products # KB-318-HHHS, available in pints or quarts as ready to
spray material (no mixing required). Call Wabash Products, 1-800-326-7269 or 812-232-6097 for
pricing and shipping information.
Procedure
On a cold exhaust system:
1. Raise vehicle on hoist.
2. While supporting exhaust with a transmission jack, remove the rear exhaust system hangers and
lower the exhaust.
3. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
4. Wire brush the affected area to remove flaking paint and blow off with air.
5. Sand the affected area with # 80 to 150 grit sandpaper to remove rust, dirt or other
contaminants.
6. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
7. Tape off the rear lower body panels and exhaust pipes forward of mufflers to protect from
overspray.
8. Apply paint to affected area in several (6 to 8) thin coats (to prevent sags and runs) obtaining
approximately 1 mil paint coverage.
9. Raise exhaust system with jack, reinstall exhaust hangers, lower vehicle and remove from hoist.
^ Allow 30 minutes drying time.
10. In a well ventilated area, start engine and allow to idle for up to 30 minutes until paint is cured
and dry.
Important:
Some "smoking" will occur while curing the paint with the engine running.
The paint can be heated and cured while driving, but be careful not to get the exhaust system wet
during the first 30 minutes.
Warranty Information
Labor Material
Operation Labor Time Allowance
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8783
A6150 0.6 hr - Single Exhaust GC
Add 0.2 hr - Dual Exhaust GC
Important:
While the above procedure and materials are correct for vehicles from 1993 to 1998, the Labor
Operation and Time Allowance only pertains to vehicles in the Warranty period.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Technical Service Bulletin # 05-08-51-008C Date: 090622
Body - Bumps or Rust Colored Spots in Paint
TECHNICAL
Bulletin No.: 05-08-51-008C
Date: June 22, 2009
Subject: Bumps or Rust Colored Spots in Paint Due to Rail or Iron Dust (Remove Rail Dust)
Models:
1994-2010 GM Passenger Cars and Trucks (Including Saturn) 2003-2010 HUMMER H2
2006-2010 HUMMER H3 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 05-08-51-008B (Section 08 - Body and Accessories).
Condition
Visible rust colored spots or bumps on a vehicle's paint surface from rail or iron dust.
Cause
Rail dust comes from tiny iron particles produced from the friction between train wheels and the
tracks and gets deposited on the vehicle surfaces. Iron dust can get deposited on the surface if the
vehicle is stored near any operation producing iron dust such as an iron ore yard. Either material
can lay on top of, or become embedded in, the paint surface.
Correction
Because the severity of the condition varies, proper diagnosis of the damage is critical to the
success of repairs. Diagnosis should be performed on horizontal surfaces (hood, roof, deck lid, pick
up box, etc.) after the vehicle has been properly cleaned. There are two types of repair materials
recommended to repair rail dust or iron dust:
1. GEL TYPE OXALIC ACID:
- Has the characteristics of the liquid type oxalic acid but stays where you put it because of its gel
consistency.
2. CLAY TYPE NON-ACID BASED:
- Requires surface lubricant during use. - Has different grades available.
Caution
Rail dust remover (Oxalic Acid) is an acidic substance containing chemicals that will break down
the iron particles embedded in the finish. When working with rail dust remover, use the necessary
safety equipment, including gloves and goggles. Follow the chemical manufacturer's directions
closely because it may require special handling and disposal.
If, upon inspection, some particles are still present, the various chemical manufacturer's processes
can be repeated.
After the removal process, small pits may remain in the clearcoat and can be corrected, in most
cases, with a finesse/polish operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8784
Procedure
1. Move the vehicle to a cool shaded area and make sure that the vehicle surfaces are cool during
the removal process. DO NOT PERFORM THE
REMOVAL PROCESS IN DIRECT SUNLIGHT OR ON A VEHICLE WITH HOT OR WARM BODY
PANELS.
2. Wash the vehicle with soap and water. Dry it immediately and clean the affected areas with a
wax and grease remover. 3. Perform the removal process according to the chemical
manufacturer's directions.
Once the damage has been repaired, the final step involves a polishing process.
Rail Dust Remover Manufacturers
Use the chemical manufacturers listed below, or equivalent:
Auto Magic(R) or Clay Magic(R) products available from:
Auto Wax Company, Inc. 1275 Round Table Dr. Dallas, TX 75247 (800) 826-0828 (Toll-Free) or
(214) 631-4000 (Local) Fax (214) 634-1342 www.automagic.com
[email protected]
E038 Fallout Gel or E038E Liquid Fallout Remover II available from:
Valvoline Car Brite Company 1910 South State Avenue Indianapolis, In 46203 (800) 347-2439 (Toll
Free) or (317) 788-9925 (Local) Fax (317) 788-9930 www.carbrite.com
[email protected] *We
believe these sources and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from these firms or for any such items which may be available from
other sources.
If rail dust remover is not available in your area, call one of the numbers listed above for a
distributor near your location.
Warranty Information (excluding Saab U.S. Models)
Important Refer to the Policy & Procedures Manual, section 1.2.1.7 for detailed information
regarding warranty coverage for this condition.
Important In certain cases where the vehicle finish is severely damaged and the actual repair time
exceeds the published time, the additional time should be submitted in the "Other Labor Hours"
field.
Warranty Information (Saab U.S. Models)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8785
Disclaimer
Technical Service Bulletin # 33-17-01A Date: 971201
Exhaust System - Paint Peeling from Painted Muffler
File In Section: 10 - Body
Bulletin No.: 33-17-01A
Date: December, 1997
Subject: Paint Peeling from Muffler (New Repair Paint Available)
Models: 1993-98 Passenger Cars with Painted Mufflers
This bulletin is being revised to add additional model years. Please discard Corporate Bulletin
Number 33-17-01 (Section 10 - Body).
Condition
Some owners may experience paint peeling from the muffler.
Correction
Clean and repaint the affected area using the following procedure and product.
Important:
DO NOT REPLACE COMPONENTS TO REPAIR THIS CONDITION.
The exhaust system must be cold to begin this procedure.
Material Required: * Wabash Products # KB-318-HHHS, available in pints or quarts as ready to
spray material (no mixing required). Call Wabash Products, 1-800-326-7269 or 812-232-6097 for
pricing and shipping information.
Procedure
On a cold exhaust system:
1. Raise vehicle on hoist.
2. While supporting exhaust with a transmission jack, remove the rear exhaust system hangers and
lower the exhaust.
3. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
4. Wire brush the affected area to remove flaking paint and blow off with air.
5. Sand the affected area with # 80 to 150 grit sandpaper to remove rust, dirt or other
contaminants.
6. Clean the affected area with a wax and grease remover, lacquer thinner or other suitable
solvent.
7. Tape off the rear lower body panels and exhaust pipes forward of mufflers to protect from
overspray.
8. Apply paint to affected area in several (6 to 8) thin coats (to prevent sags and runs) obtaining
approximately 1 mil paint coverage.
9. Raise exhaust system with jack, reinstall exhaust hangers, lower vehicle and remove from hoist.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Paint, Striping and Decals > Paint > System Information > Technical
Service Bulletins > All Other Service Bulletins for Paint: > Page 8786
^ Allow 30 minutes drying time.
10. In a well ventilated area, start engine and allow to idle for up to 30 minutes until paint is cured
and dry.
Important:
Some "smoking" will occur while curing the paint with the engine running.
The paint can be heated and cured while driving, but be careful not to get the exhaust system wet
during the first 30 minutes.
Warranty Information
Labor Material
Operation Labor Time Allowance
A6150 0.6 hr - Single Exhaust GC
Add 0.2 hr - Dual Exhaust GC
Important:
While the above procedure and materials are correct for vehicles from 1993 to 1998, the Labor
Operation and Time Allowance only pertains to vehicles in the Warranty period.
* We believe this source and their equipment to be reliable. There may be additional manufacturers
of such equipment. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products or equipment from these firms or for any such items which may be
available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Memory Positioning Module >
Component Information > Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Power Door Lock Relay >
Component Information > Locations
Power Door Lock Relay: Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Power Door Lock Relay >
Component Information > Locations > Page 8794
Base Of LH A Pillar With Power Door Locks
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Power Door Lock Relay >
Component Information > Locations > Page 8795
Power Door Lock Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Power Seat Control Module >
Component Information > Locations > Driver Seat Adjuster Memory Module
Power Seat Control Module: Locations Driver Seat Adjuster Memory Module
Below Center Of Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Power Seat Control Module >
Component Information > Locations > Driver Seat Adjuster Memory Module > Page 8800
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Seat Heater Control Module >
Component Information > Locations > Driver Seat Heater Control Module
Seat Heater Control Module: Locations Driver Seat Heater Control Module
Attached to seat support, under LH Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Seat Heater Control Module >
Component Information > Locations > Driver Seat Heater Control Module > Page 8805
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Relays and Modules - Body and Frame > Trunk / Liftgate Relay >
Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Head Restraint System > System Information > Technical
Service Bulletins > Restraints - Driver/Passenger Seat Head Rest Information
Head Restraint System: Technical Service Bulletins Restraints - Driver/Passenger Seat Head Rest
Information
INFORMATION
Bulletin No.: 10-08-50-003A
Date: March 24, 2011
Subject: Information on Driver or Passenger Seat Head Restraint Concerns with Comfort, Custom
Upholstery or Other Comfort Enhancing Devices
Models:
2012 and Prior GM Passenger Cars and Trucks Equipped with Adjustable Head Restraints
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 10-08-50-003 (Section 08 - Body and Accessories).
Important ON A GM VEHICLE EQUIPPED WITH ADJUSTABLE HEAD RESTRAINTS, USE THE
HEAD RESTRAINT COVERS, FOAM AND OTHER SEAT-RELATED EQUIPMENT AS
RELEASED BY GM FOR THAT VEHICLE. DO NOT ALTER OR REPOSITION THE HEAD
RESTRAINT SYSTEM. ANY ALTERATIONS TO HEAD RESTRAINTS DEFEATS THE INTENDED
DESIGN OF THE SYSTEM. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE
OF SUCH IMPROPER DESIGN ALTERATIONS, INCLUDING ANY WARRANTY REPAIRS
INCURRED.
You may have a customer with a concern that the head restraint is uncomfortable or sits too far
forward. The front driver and passenger seats are equipped with head restraints that have been
designed to help minimize injuries while still providing comfort to the occupants. Each GM vehicle
has its own specifically designed head restraint.
The head restraints should only be used in the vehicle for which they were designed. The head
restraint will not operate to its design intent if the original foam is replaced (1) by non-GM foam or
head restraint, (2) by GM foam or head restraint designed for a different vehicle, (3) by GM foam or
head restraint that has been altered by a trim shop or (4) if any object, such as an aftermarket
comfort enhancing pad or device, is installed.
Never modify the design of the head restraint or remove the head restraint from the vehicle as this
may interfere with the operation of the seating and restraint systems and may prevent proper
positioning of the passenger within the vehicle.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Memory Positioning Systems > Memory Positioning Module >
Component Information > Locations
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Memory Positioning Systems > Seat Memory Switch >
Component Information > Locations
Seat Memory Switch: Locations
LH Front door on armrest
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Control Module > Component Information >
Locations > Driver Seat Adjuster Memory Module
Power Seat Control Module: Locations Driver Seat Adjuster Memory Module
Below Center Of Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Control Module > Component Information >
Locations > Driver Seat Adjuster Memory Module > Page 8825
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor
Power Seat Motor: Locations Driver FWD/Back Motor
Under Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor > Page 8830
Power Seat Motor: Locations Driver Height Seat Motor
Front
Under Driver Seat
Rear
Under Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor > Page 8831
Power Seat Motor: Locations Driver Seatback Lumbar Support Motor
Part of Driver Seat bottom
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor > Page 8832
Power Seat Motor: Locations Passenger FWD/Back Motor
Under Passenger Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor > Page 8833
Power Seat Motor: Locations
Driver FWD/Back Motor
Under Driver Seat
Front
Under Driver Seat
Rear
Under Driver Seat
Driver Seatback Lumbar Support Motor
Part of Driver Seat bottom
Passenger FWD/Back Motor
Under Passenger Seat
Front
Under Passenger Seat
Rear
Under Passenger Seat
Passenger Seatback Lumbar Support Motor
Part of Passenger Seat bottom
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor > Page 8834
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Motor > Component Information > Locations >
Driver FWD/Back Motor > Page 8835
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Switch > Component Information > Locations >
Component Locations
Power Seat Switch: Component Locations
Driver Seat Switch Pod
Bottom Of driver Seat, outboard Side
Passenger Seat Switch Pod
Part of bottom Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Switch > Component Information > Locations >
Component Locations > Page 8840
Power Seat Switch: Connector Locations
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Switch > Component Information > Locations >
Component Locations > Page 8841
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Switch > Component Information > Diagrams > LH
and RH Lumbar Switch Assembly
C312 & C313: LH And RH Lumbar Switch Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Power Seat Switch > Component Information > Diagrams > LH
and RH Lumbar Switch Assembly > Page 8844
Power Seat Switch LH And RH
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info
Seat Cover: Technical Service Bulletins Interior - Seat Cover Wrinkle/Crease/Burn Info
INFORMATION
Bulletin No.: 04-08-50-006D
Date: September 09, 2010
Subject: Minor Wrinkles/Creases, Discoloration, Cigarette Burns and Customer Induced Cuts and
Stains on Front and Rear Driver and Passenger Seats with Leather, Vinyl or Cloth Seat Covers
Models:
2011 and Prior GM Passenger Cars and Light Duty Trucks 2009 and Prior HUMMER H2 2010 and
Prior HUMMER H3 2009 and Prior Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add a model year. Please discard Corporate Bulletin
Number 04-08-50-006C (Section 08 - Body and Accessories).
If a customer comes in to your dealership due to certain conditions of the seat covers (splits,
wrinkles, loose stitching, etc.), you must examine the seat cover in order to determine the validity of
the customer claim. Some components from the above listed vehicles have been returned to the
Warranty Parts Center (WPC) and analysis of these parts showed "customer induced damage" or
No Trouble Found (NTF).
The dealer should pay particular attention to the following conditions:
- Cigarette burns
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info > Page 8849
- Customer induced cuts (knife cuts, cut by customer tools, etc.)
- Paint stains (customer should have cleaned paint stains while paint was still wet)
- Coffee stains and other removable dirt These should be cleaned as described in the Owner's
Manual under Appearance Care. Also, refer to Corporate Bulletin Number 06-00-89-029A or later.
- Evidence of chemicals used for cleaning, other than those specified in the Owner's Manual
- Other chemical spills
- Minor and normal leather wrinkles as a result of use
- Other defects to the seat cover not detected during the pre-delivery inspection (PDI).
Inform the customer that the above issues were not present when the vehicle was purchased and
cannot be replaced under warranty. The covers, however, may be repaired or replaced at the
customer's expense.
The following conditions are not caused by the customer and should be covered by warranty:
- Split seams
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info > Page 8850
- Wear/cracking/peeling
- Discoloration/dye transfer from customer clothing (if discoloration/dye transfer is not removed
after using GM Leather and Vinyl Plastic Cleaner, P/N 88861401 (in Canada, P/N 88861409),
replace the covers.)
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info > Page 8851
Seat Cover: Technical Service Bulletins Interior - Elimination Of Unwanted Odors
INFORMATION
Bulletin No.: 00-00-89-027E
Date: September 29, 2008
Subject: Eliminating Unwanted Odors in Vehicles
Models: 2009 and Prior GM Passenger Cars and Trucks (including Saturn) 2009 and Prior
HUMMER H2, H3 Vehicles 2009 and Prior Saab 9-7X
Supercede:
This bulletin is being revised to add model years and refine the instructions. Please discard
Corporate Bulletin Number 00-00-89-027D (Section 00 - General Information).
Vehicle Odor Elimination
General Motors offers a product that may control or eliminate odors in the interior and luggage
compartment areas of GM vehicles. GM Vehicle Care Odor Eliminator is a non-toxic,
biodegradable odor remover. This odorless product has been shown to greatly reduce or remove
objectionable smells of mold and mildew resulting from vehicle water leaks (as well as customer
created odors, i.e. smoke). You may use GM Vehicle Care Odor Eliminator on fabrics, vinyl,
leather, carpet and sound deadening materials. It may also be induced into HVAC modules and
instrument panel ducts (for the control of non-bacterial related odors).
Important:
This product leaves no residual scent and should not be sold as or considered an air freshener.
Product action may result in the permanent elimination of an odor and may be preferable to
customers with allergies who are sensitive to perfumes.
How to Use This Product
GM Vehicle Care Odor Eliminator may be sprayed on in a ready-to-use formula or used in steam
cleaners as an additive with carpet shampoo. This water-based, odorless product is safe for all
vehicle interiors. Do not wet or soak any interior surface that plain water would cause to
deteriorate, as this product will have the same effect. Also avoid letting this product come into
contact with vinegar or any acidic substance. Acid-based products will hamper the effectiveness of,
or render GM Vehicle Care Odor Eliminator inert.
Note:
Complete eight page treatment sheets are enclosed within each case of GM Vehicle Care Odor
Eliminator. These treatment instructions range from simple vehicle odor elimination to full step by
step procedures for odor removal from water leaks. If lost, contact 800-977-4145 to get a
replacement set faxed or e-mailed to your dealership.
Instructions and cautions are printed on the bottle, but additional help is available. If you encounter
a difficult to eliminate or reoccurring odor, you may call 1-800-955-8591 (in Canada,
1-800-977-4145) to obtain additional information and usage suggestions.
Important:
This product may effectively remove odors when directly contacting the odor source. It should be
used in conjunction with diagnostic procedures (in cases such as a water leak) to first eliminate the
root cause of the odor, and then the residual odor to permanently correct the vehicle condition.
Vehicle Waterleak Odor Elimination
STEP ONE:
Confirm that all water leaks have been repaired. Determine what areas of the vehicle were water
soaked or wet. Components with visible mold/mildew staining should be replaced. Isolate the odor
source inside the vehicle. Often an odor can be isolated to an area or component of the vehicle
interior by careful evaluation. Odor evaluation may need to be performed by multiple persons.
Another method of isolating an odor source is to remove and segregate interior trim and
components. Plastic sheeting or drop cloths can be used to confine seats, headliners, etc. to assist
in evaluation and diagnoses. If appropriate the vehicle and interior trim should be evaluated
separately to determine if the odor stays with the vehicle or the interior components. Odors that
stay with the vehicle may be isolated to insulating and sound deadening materials (i.e. water leak
at the windshield or standing water in the front foot well area caused mold/mildew to form on the
bulkhead or kick panel sound deadening pads. If the interior is removed the floor pan and
primed/painted surfaces should be treated with bleach/soap solution, rinsed with clean water and
dried. Interior surfaces should then be treated with GM Vehicle Care Odor Eliminator product
before reinstalling carpet or reassembling.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info > Page 8852
The GM Vehicle Care Odor Eliminator product is an effective odor elimination product when used
properly. It must come into direct contact with the odor source. It should be used in conjunction with
diagnostic procedures to first eliminate the root cause of the odor. Some procedures for use after
odor root cause correction are:
STEP TWO:
^ Use the trigger spray head.
^ Put a drop of dish soap the size of a quarter in the bottom of a bottle.
^ Add 8 oz. of GM Vehicle Care Odor Eliminator (1 cup) to the dish soap and top off the bottle with
tap water.
^ This formula should be used on hard surfaces (dash, interior plastic molding, and floor pan)
STEP THREE:
The third step to neutralizing the vehicle is a light to medium treatment of all carpeting and
upholstered seats with the GM Vehicle Care Odor Eliminator formula and a wide fan spray setting
(at full strength) (i.e.: carpeting on the driver's side requires 4-5 triggers pulls for coverage). The
headliner and trunk should be sprayed next. Lightly brushing the formula into the carpeting and
upholstery is a recommended step for deep odor problems. The dash and all hard surfaces should
be sprayed with dish soap/water mixture. Let stand for 1-2 minutes then wipe off the surface.
STEP FOUR: (vehicle ventilation system treatment)
The ventilation system is generally the last step in the treatment of the vehicle.
a. Spray the GM Vehicle Care Odor Eliminator formula into all dash vents. (1-2 trigger pulls per
vent).
b. Start the vehicle and turn the vehicle fan on high cool (not A/C setting).
c. Spray the formula (10 trigger pulls) into the outside fresh air intake vent (cowl at base of
windshield)
d. Enter the vehicle after 1 minute and wipe off the excess formula spurting out of the dash vents.
e. Smell the air coming from the dash vents. If odors are still present, spray another 5 triggers into
the cowl, wait another minute and smell the results. Once you have obtained a fresh, clean smell
coming from the vents, turn the system to the A/C re-circulation setting. Roll up the windows, spray
3-5 pumps into the right lower IP area and let the vehicle run with the fan set on high for 5-7
minutes.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited
is resolved without completing every step, the remaining steps do not need to be performed. If
these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
Additional Suggestions to Increase Customer Satisfaction
Here are some additional ideas to benefit your dealership and to generate greater customer
enthusiasm for this product.
^ Keep this product on-hand for both the Service Department and the Used Car lot. Add value to
your used car trades; treat loaner and demo cars during service and at final sale to eliminate
smoke, pet, and other common odors offensive to customers. Make deodorizing a vehicle part of
your normal vehicle detailing service.
^ Consider including GM Vehicle Care Odor Eliminator as a give-away item with new vehicle
purchases. Many dealers give away as "gifts" various cleaning supplies at time of delivery. GM
Odor Eliminator is one of a few products GM offers that has as many uses in the home as in the
vehicle. Customers may find this product can be used for a host of recreational activities
associated with their new vehicle, such as deodorizing a boat they tow, or a camper.
^ GM Odor Eliminator and many of the GM Vehicle Care products offer you the chance to increase
dealership traffic as these superior quality products cannot be purchased in stores. Many
Dealerships have product displays at the parts counter. Consider additional displays in the
Customer Service Lounge, the Showroom and at the Service Desk or Cashier Window. Many
customers who purchase vehicles and receive regular maintenance at your dealership may never
visit the parts counter, and subsequently are not exposed to the variety and value that these
products offer.
Parts Information
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info > Page 8853
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Cover > Component Information > Technical Service
Bulletins > Interior - Seat Cover Wrinkle/Crease/Burn Info > Page 8854
Seat Cover: Technical Service Bulletins Leather Seat Covers - Cleaning Procedure
File In Section: 10 - Body Bulletin No.: 43-16-06 Date: October, 1994
Subject: Cleaning Procedure for Leather Seat Covers
Models: 1995 and Prior Passenger Cars and "C/K" and "S/T" Trucks
If leather seat covers are being returned only because they are dirty, a more aggressive cleaning
procedure is recommended by General Motors prior to replacing covers.
Procedure
Dirty or soiled leather seat covers should be cleaned with a mild soap and water solution, using
clean soft cloths. When this procedure proves inadequate, a commercially available leather
cleaner, "Tanner's Preserve Leather Cleaner"* should be used with a 3M "Type T"* scrubbing pad.
Important:
The type of scrubbing pad is very critical because the common 3M Scotch-Brite green pad is too
aggressive and will damage the leather finish.
The cleaner is available from "First Brands" by calling 1-800-726-1001, identifying yourself as a GM
dealership, requesting "Tanner's Preserve Leather Cleaner" product, number AS-330, quantity and
shipping address. This product is also available at stores.
The 3M "Type T" scrubbing pad is available from a 3M distributor. Call 1-800-742-9546 for the
nearest distributor and then request the Scotch-Brite Clean and Finish Sheet, "Type T", in 6 x 9
inch sheets, UPC code number 048011-01276.
* We believe these sources and their equipment to be reliable. There may be additional
manufacturers of such equipment. General Motors does not endorse, indicate any preference for or
assume any responsibility for the products or equipment from these firms or for any such items
which may be available from other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Heater Control Module > Component Information >
Locations > Driver Seat Heater Control Module
Seat Heater Control Module: Locations Driver Seat Heater Control Module
Attached to seat support, under LH Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Heater Control Module > Component Information >
Locations > Driver Seat Heater Control Module > Page 8859
Underside Of Driver Seat, Passenger Seat Similar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Heater Switch > Component Information > Locations >
Driver Seat Heater Switch
Seat Heater Switch: Locations Driver Seat Heater Switch
LH side of Driver's Seat Cushion
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Seats > Seat Heater Switch > Component Information > Locations >
Driver Seat Heater Switch > Page 8864
Seat Heater Switch: Locations Passenger Seat Heater Switch
LH side of Passenger Seat Cushion
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Door Lock Switch >
Component Information > Locations > Component Locations
Power Door Lock Switch: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Door Lock Switch >
Component Information > Locations > Component Locations > Page 8870
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Door Lock Switch >
Component Information > Locations > Component Locations > Page 8871
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Door Lock Switch >
Component Information > Locations > Page 8872
Power Door Lock Switch RH And LH Front
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Mirror Switch >
Component Information > Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Locations > Component Locations
Power Seat Switch: Component Locations
Driver Seat Switch Pod
Bottom Of driver Seat, outboard Side
Passenger Seat Switch Pod
Part of bottom Driver Seat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Locations > Component Locations > Page 8880
Power Seat Switch: Connector Locations
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Locations > Component Locations > Page 8881
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Diagrams > LH and RH Lumbar Switch Assembly
C312 & C313: LH And RH Lumbar Switch Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Power Seat Switch >
Component Information > Diagrams > LH and RH Lumbar Switch Assembly > Page 8884
Power Seat Switch LH And RH
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Seat Heater Switch >
Component Information > Locations > Driver Seat Heater Switch
Seat Heater Switch: Locations Driver Seat Heater Switch
LH side of Driver's Seat Cushion
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Seat Heater Switch >
Component Information > Locations > Driver Seat Heater Switch > Page 8889
Seat Heater Switch: Locations Passenger Seat Heater Switch
LH side of Passenger Seat Cushion
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Seat Memory Switch >
Component Information > Locations
Seat Memory Switch: Locations
LH Front door on armrest
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch >
Component Information > Locations > Component Locations
Trunk / Liftgate Switch: Component Locations
Trunk Lid With Pull-Down
Back View Of LH Instrument Panel
Rear Compartment Lid Enable Switch
Mounted on I/P Compartment
Rear Luggage Compartment With Pull-Down
Rear Compartment Lid Pull-Down Striker Switch
Attached to Rear Compartment Lid Pulldown Actuator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch >
Component Information > Locations > Component Locations > Page 8897
Rear Compartment Lid Pull-Down Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch >
Component Information > Locations > Component Locations > Page 8898
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Sensors and Switches - Body and Frame > Trunk / Liftgate Switch >
Component Information > Locations > Page 8899
Rear Glass Interlock/Push Button Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Tailgate > Component Information > Diagrams
Tailgate: Diagrams
C406: Body Harness To Tailgate Harness, Headlamp Automatic Control Module (C1), Remote
Control Door Lock Receiver
C405: Body Harness To Tailgate Harness
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Body and Frame > Weatherstrip > Component Information > Technical Service Bulletins >
Body - Maintaining Exterior Weatherstrip Appearance
Weatherstrip: Technical Service Bulletins Body - Maintaining Exterior Weatherstrip Appearance
INFORMATION
Bulletin No.: 99-08-64-016C
Date: July 29, 2009
Subject: Information on Maintaining Exterior Weatherstrip Appearance
Models:
2010 and Prior Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add model years and update the parts and procedure
information. Please discard Corporate Bulletin Number 99-08-64-016B (Section 08 - Body and
Accessories).
Exterior weatherstrips are exposed to a variety of environmental elements, including UV rays, acid
rain, insect and bird residue and atmospheric fallout. All of these may effect the appearance of the
weatherstrips; however, they do not effect the functionality of the weatherstrip.
Weatherstrips that are discolored should not be replaced under the normal GM New Vehicle
Warranty.
Weatherstrip Maintenance Instructions
Silicone grease on weatherstrips will make them last longer, seal better, and not stick or squeak.
Clean the weatherstrips with a mild soap and water solution. Apply silicone grease with a clean
cloth. During very cold, damp weather, frequent application may be required. Refer to the
information below for the recommended maintenance products. Weatherstrips that are not
maintained may crack and weather due to environmental elements.
Parts Information
Weatherstrip Conditioning Weatherstrip Lubricant (GM P/N 3634770 [in Canada, P/N 10953518])
or Dielectric Silicone Grease (GM P/N 12345579 [in Canada, P/N 992887]).
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Brake Switch (Cruise Control) > Component Information > Service and
Repair
Brake Switch (Cruise Control): Service and Repair
Fig. 3 Cruise Control Release Switch & Stop Lamp Switch Assemblies
1. Disconnect electrical connectors, then remove release switch and stop lamp switch assemblies
from retainers, Fig. 3. 2. Remove retainers from bracket. 3. Reverse procedure to install. Adjust as
outlined.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Module > Component Information > Locations
LH Rear Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Module > Component Information > Locations > Page 8914
Cruise Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Module > Component Information > Locations > Page 8915
Cruise Control Module: Description and Operation
DESCRIPTION
The module has an electronic controller and an electric stepper motor to vary the throttle with each
different cruise mode. The module is not serviceable and must be replaced as an assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Module > Component Information > Locations > Page 8916
Cruise Control Module: Service and Repair
Fig. 36 Cruise Control Module Removal
1. Disconnect battery ground cable. 2. Disconnect electrical connector from module, Fig. 36. 3.
Disconnect cruise control cable from module, then remove bolts and screws. 4. Remove module
and plugs. 5. Remove plugs from module if a new module is being installed. 6. Reverse procedure
to install noting the following:
a. Align holes in accelerator and cruise control adjuster bracket to holes in wheel house panel and
position module on wheel house panel. b. Torque module bolts and screws to 71 ft. lbs. c. Adjust
cable, if necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Servo Cable > Component Information > Adjustments
Cruise Control Servo Cable: Adjustments
1. Remove air cleaner and resonator. 2. Unlock cable conduit at support bracket. 3. With throttle
closed, lock cable conduit by pressing down on lock tab. 4. When cable is in unlocked position and
throttle is closed, cable adjustment spring removes appropriate amount of slack. 5. Lock button
must be fully extended to allow proper adjustment spring operation prior to locking. 6. Install air
cleaner and resonator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Servo Cable > Component Information > Adjustments >
Page 8920
Cruise Control Servo Cable: Service and Repair
Fig. 30 Cruise Control Cable Retainer Removal.
Fig. 31 Cruise Control Cable Removal
The cable is connected between the cruise control module and throttle body lever. 1. Remove air
cleaner and resonator. 2. Remove cable and conduit from engine bracket, Fig. 30. 3. Remove
cable end fitting from throttle body lever stud. 4. Remove cruise control retainer at module. 5.
Remove cable from module as follows:
a. Compress conduit tangs, Fig. 31, and pull out of module housing. b. Disconnect cable bead from
cruise motor band end fitting on module, Fig. 31. c. Note routing and remove cable.
6. Reverse procedure to install noting the following:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Servo Cable > Component Information > Adjustments >
Page 8921
a. Ribbon must not be twisted, slide cable conduit fitting over ribbon and snap into module housing.
Ensure both tangs are engaged. b. Adjust cable as outlined under Adjustments. See: Adjustments
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Switch > Component Information > Locations > Component
Locations
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Switch > Component Information > Locations > Component
Locations > Page 8926
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Switch > Component Information > Locations > Component
Locations > Page 8927
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Switch > Component Information > Locations > Page 8928
C215: Cruise Control Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Switch > Component Information > Locations > Page 8929
Cruise Control Switch: Description and Operation
Fig. 3 Cruise Control Release Switch & Stop Lamp Switch Assemblies
DESCRIPTION
The release switch and stop lamp switch cannot be adjusted until after the brake booster pushrod
is assembled to brake pedal assembly. Refer to Fig. 3 when performing this procedure.
OPERATION
1. Depress brake pedal and insert release switch and stop lamp switch assembly into retainers until
fully seated. 2. Slowly release brake pedal back to its original position. Release switch and stop
lamp switch assemblies will move within retainers to their
adjusted position.
3. The following brake pedal travel distances can be used to check for properly adjusted release
switch and stop lamp switch assemblies:
a. Release switch and stop lamp switch assemblies contacts must be open at 1/8-1/2 inch brake
pedal travel, measured at centerline of brake pedal
pad.
b. Nominal actuation of stop lamp switch contacts is about 3/16 inch after cruise switch control
contacts close.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Cruise Control Switch > Component Information > Locations > Page 8930
Cruise Control Switch: Service and Repair
The engagement switch is not serviceable. The complete turn signal, headlamp dimmer switch,
cruise control actuator and windshield wiper/washer must be replaced as an assembly. 1.
Disconnect battery ground cable. 2. Remove steering column access cover, then disconnect
electrical connector. Ensure windshield wiper switch is in Off position. 3. Remove lever assembly
by pulling straight out. 4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations
LH Rear Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations > Page 8935
Cruise Control Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations > Page 8936
Cruise Control Module: Description and Operation
DESCRIPTION
The module has an electronic controller and an electric stepper motor to vary the throttle with each
different cruise mode. The module is not serviceable and must be replaced as an assembly.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Relays and Modules - Cruise Control > Cruise Control Module >
Component Information > Locations > Page 8937
Cruise Control Module: Service and Repair
Fig. 36 Cruise Control Module Removal
1. Disconnect battery ground cable. 2. Disconnect electrical connector from module, Fig. 36. 3.
Disconnect cruise control cable from module, then remove bolts and screws. 4. Remove module
and plugs. 5. Remove plugs from module if a new module is being installed. 6. Reverse procedure
to install noting the following:
a. Align holes in accelerator and cruise control adjuster bracket to holes in wheel house panel and
position module on wheel house panel. b. Torque module bolts and screws to 71 ft. lbs. c. Adjust
cable, if necessary.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Brake Switch (Cruise Control) >
Component Information > Service and Repair
Brake Switch (Cruise Control): Service and Repair
Fig. 3 Cruise Control Release Switch & Stop Lamp Switch Assemblies
1. Disconnect electrical connectors, then remove release switch and stop lamp switch assemblies
from retainers, Fig. 3. 2. Remove retainers from bracket. 3. Reverse procedure to install. Adjust as
outlined.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Cruise Control Switch >
Component Information > Locations > Component Locations
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Cruise Control Switch >
Component Information > Locations > Component Locations > Page 8946
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Cruise Control Switch >
Component Information > Locations > Component Locations > Page 8947
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Cruise Control Switch >
Component Information > Locations > Page 8948
C215: Cruise Control Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Cruise Control Switch >
Component Information > Locations > Page 8949
Cruise Control Switch: Description and Operation
Fig. 3 Cruise Control Release Switch & Stop Lamp Switch Assemblies
DESCRIPTION
The release switch and stop lamp switch cannot be adjusted until after the brake booster pushrod
is assembled to brake pedal assembly. Refer to Fig. 3 when performing this procedure.
OPERATION
1. Depress brake pedal and insert release switch and stop lamp switch assembly into retainers until
fully seated. 2. Slowly release brake pedal back to its original position. Release switch and stop
lamp switch assemblies will move within retainers to their
adjusted position.
3. The following brake pedal travel distances can be used to check for properly adjusted release
switch and stop lamp switch assemblies:
a. Release switch and stop lamp switch assemblies contacts must be open at 1/8-1/2 inch brake
pedal travel, measured at centerline of brake pedal
pad.
b. Nominal actuation of stop lamp switch contacts is about 3/16 inch after cruise switch control
contacts close.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Cruise Control Switch >
Component Information > Locations > Page 8950
Cruise Control Switch: Service and Repair
The engagement switch is not serviceable. The complete turn signal, headlamp dimmer switch,
cruise control actuator and windshield wiper/washer must be replaced as an assembly. 1.
Disconnect battery ground cable. 2. Remove steering column access cover, then disconnect
electrical connector. Ensure windshield wiper switch is in Off position. 3. Remove lever assembly
by pulling straight out. 4. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Sensors and Switches - Cruise Control > Vehicle Speed
Sensor/Transducer - Cruise Control > Component Information > Description and Operation
Vehicle Speed Sensor/Transducer - Cruise Control: Description and Operation
DESCRIPTION
The Vehicle Speed Sensor (VSS) buffer receives a signal from the VSS (permanent magnet
generator) indicating vehicle speed. The buffer processes the signal which is then sent to the
Engine Control Module (ECM), cruise control module and speedometer.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Cruise Control > Vehicle Speed Sensor/Transducer - Cruise Control > Component
Information > Description and Operation
Vehicle Speed Sensor/Transducer - Cruise Control: Description and Operation
DESCRIPTION
The Vehicle Speed Sensor (VSS) buffer receives a signal from the VSS (permanent magnet
generator) indicating vehicle speed. The buffer processes the signal which is then sent to the
Engine Control Module (ECM), cruise control module and speedometer.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > ABS Light > Component Information >
Description and Operation
ABS Light: Description and Operation
This lamp will be illuminated when the ignition switch is placed in the ON position. The lamp may
be illuminated for as long as 30 seconds as a bulb and system check. If lamp remains illuminated
or comes on while operating the vehicle, a problem in the anti-lock brake system is indicated.
When lamp is illuminated, place ignition switch in OFF position, then restart engine. If lamp still
remains illuminated, the anti-lock brake system should be serviced. The brake system will remain
functional, but without the anti-lock function. After servicing the anti-lock brake system the lamp will
automatically reset. On some models it may be necessary to operate vehicle at a speed over 18
mph to reset lamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Air Conditioning Indicator Lamp >
Component Information > Service and Repair
Air Conditioning Indicator Lamp: Service and Repair
This lamp will be illuminated when the A/C system detects a low refrigerant charge. The lamp will
be illuminated for approximately 2 seconds after ignition switch has been placed in the On position
as a bulb check. If while operating vehicle, the lamp illuminates for approximately 60 seconds and
then goes off, the refrigerant level is low enough to cause reduced cooling capacity. At this point
the blower motor will increase speed to try to offset the loss in cooling capacity. The lamp will be
automatically reset after system has been checked and refrigerant charge has been brought to
proper level.
If lamp is illuminated for approximately 60 seconds after engine start up, the refrigerant charge may
be low enough to cause A/C compressor damage. When this condition is encountered, the A/C
compressor clutch is de-energized and the A/C system is switched from Auto to Econ. The system
will remain in Econ until necessary repairs are made and system is recharged. After completing
necessary repairs and recharging the system, A/C system operation will return to normal and the
lamp will be automatically reset.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Ammeter Gauge > Component
Information > Description and Operation
Ammeter Gauge: Description and Operation
DESCRIPTION
The CS generator uses a new type of regulator which has a built in fault detection. The CS
generator does not have a diode trio or test hole. This generator uses only two connections, battery
positive and an "L" terminal to the charge indicator bulb. Use of " P", "F" and "S" terminals is
optional. The "P" terminal is connected to the stator and may be connected to a tachometer or
other device. The "F" terminal is connected internally to field positive and is used in service
diagnostics. The "S" terminal may be connected externally to a voltage source, such as battery
voltage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Ammeter Gauge > Component
Information > Description and Operation > Page 8967
Ammeter Gauge: Testing and Inspection
If charge indicator light works abnormally, perform the following test procedure:
1. Visually check belt and wiring. 2. With engine control switch ON and engine stopped, charge
indicator lamp should be on. If lamp is not on, detach wiring harness at generator and
ground "L" terminal. If lamp lights, generator is faulty. If lamp does not light, locate open circuit
between grounding lead and ignition switch and check for a faulty bulb.
3. With engine control switch ON and engine running at a moderate speed, charge indicator lamp
should be off. If lamp is not off, detach wiring
harness at generator. If lamp goes off, generator is faulty. If lamp stays on, check for grounded "L"
terminal in wire harness.
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Convenience Center
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LH Side Of Instrument Panel
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Audible Warning Device: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Audible Warning Device: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Audible Warning Device: Electrical Diagrams
Audible Warning (Part 1 Of 2)
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Audible Warning (Part 2 Of 2)
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Audible Warning Device: Description and Operation Courtesy Lamps
When CKT 156 is pulled low because a door has been opened, the Alarm will ground CKT 1393.
When CKT 1393 is pulled low, the relay contacts in the Dome Courtesy Relay will close, allowing
CKT 149 to go low via CKT 450. CKT 149 is the ground side of the Courtesy Light System. CKT
149 can also be grounded at the Headlamp/Panel Dimmer Switch.
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Audible Warning Device: Description and Operation Fasten Seat Belt Warning
The Alarm applies voltage to the Seat Belt Switch at all times. The Alarm senses a voltage drop at
the Seat Belt Latch Signal through the closed contacts of the Seat Belt Switch when the driver's
seat belt is unlatched. When the driver's seat belt is latched, the Seat Belt Switch is opened and
the Alarm senses voltage at the Seat Belt Latch Signal. When the Ignition Switch is turned to
"RUN," voltage is applied to the Alarm Ignition Signal. When voltage is present at the Ignition
Signal and no voltage is present at the Seat Belt Latch Signal, the Alarm will, sound the Fasten
Seat Belt Warning for about 5 to 8 seconds. If voltage is present at the Ignition Signal and the Seat
Belt Latch Signal, the Alarm will disable the Fasten Seat Belt Warning Chime. When the Ignition
Switch is turned to "RUN," the Alarm senses voltage at the Ignition Signal. When voltage is applied
to the Ignition Signal, the Alarm applies voltage to the "FASTEN SEAT BELT" Indicator for 5 to 8
seconds independent of the Seat Belt Switch and Fasten Seat Belt Warning chime.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Description and Operation > Courtesy Lamps > Page 9011
Audible Warning Device: Description and Operation General Information
The Seat Belt/Ignition Key/Lamps/Turn Signal Alarm generates three audible warnings which are:
Lights "ON" Warning and Turn Signal "ON" Reminder, Ignition Key Warning and Fasten Seat Belt
Warning. Each warning is a series of pulsed tones or chimes. The Lights "ON" Warning and Turn
Signal "ON" Reminder are pulsed approximately every one half second, sounding the quickest. The
Ignition Key Warning is pulsed once every second. The Fasten Seat Belt Warning is pulsed
approximately once every 1 1/2 seconds, sounding the slowest.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Description and Operation > Courtesy Lamps > Page 9012
Audible Warning Device: Description and Operation Illuminated Entry
When a door is opened and closed, the Courtesy Lamps will stay "ON" for 30-40 seconds unless
the Ignition Switch is turned to the "RUN" position. Voltage on CKT 639 will cause the Courtesy
Lamps to shut "OFF" immediately. If the vehicle (Buick only) is equipped with Keyless Entry (AUO),
the RCDLR will ground CKT 1393 for 30-40 seconds, unless the Ignition Switch is in the "RUN"
position. Refer to Keyless Entry Schematic Details. See: Accessories and Optional
Equipment/Antitheft and Alarm Systems/Remote Keyless Entry/Diagrams/Electrical Diagrams
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Description and Operation > Courtesy Lamps > Page 9013
Audible Warning Device: Description and Operation
Courtesy Lamps
When CKT 156 is pulled low because a door has been opened, the Alarm will ground CKT 1393.
When CKT 1393 is pulled low, the relay contacts in the Dome Courtesy Relay will close, allowing
CKT 149 to go low via CKT 450. CKT 149 is the ground side of the Courtesy Light System. CKT
149 can also be grounded at the Headlamp/Panel Dimmer Switch.
Fasten Seat Belt Warning
The Alarm applies voltage to the Seat Belt Switch at all times. The Alarm senses a voltage drop at
the Seat Belt Latch Signal through the closed contacts of the Seat Belt Switch when the driver's
seat belt is unlatched. When the driver's seat belt is latched, the Seat Belt Switch is opened and
the Alarm senses voltage at the Seat Belt Latch Signal. When the Ignition Switch is turned to
"RUN," voltage is applied to the Alarm Ignition Signal. When voltage is present at the Ignition
Signal and no voltage is present at the Seat Belt Latch Signal, the Alarm will, sound the Fasten
Seat Belt Warning for about 5 to 8 seconds. If voltage is present at the Ignition Signal and the Seat
Belt Latch Signal, the Alarm will disable the Fasten Seat Belt Warning Chime. When the Ignition
Switch is turned to "RUN," the Alarm senses voltage at the Ignition Signal. When voltage is applied
to the Ignition Signal, the Alarm applies voltage to the "FASTEN SEAT BELT" Indicator for 5 to 8
seconds independent of the Seat Belt Switch and Fasten Seat Belt Warning chime.
General Information
The Seat Belt/Ignition Key/Lamps/Turn Signal Alarm generates three audible warnings which are:
Lights "ON" Warning and Turn Signal "ON" Reminder, Ignition Key Warning and Fasten Seat Belt
Warning. Each warning is a series of pulsed tones or chimes. The Lights "ON" Warning and Turn
Signal "ON" Reminder are pulsed approximately every one half second, sounding the quickest. The
Ignition Key Warning is pulsed once every second. The Fasten Seat Belt Warning is pulsed
approximately once every 1 1/2 seconds, sounding the slowest.
Illuminated Entry
When a door is opened and closed, the Courtesy Lamps will stay "ON" for 30-40 seconds unless
the Ignition Switch is turned to the "RUN" position. Voltage on CKT 639 will cause the Courtesy
Lamps to shut "OFF" immediately. If the vehicle (Buick only) is equipped with Keyless Entry (AUO),
the RCDLR will ground CKT 1393 for 30-40 seconds, unless the Ignition Switch is in the "RUN"
position. Refer to Keyless Entry Schematic Details. See: Accessories and Optional
Equipment/Antitheft and Alarm Systems/Remote Keyless Entry/Diagrams/Electrical Diagrams
Key-In-Ignition Warning
The Alarm applies voltage at all times to the Ignition Key Alarm Switch. When the Ignition Key is
placed into the Ignition Lock Cylinder, the Ignition Key Alarm Switch is closed. When the LH front
door is open, the LH Front Door Jamb Switch closes the circuit to ground. The Alarm senses a
voltage drop at the Ignition Key Signal and will sound the Ignition Key Warning.
Lamps on Warning
When the Headlamp Switch is in "PARK" or "HEAD", voltage is applied to the Lights "ON" Signal of
the Alarm. When the Ignition Switch is turned out of the "RUN" position, voltage is removed from
the Ignition Signal of the Alarm. When voltage is present at the Lights "ON" Signal and no voltage
applied to the Ignition Signal, the Alarm will sound the Lights "ON" Warning. For non-T82 vehicles,
the Lights "ON" Warning can be turned OFF by turning the Instrument Panel Dimmer Switch to the
"OFF" position.
Turn Signal on Reminder
When a turn signal is operated, the Alarm begins to monitor the distance the vehicle has travelled.
If a turn signal is still flashing after the vehicle has travelled 0.8 km (0.5 mile), the Alarm turns the
Lights "ON" Warning on. The Lights "ON" Warning continues to sound until the turn signal is turned
"OFF."
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures
Audible Warning Device: Diagnostic Trouble Code Tests and Associated Procedures
System Check
System Diagnosis
Perform the System Check in the order shown. When a fault is found, refer to the Symptom Table
for the appropriate diagnostic procedure(s). If a normal result is found at each and every step of the
System Check, the fault may be intermittent. See: System Check See: Symptom Related
Diagnostic Procedures/Symptom Table
To help isolate an intermittent fault first examine the mating terminals at each component and
connector for a poor connection. Also check that each terminal of mating connectors is properly
seated in the connector body. If the connections appear to be reliable, try the System Check again
while moving the wiring harness from side to side at each component and in-line connector, to try
and induce the intermittent fault. Once a fault has been corrected, perform the System Check to
verify the diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9016
Audible Warning Device: Symptom Related Diagnostic Procedures
Chart #1 All Warning Alarms Inoperative
Chart #2 Ignition Key Warning Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9017
Chart #3 FASTEN SEAT BELT Warning Inoperative
Chart #4 FASTEN SEAT BELT Indicator ON Continuously
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9018
Chart #5 FASTEN SEAT BELT Indicator Inoperative
Chart #6 Turn Signal ON Reminder Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9019
Chart #7 Courtesy Lights Are Inoperative With DOOR(S) OPEN (Non-SEO)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9020
Chart #8 Courtesy Lights Stay ON Continuously (Non-SEO)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9021
Symptom Table (Part 1 Of 2)
Symptom Table (Part 2 Of 2)
Troubleshooting Hints
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Check I/P Fuse Block Fuse #33. If open, check for a short to ground in CKT 40. 2. Check I/P
Fuse Block Fuse #13. If open, check for a short to ground in CKT 639. 3. Check I/P Fuse Block
Fuse #12. If open, check for a short to ground in CKT 239. 4. Check that ground G200 is clean and
tight. 5. If Speedometer or Cruise Control (if equipped) does not operate properly refer to "Vehicle
Speed Sensor." See: Powertrain
Management/Computers and Control Systems/Sensors and Switches - Computers and Control
Systems/Vehicle Speed Sensor/Testing and Inspection/Symptom Related Diagnostic Procedures/Symptom Diagnostic Charts
^ Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
^ Refer to System Diagnosis. See: Diagnostic Trouble Code Tests and Associated
Procedures/System Diagnosis
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Audible Warning Device > Component
Information > Testing and Inspection > Diagnostic Trouble Code Tests and Associated Procedures > Page 9022
Audible Warning Device: Component Tests and General Diagnostics
Courtesy Lamps
When CKT 156 is pulled low because a door has been opened, the Alarm will ground CKT 1393.
When CKT 1393 is pulled low, the relay contacts in the Dome Courtesy Relay will close, allowing
CKT 149 to go low via CKT 450. CKT 149 is the ground side of the Courtesy Light System. CKT
149 can also be grounded at the Headlamp/Panel Dimmer Switch.
Fasten Seat Belt Warning
The Alarm applies voltage to the Seat Belt Switch at all times. The Alarm senses a voltage drop at
the Seat Belt Latch Signal through the closed contacts of the Seat Belt Switch when the driver's
seat belt is unlatched. When the driver's seat belt is latched, the Seat Belt Switch is opened and
the Alarm senses voltage at the Seat Belt Latch Signal. When the Ignition Switch is turned to
"RUN," voltage is applied to the Alarm Ignition Signal. When voltage is present at the Ignition
Signal and no voltage is present at the Seat Belt Latch Signal, the Alarm will, sound the Fasten
Seat Belt Warning for about 5 to 8 seconds. If voltage is present at the Ignition Signal and the Seat
Belt Latch Signal, the Alarm will disable the Fasten Seat Belt Warning Chime. When the Ignition
Switch is turned to "RUN," the Alarm senses voltage at the Ignition Signal. When voltage is applied
to the Ignition Signal, the Alarm applies voltage to the "FASTEN SEAT BELT" Indicator for 5 to 8
seconds independent of the Seat Belt Switch and Fasten Seat Belt Warning chime.
General Informations
The Seat Belt/Ignition Key/Lamps/Turn Signal Alarm generates three audible warnings which are:
Lights "ON" Warning and Turn Signal "ON" Reminder, Ignition Key Warning and Fasten Seat Belt
Warning. Each warning is a series of pulsed tones or chimes. The Lights "ON" Warning and Turn
Signal "ON" Reminder are pulsed approximately every one half second, sounding the quickest. The
Ignition Key Warning is pulsed once every second. The Fasten Seat Belt Warning is pulsed
approximately once every 1 1/2 seconds, sounding the slowest.
Ignition Key Warning
The Alarm applies voltage at all times to the Ignition Key Alarm Switch. When the Ignition Key is
placed into the Ignition Lock Cylinder, the Ignition Key Alarm Switch is closed. When the LH front
door is open, the LH Front Door Jamb Switch closes the circuit to ground. The Alarm senses a
voltage drop at the Ignition Key Signal and will sound the Ignition Key Warning.
Illuminated Entry
When a door is opened and closed, the Courtesy Lamps will stay "ON" for 30-40 seconds unless
the Ignition Switch is turned to the "RUN" position. Voltage on CKT 639 will cause the Courtesy
Lamps to shut "OFF" immediately. If the vehicle (Buick only) is equipped with Keyless Entry (AUO),
the RCDLR will ground CKT 1393 for 30-40 seconds, unless the Ignition Switch is in the "RUN"
position. Refer to Keyless Entry Schematic Details. See: Accessories and Optional
Equipment/Antitheft and Alarm Systems/Remote Keyless Entry/Diagrams/Electrical Diagrams
Lamps-ON Warning Alarm
When the Headlamp Switch is in "PARK" or "HEAD", voltage is applied to the Lights "ON" Signal of
the Alarm. When the Ignition Switch is turned out of the "RUN" position, voltage is removed from
the Ignition Signal of the Alarm. When voltage is present at the Lights "ON" Signal and no voltage
applied to the Ignition Signal, the Alarm will sound the Lights "ON" Warning. For non-T82 vehicles,
the Lights "ON" Warning can be turned OFF by turning the Instrument Panel Dimmer Switch to the
"OFF" position.
Turn Signal on Reminder
When a turn signal is operated, the Alarm begins to monitor the distance the vehicle has travelled.
If a turn signal is still flashing after the vehicle has travelled 0.8 km (0.5 mile), the Alarm turns the
Lights "ON" Warning on. The Lights "ON" Warning continues to sound until the turn signal is turned
"OFF."
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions
Brake Warning Indicator: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Information > Diagrams > Diagram Information and Instructions > Page 9027
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Information > Diagrams > Diagram Information and Instructions > Page 9028
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Information > Diagrams > Diagram Information and Instructions > Page 9029
Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Information > Diagrams > Diagram Information and Instructions > Page 9031
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Information > Diagrams > Diagram Information and Instructions > Page 9032
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Information > Diagrams > Diagram Information and Instructions > Page 9033
Brake Warning Indicator: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Information > Diagrams > Diagram Information and Instructions > Page 9034
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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Information > Diagrams > Diagram Information and Instructions > Page 9035
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Information > Diagrams > Diagram Information and Instructions > Page 9036
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9051
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9052
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9053
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9054
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9055
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9056
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9057
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Diagrams > Diagram Information and Instructions > Page 9058
Brake Warning System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Description and Operation > Brake Warning System
Brake Warning Indicator: Description and Operation Brake Warning System
DESCRIPTION
The "Brake" warning indicator will be illuminated when a low brake fluid level in the master cylinder
is sensed or when the Electronic Brake Control Module (EBCM) lights it in response to certain
diagnostic trouble codes.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Description and Operation > Brake Warning System > Page 9061
Brake Warning Indicator: Description and Operation Circuit Operation
Voltage is applied to the "BRAKE" Indicator from I/P Fuse #11 when the Ignition Switch is turned to
"RUN," "BULB TEST" or "START." The "BRAKE" Indicator is controlled by any one of three
switches: the Brake Pressure Switch, Ignition Switch or Park Brake Indicator Switch. When the
Ignition Switch is turned to "BULB TEST" or "START," CKT 209 is grounded through the Ignition
Switch to activate the "BRAKE" Indicator. When the Brake Pressure Switch is closed, CKT 209 is
grounded through the contacts of the Brake Pressure Switch to activate the "BRAKE" Indicator.
CKT 33 is grounded through the Park Brake Switch when the Park Brake is set, to activate the
"BRAKE" Indicator. With the Daytime Running Lamps (DRL) Control Module grounded through
CKT 33, the module provides ground to CKT 209, lighting the "BRAKE" Indicator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Description and Operation > Brake Warning System > Page 9062
Brake Warning Indicator: Description and Operation Brake Pressure Warning Lamp
DESCRIPTION
The warning lamp should illuminate when the ignition switch is in the start position, and turn off
when the switch returns to run. If the brake lamp remains on after the ignition returns to run, check
fluid level in master cylinder reservoir and inspect parking brake. If the warning lamp does not turn
on during cranking, check for defective bulb or blown fuse.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview
Brake Warning Indicator: Initial Inspection and Diagnostic Overview
Circuit Operation
Voltage is applied to the "BRAKE" Indicator from I/P Fuse #11 when the Ignition Switch is turned to
"RUN," "BULB TEST" or "START." The "BRAKE" Indicator is controlled by any one of three
switches: the Brake Pressure Switch, Ignition Switch or Park Brake Indicator Switch. When the
Ignition Switch is turned to "BULB TEST" or "START," CKT 209 is grounded through the Ignition
Switch to activate the "BRAKE" Indicator. When the Brake Pressure Switch is closed, CKT 209 is
grounded through the contacts of the Brake Pressure Switch to activate the "BRAKE" Indicator.
CKT 33 is grounded through the Park Brake Switch when the Park Brake is set, to activate the
"BRAKE" Indicator. With the Daytime Running Lamps (DRL) Control Module grounded through
CKT 33, the module provides ground to CKT 209, lighting the "BRAKE" Indicator.
System Diagnosis
^ Perform the System Check and refer to the Symptom Table for the appropriate diagnostic
procedure(s). See: System Check See: Symptom Related Diagnostic Procedures/Symptom Table
System Check
Troubleshooting Hints
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Check I/P Fuse Block Fuse #11. If Fuse #11 is open check for a short to ground in CKT 39. 2.
Check brake fluid level. If low, refer to Antilock Brake System. See: Brakes and Traction
Control/Antilock Brakes / Traction Control Systems ^
Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures."). See: Diagrams/Diagnostic Aids
^ Refer to System Diagnosis. See: System Diagnosis
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9065
Brake Warning Indicator: Symptom Related Diagnostic Procedures
Symptom Table
Chart #1 Ignition Switch Does Not Activate The BRAKE Indicator
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9066
Chart #2 Park Brake Does Not Activate The BRAKE Indicator (Base Or Twilight Sentinel)
Chart #3 Park Brake Does Not Activate The BRAKE IND (With DRL)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9067
Chart #4 BRAKE IND Stay ON W/IGN SW In RUN & Park Brake Released (Base/Twilight Sentinel)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9068
Chart #4 BRAKE IND Stays ON W/IGN SW In RUN & Park Brake Released (W/DRL)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Brake Warning Indicator > Component
Information > Testing and Inspection > Page 9069
Brake Warning Indicator: Service and Repair
This lamp will be illuminated when the ignition switch is placed in the ON position. The lamp may
be illuminated for as long as 30 seconds as a bulb and system check. If lamp remains illuminated
or comes on while operating the vehicle, a problem in the anti-lock brake system is indicated.
When lamp is illuminated, place ignition switch in OFF position, then restart engine. If lamp still
remains illuminated, the anti-lock brake system should be serviced. The brake system will remain
functional, but without the anti-lock function. After servicing the anti-lock brake system the lamp will
automatically reset. On some models it may be necessary to operate vehicle at a speed over 18
mph to reset lamp.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Check Gauges Lamp > Component
Information > Description and Operation
Check Gauges Lamp: Description and Operation
The "Check Gage" warning lamp will illuminate to warn the driver to check the oil pressure gauge,
engine coolant temperature gauge and the voltmeter. When lit, the "Check Gage" lamp indicates
that one of these gauges is operating in an abnormal range.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Cigarette Lighter > Component
Information > Technical Service Bulletins > Customer Interest for Cigarette Lighter: > 99-08-45-005 > Nov > 99 > Accessory
Receptacle/Cigar Lighter - Inoperative
Cigarette Lighter: Customer Interest Accessory Receptacle/Cigar Lighter - Inoperative
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-45-005
Date: November, 1999
TECHNICAL
Subject: Accessory Receptacle/Cigar Lighter is Inoperative (Check Aftermarket Device Plug for
Short to Ground)
Models: 1995-2000 Passenger Cars and Trucks
Condition
Some customers may comment that the cigar lighter or the accessory receptacle is inoperative; or
that the internal fuse (within the plug on an aftermarket device), blows intermittently.
Cause
Certain aftermarket devices have a newly designed power plug with an internal mini fuse. The mini
fuse may have an external terminal (which may be used to externally check the fuse). If the mini
fuse external test terminal is not recessed into the mini fuse body, it may come in contact with the
shell of the vehicle receptacle and cause the fuse (of either the vehicle or the aftermarket device),
to blow intermittently.
Correction
Test the aftermarket device plug for short to ground. The following step may be performed at the
customer's expense. As this is not a defect in material, design or workmanship of the vehicle, it
would be the owner's responsibility.
1. Place a piece of tape over the mini fuse terminal temporarily.
2. Explain to the customer that the fuse for the device must have no exposed terminals, and that
finding one would be his responsibility.
3. Refer the customer to the manufacturer of the aftermarket device for a new plug.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Cigarette Lighter > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Cigarette Lighter: > 99-08-45-005 > Nov > 99
> Accessory Receptacle/Cigar Lighter - Inoperative
Cigarette Lighter: All Technical Service Bulletins Accessory Receptacle/Cigar Lighter - Inoperative
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-45-005
Date: November, 1999
TECHNICAL
Subject: Accessory Receptacle/Cigar Lighter is Inoperative (Check Aftermarket Device Plug for
Short to Ground)
Models: 1995-2000 Passenger Cars and Trucks
Condition
Some customers may comment that the cigar lighter or the accessory receptacle is inoperative; or
that the internal fuse (within the plug on an aftermarket device), blows intermittently.
Cause
Certain aftermarket devices have a newly designed power plug with an internal mini fuse. The mini
fuse may have an external terminal (which may be used to externally check the fuse). If the mini
fuse external test terminal is not recessed into the mini fuse body, it may come in contact with the
shell of the vehicle receptacle and cause the fuse (of either the vehicle or the aftermarket device),
to blow intermittently.
Correction
Test the aftermarket device plug for short to ground. The following step may be performed at the
customer's expense. As this is not a defect in material, design or workmanship of the vehicle, it
would be the owner's responsibility.
1. Place a piece of tape over the mini fuse terminal temporarily.
2. Explain to the customer that the fuse for the device must have no exposed terminals, and that
finding one would be his responsibility.
3. Refer the customer to the manufacturer of the aftermarket device for a new plug.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Cigarette Lighter > Component
Information > Technical Service Bulletins > Page 9086
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Coolant Level Indicator Lamp >
Component Information > Description and Operation
Coolant Level Indicator Lamp: Description and Operation
DESCRIPTION
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
OPERATION
Some vehicles use a buzzer or indicator lamp to convey a low coolant level condition. The buzzer
or lamp is activated by a sensor, located in the radiator, when the coolant level becomes one quart
low, or more.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Coolant Level Indicator Lamp >
Component Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant Level Low
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator Off W/Coolant Level
Low
Fig. 97 Chart 6: Low Coolant Level Indicator Inoperative W/Coolant Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Coolant Level Indicator Lamp >
Component Information > Testing and Inspection > Low Coolant Indicator Off W/Coolant Level Low > Page 9092
Coolant Level Indicator Lamp: Testing and Inspection Low Coolant Indicator On w/Coolant Level
OK
Fig. 96 Chart 5: Low Coolant Level Indicator On W/Coolant Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Coolant Level Indicator Lamp >
Component Information > Testing and Inspection > Page 9093
Coolant Level Indicator Lamp: Service and Repair
This lamp will be illuminated when engine coolant level in the radiator drops below a predetermined
level. To turn lamp off, check cooling system, then add coolant to bring system to proper level.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dash Board / Instrument Panel <-->
[Dashboard / Instrument Panel] > Air Bag(s) Arming and Disarming > System Information > Service and Repair > Air Bag
Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dash Board / Instrument Panel <-->
[Dashboard / Instrument Panel] > Air Bag(s) Arming and Disarming > System Information > Service and Repair > Air Bag
Disarming and Arming > Page 9099
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dimmer Switch > Component
Information > Technical Service Bulletins > IP Dimmer Control - Proper Setting
Dimmer Switch: Technical Service Bulletins IP Dimmer Control - Proper Setting
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-42-009
Date: November, 1999
INFORMATION
Subject: Proper Setting of I/P Dimmer Control to View PRNDL Display with Automatic Headlamp
Control
Models: 2000 and Prior All Passenger Cars and Trucks With Automatic Headlamp Control and
Electronic PRNDL Display
Under certain conditions, if the instrument panel dimmer control is turned relatively low, the PRNDL
will not be visible until the automatic headlamp control turns the headlamps off and the daytime
running lamps (DRL) are turned back on. Such a condition may be if the vehicle is first started in an
environment where the headlamp control turns on the headlamps and then the vehicle is driven out
into a brighter environment (for example, when a vehicle is backed out of a dark garage into the
bright sunlight).
This condition is normal and any repair attempt will not be successful. Demonstrate this condition
to the customer using the service lane and then turn the instrument panel dimmer control to a
higher setting. This will enable the driver to see the PRNDL display
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dimmer Switch > Component
Information > Locations > Component Locations
Dimmer Switch: Component Locations
Lower LH Side Of Steering Column
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dimmer Switch > Component
Information > Locations > Component Locations > Page 9106
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dimmer Switch > Component
Information > Locations > Page 9107
Dimmer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Dimmer Switch > Component
Information > Locations > Page 9108
Dimmer Switch: Service and Repair
Fig. 13 Column Mounted Dimmer Switch Installation
1. Disconnect battery ground cable. 2. Remove instrument panel lower trim and on models with
A/C, remove A/C duct extension at column. 3. Disconnect shift indicator from column and remove
toe-plate cover screws. 4. Remove two nuts from instrument panel support bracket studs and lower
steering column, resting steering wheel on front seat. 5. Remove dimmer switch retaining screws,
then the switch. Tape actuator rod to column and separate switch from rod. 6. Reverse procedure
to install. To adjust switch, depress dimmer switch slightly and install a 3/32 inch twist drill to lock
switch to the body, Fig. 13.
Force switch upward to remove lash between switch and pivot, then remove tape from actuator
rod. Remove twist drill and check for proper operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door/Trunk Ajar Indicator/Lamp >
Component Information > Locations
Door/Trunk Ajar Indicator/Lamp: Locations
LH Side of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door/Trunk Ajar Indicator/Lamp >
Component Information > Testing and Inspection > Gate Ajar Indicator Inop
Door/Trunk Ajar Indicator/Lamp: Testing and Inspection Gate Ajar Indicator Inop
Fig. 100 Chart 9: Gate Ajar Indicator Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door/Trunk Ajar Indicator/Lamp >
Component Information > Testing and Inspection > Gate Ajar Indicator Inop > Page 9114
Door/Trunk Ajar Indicator/Lamp: Testing and Inspection Gate Ajar Indicator on at All Times
Fig. 101 Chart 10: Gate Ajar Indicator On At All Times
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door Switch > Component Information
> Locations > Door Jamb Switch, LH Front
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door Switch > Component Information
> Locations > Door Jamb Switch, LH Front > Page 9119
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door Switch > Component Information
> Locations > Door Jamb Switch, LH Front > Page 9120
Door Switch: Locations Door Jamb Switch, RH Front
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door Switch > Component Information
> Locations > Door Jamb Switch, LH Front > Page 9121
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Door Switch > Component Information
> Locations > Door Jamb Switch, LH Front > Page 9122
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge > Component Information
> Description and Operation > Fuel Gauge System
Fuel Gauge: Description and Operation Fuel Gauge System
DESCRIPTION
The fuel gauge system consists of a sending unit, instrument voltage regulator and an electric fuel
gauge. The sending unit is a variable resistor that is controlled by a float. Corresponding to actual
fuel level, the float will rise or fall. When the ignition is turned to the On position, voltage is applied
to the gauge through the voltage regulator, completing the gauge ground circuit through the
sending unit.
OPERATION
When the tank is full and the float is raised, maximum resistance (approximately 90 ohms) is
produced by the sending unit, current flow through the gauge is decreased, and the gauge pointer
moves slightly. As the tank empties and the float drops resistance in the sending unit decreases,
current flow through the gauge increases and the gauge pointer moves toward empty.
Most analog fuel gauges are of the free floating type, which means that the gauge pointer does not
remain against the full stop when the ignition is off. Rather, the pointer floats to a mid-position when
no voltage is applied to the gauge.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge > Component Information
> Description and Operation > Fuel Gauge System > Page 9127
Fuel Gauge: Description and Operation Fuel Usage
DESCRIPTION
This system consists of green and amber indicator lights located on the fuel gauge or telltale lamp
cluster, a switch mounted on the instrument panel behind the gauges and an interconnecting
vacuum hose and tee.
OPERATION
The system operates on engine vacuum through a dual contact vacuum sensing switch. When the
accelerator is operated slowly and smoothly, engine vacuum remains high and the switch passes
current to the green indicator light which indicates economical fuel consumption. When the
accelerator pedal is depressed rapidly, vacuum decreases and the switch passes current to the
amber indicator light, which indicates high fuel consumption. The amber indicator light will glow
when the ignition switch is in the On position with the engine stopped.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge > Component Information
> Testing and Inspection > Symptom Related Diagnostic Procedures
Fuel Gauge: Symptom Related Diagnostic Procedures
Fuel Gauge Inaccurate
Tester BT-6508 or equivalent must be used to diagnose dash gauge malfunction.
1. Ensure battery is fully charged, disconnect electrical connector to tank unit and connect tester to
between harness connector and suitable ground
following manufacturer's instructions.
2. Set tester on empty then turn on ignition. Gauge should read empty or below. 3. Set tester on
full. Gauge should read full or above. 4. If gauge does not respond to tester input, replace dash
gauge. If gauge responds correctly, check for poor connections at tank unit, poor tank unit
ground or defective tank unit.
Fuel Gauge Is Inaccurate or Inoperative
Fig. 103 Chart 1: Fuel Gauge Inoperative Or Inaccurate (Part 1 Of 2)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge > Component Information
> Testing and Inspection > Symptom Related Diagnostic Procedures > Page 9130
Fig. 103 Chart 1: Fuel Gauge Inoperative Or Inaccurate (Part 2 Of 2)
Gauge Reads Empty When Tank Is Full
This condition is generally caused by a short in the fuel tank unit circuit.
1. Disconnect electrical connector to sending unit, then turn ignition switch to ON position. 2. If
gauge reads past full, test gauge with tester tool No. BT-6508, or equivalent. If gauge reads empty,
disconnect main body harness connector,
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge > Component Information
> Testing and Inspection > Symptom Related Diagnostic Procedures > Page 9131
near the fuse block.
3. If gauge still shows empty, check for short in printed circuit or defective gauge. If gauge reads
beyond full, reconnect front body harness connector
and disconnect rear body harness connector (in left wheel house).
4. If gauge shows empty, locate and repair grounded wire in harness between front and rear body
harness connectors. If gauge reads beyond full,
check for short between rear body harness connector, damaged float or defective sending unit.
Gauge Reads Full or Beyond at All Times
This condition is generally caused by an open in the tank unit circuit.
1. Check tank unit ground for proper contact with body or chassis and repair as needed. 2. If tank
unit ground is satisfactory, disconnect electrical connector to tank unit and connect harness side of
connector to suitable ground with
jumper wire, then turn on ignition.
3. If gauge reads empty, remove fuel tank and inspect wiring to sending unit. If wiring and
connections are satisfactory, replace tank unit. 4. If gauge still shows full, disconnect front body
harness connector and ground fuel gauge wire terminal in instrument panel side of connector. 5. If
gauge still reads full, check for loose connection in cluster, open (crack) in printed circuit or
defective gauge. If gauge reads empty, locate and
repair open or poor connection between front body connector and tank unit connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge > Component Information
> Testing and Inspection > Symptom Related Diagnostic Procedures > Page 9132
Fuel Gauge: Component Tests and General Diagnostics
1. With ignition switch in the on position, ground each terminal at the economy switch. Both green
and amber indicator lights should glow. If not
check for burned out bulbs.
2. With ignition switch in On position, amber indicator light should glow. If not, check for loose or
disconnected wires at fuel economy switch or for
poor ground. If amber indicator light still does not glow replace switch.
3. Start engine and allow to idle, the green indicator light should glow. If not, check for leaking,
plugged or kinked vacuum hose between vacuum
source and fuel economy switch. Check for loose or disconnected wires at economy switch or poor
ground. If green indicator lamp still does not glow, replace switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge Sender > Component
Information > Locations
Fuel Gauge Sender: Locations
Mounted on Fuel Tank, Part of Fuel Tank Unit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Fuel Gauge Sender > Component
Information > Locations > Page 9136
Fuel Pump/Sender Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Locations > Heads Up Display (HUD) Projector
Heads Up Display Unit: Locations Heads Up Display (HUD) Projector
Customer Installed
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Locations > Heads Up Display (HUD) Projector > Page 9141
Heads Up Display Unit: Locations Night Vision Control Unit
Customer Installed
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Locations > Heads Up Display (HUD) Projector > Page 9142
Heads Up Display Unit: Locations Night Vision Roof Unit
Exterior of Roof
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions
Heads Up Display Unit: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9145
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9146
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9147
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9148
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9149
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9150
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Heads Up Display Unit > Component
Information > Diagrams > Diagram Information and Instructions > Page 9151
Heads Up Display Unit: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 9152
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 9153
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information > Diagrams > Diagram Information and Instructions > Page 9154
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Information > Diagrams > Diagram Information and Instructions > Page 9155
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Information > Diagrams > Diagram Information and Instructions > Page 9170
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Heads Up Display Unit: Electrical Diagrams
Heads Up Display (HUD): (HUD)
Special Equipment Option
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Heads Up Display (HUD): Night Vision (SEO) (UV1)
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Heads Up Display (HUD): Night Vision (SEO) (UV3)
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Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Instrument Cluster / Carrier <-->
[Instrument Cluster / Carrier] > Air Bag(s) Arming and Disarming > System Information > Service and Repair > Air Bag
Disarming and Arming
Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming
Disabling the SIR System
The diagnostic energy reserve module or sensing and diagnostic module (DERM/SDM) can
maintain enough voltage to cause air bag deployment for up to two minutes after the ignition switch
is turned off and the battery is disconnected. Servicing the SIR system during this period may result
in accidental deployment and personal injury.
1. Ensure front wheels are pointed straight ahead. 2. Turn ignition switch to LOCK position and
remove SIR or AIR BAG fuse. 3. Remove Connector Position Assurance (CPA), then disconnect
both yellow 2-way SIR electrical connectors at base of steering column. 4. Wait at least 2 minutes
before proceeding with diagnosis or service.
Enabling the SIR System
1. Connect both 2-way yellow connectors at base of steering column. 2. Install Connector Position
Assurance (CPA). 3. Install SIR or AIR BAG fuse into fuse block. 4. Turn ignition to the RUN
position and ensure that the "Inflatable Restraint lamp flashes seven to nine times and then turns
off. If lamp does not
operate as specified, refer to Testing And Inspection.
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[Instrument Cluster / Carrier] > Air Bag(s) Arming and Disarming > System Information > Service and Repair > Air Bag
Disarming and Arming > Page 9184
Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions
CAUTION; When performing service on or around SIR components or SIR wiring, follow the
procedures to temporarily disable the SIR system. Failure to follow procedures could result in
possible air bag deployment, personal injury, or otherwise unneeded SIR system repair.
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Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Instrument Cluster / Carrier <-->
[Instrument Cluster / Carrier] > Instrument Panel Bulb > Component Information > Locations
Front Of Instrument Panel
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Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Low Fuel Lamp/Indicator > Component
Information > Description and Operation
Low Fuel Lamp/Indicator: Description and Operation
DESCRIPTION
The switch type consists of an indicator light and a low fuel warning switch located on the
instrument panel.
OPERATION
The warning switch contacts are closed by the difference in voltage potential between the fuel
gauge terminals. This voltage differential will activate the warning switch when the fuel tank is less
than 1/4 full and, in turn, cause the indicator to light.
This system incorporates an indicator light. With ignition switch turned to On, the indicator should
light. If not, check bulb and all electrical connections. Replace warning switch if bulb and
connections prove satisfactory.
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Component Information > Diagrams > Diagram Information and Instructions
Malfunction Indicator Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Component Information > Diagrams > Diagram Information and Instructions > Page 9201
Malfunction Indicator Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions > Page 9220
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions > Page 9221
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions > Page 9222
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions > Page 9223
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions > Page 9224
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Malfunction Indicator Lamp >
Component Information > Diagrams > Diagram Information and Instructions > Page 9225
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Odometer > Component Information >
Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations
Odometer: Technical Service Bulletins Odometer/Speedometer - ACDelco Service Center
Locations
File In Section: 8 - Chassis/Body Electrical
Bulletin No.: 66-83-04A
Date: September, 1996
INFORMATION
Subject: AC Delco Service Center Locations for Odometer/Speedometer Service
Models: 1997 and Prior Passenger Cars and Trucks (excluding Cadillac)
This bulletin is being revised to provide the necessary contact information only. Please discard
Corporate Bulletin Number 66-83-04 (Section 8 - Chassis/Body Electrical)
General Motors provides service for sophisticated electronic products through the authorized AC
Delco Service Center Program. This program is designed to provide GM vehicle owners with the
highest quality and most technically up-to-date product available. Repair products from
unauthorized service outlets are not acceptable as warranty replacements.
Currently, there are 25 authorized AC Delco Service Centers who exchange and remanufacture
odometer/speedometers (list included). Only these Centers should be contacted for service.
Important:
W series and 1997 T series Medium Duty truck odometer/speedometers must be ordered directly
from GMSPO.
The following steps should be taken when utilizing the AC Delco Service Centers: Dealers should
contact their local AC Delco Service Center (list included). Any listed facility may be used.
The following information must be provided:
Part number VIN, Mileage, Vehicle Year, Make and Model Dealer Name and Address Delivery
Date of Vehicle Name of the person requesting exchange or service Phone number Repair Order
Number P.O. number (if non - warranty)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Odometer > Component Information >
Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations > Page 9230
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Odometer > Component Information >
Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations > Page 9231
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Odometer > Component Information >
Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations > Page 9232
AC Delco Service Centers
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Change Reminder Lamp >
Component Information > Service and Repair > Change Oil or Change Oil Now Message
Oil Change Reminder Lamp: Service and Repair Change Oil or Change Oil Now Message
1. Turn ignition switch to On position, without starting engine. 2. Press accelerator pedal to wide
open throttle (WOT) position and release three times within five seconds. 3. If Change Oil warning
indicator goes out, system has been reset. 4. If Change Oil warning indicator does not reset, turn
ignition switch Off and repeat procedure.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Change Reminder Lamp >
Component Information > Service and Repair > Change Oil or Change Oil Now Message > Page 9237
Oil Change Reminder Lamp: Service and Repair Engine Oil Life Monitor
ENGINE OIL LIFE MONITOR
The "CHANGE OIL" monitor light on the instrument cluster is a reminder to change oil. When
changing oil, reset the oil life monitor whether the "CHANGE OIL" light came on or not.
NOTE: Disconnecting the negative battery cable will not reset the oil life monitor.
Reset monitor as follows:
1. Turn ignition switch to "ON" position, but don't start engine. 2. Fully depress accelerator pedal to
Wide Open Throttle (WOT) position and release it three times within five seconds.
^ The light is controlled by the Powertrain Control Module (PCM). The PCM is monitoring the TPS
signal for 3 consecutive signals above
96%. The PCM will acknowledge, if the reset was successful, by flashing the "Change Oil" light
twice, then turning off the light.
3. If "CHANGE OIL" warning/indicator lamp flashes then goes out, the system has been reset. 4. If
"CHANGE OIL" warning/indicator lamp doesn't reset, turn ignition switch "OFF" and repeat
procedure.
^ If "CHANGE OIL" light is inoperative or remains "ON," refer to Powertrain Management /
Computerized Engine Controls / Testing
Procedures section. (DTC 95)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Level Warning Indicator >
Component Information > Description and Operation
Oil Level Warning Indicator: Description and Operation
DESCRIPTION
This lamp illuminates to warn the driver that the engine oil level is low. When the ignition switch is
first moved to Run, the oil level indicator lights for about 1 1/2 seconds as a bulb check. The oil
level detection circuit has two internal timers. The first timer records the amount of time the ignition
has been Off. The second timer records the amount of time the ignition has been On before the
ignition was shut Off. The instrument cluster uses this information to determine if the engine has
been sitting long enough for the oil to have returned to the oil pan.
OPERATION
The oil level monitoring circuits will check the oil level switch under the following conditions:
1. Ignition has been turned Off for more than 30 minutes. 2. Ignition has been Off for at least three
minutes after ignition has been On for at least 12 minutes.
If the oil level is low (oil level switch open), the "Check Oil" indicator will be turned On for the
remainder of the ignition cycle.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Level Warning Indicator >
Component Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator Inoperative W/Oil Level Low
Fig. 99 Chart 8: Low Oil Level Indicator Inoperative W/Oil Level Low
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Level Warning Indicator >
Component Information > Testing and Inspection > Low Oil Indicator Inoperative W/Oil Level Low > Page 9243
Oil Level Warning Indicator: Testing and Inspection Low Oil Indicator On w/Oil Level OK
Fig. 98 Chart 7: Low Oil Level Indicator On W/Oil Level OK
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Pressure Gauge > Component
Information > Description and Operation
Oil Pressure Gauge: Description and Operation
DESCRIPTION
This oil pressure indicating system incorporates an instrument voltage regulator, electrical oil
pressure gauge and a sending unit which are connected in series. The sending unit consists of a
diaphragm, contact and a variable resistor.
OPERATION
As oil pressure increases or decreases, the diaphragm actuated the contact on the variable
resistor, in turn controlling current flow through the gauge. When oil pressure is low, the resistance
of the variable resistor is high, restricting current flow to the gauge, in turn indicating low oil
pressure. As oil pressure increases, the resistance of the variable resistor is lowered, permitting an
increased current flow to the gauge, resulting in an increased gauge reading.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Pressure Gauge > Component
Information > Description and Operation > Page 9247
Oil Pressure Gauge: Service and Repair
Disconnect the oil pressure gauge lead from the sending unit, connect a 12 volt test lamp between
the gauge lead and the ground and turn ignition on. If test lamp flashes, the instrument voltage
regulator is functioning properly and the gauge circuit is not broken. If the test lamp remains lit, the
instrument voltage regulator is defective and must be replaced. If the test lamp does not light,
check the instrument voltage regulator for proper ground or an open circuit. Also, check for an open
in the instrument voltage regulator to oil pressure gauge wire or in the gauge itself. If test lamp
flashes and gauge is not accurate, the gauge may be out of calibration, requiring replacement.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Pressure Sender > Component
Information > Locations
Rear Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Oil Level Sensor <--> [Oil Temperature
Gauge] > Component Information > Testing and Inspection
Oil Level Sensor: Testing and Inspection
Check for a defective wire inside the insulation which could cause system malfunction but prove
"GOOD" in a continuity/voltage check with the system disconnected. These circuits may be
intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage
drop with the system operational.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Parking Brake Warning Switch >
Component Information > Locations > Park Brake Indicator Switch
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Parking Brake Warning Switch >
Component Information > Locations > Park Brake Indicator Switch > Page 9258
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Dimmer Switch > Component Information > Technical Service Bulletins > IP Dimmer Control - Proper Setting
Dimmer Switch: Technical Service Bulletins IP Dimmer Control - Proper Setting
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-42-009
Date: November, 1999
INFORMATION
Subject: Proper Setting of I/P Dimmer Control to View PRNDL Display with Automatic Headlamp
Control
Models: 2000 and Prior All Passenger Cars and Trucks With Automatic Headlamp Control and
Electronic PRNDL Display
Under certain conditions, if the instrument panel dimmer control is turned relatively low, the PRNDL
will not be visible until the automatic headlamp control turns the headlamps off and the daytime
running lamps (DRL) are turned back on. Such a condition may be if the vehicle is first started in an
environment where the headlamp control turns on the headlamps and then the vehicle is driven out
into a brighter environment (for example, when a vehicle is backed out of a dark garage into the
bright sunlight).
This condition is normal and any repair attempt will not be successful. Demonstrate this condition
to the customer using the service lane and then turn the instrument panel dimmer control to a
higher setting. This will enable the driver to see the PRNDL display
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Dimmer Switch > Component Information > Locations > Component Locations
Dimmer Switch: Component Locations
Lower LH Side Of Steering Column
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Dimmer Switch > Component Information > Locations > Component Locations > Page 9266
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Dimmer Switch > Component Information > Locations > Page 9267
Dimmer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Dimmer Switch > Component Information > Locations > Page 9268
Dimmer Switch: Service and Repair
Fig. 13 Column Mounted Dimmer Switch Installation
1. Disconnect battery ground cable. 2. Remove instrument panel lower trim and on models with
A/C, remove A/C duct extension at column. 3. Disconnect shift indicator from column and remove
toe-plate cover screws. 4. Remove two nuts from instrument panel support bracket studs and lower
steering column, resting steering wheel on front seat. 5. Remove dimmer switch retaining screws,
then the switch. Tape actuator rod to column and separate switch from rod. 6. Reverse procedure
to install. To adjust switch, depress dimmer switch slightly and install a 3/32 inch twist drill to lock
switch to the body, Fig. 13.
Force switch upward to remove lash between switch and pivot, then remove tape from actuator
rod. Remove twist drill and check for proper operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Door Switch > Component Information > Locations > Door Jamb Switch, LH Front
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Door Switch > Component Information > Locations > Door Jamb Switch, LH Front > Page 9273
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Door Switch > Component Information > Locations > Door Jamb Switch, LH Front > Page 9274
Door Switch: Locations Door Jamb Switch, RH Front
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Door Switch > Component Information > Locations > Door Jamb Switch, LH Front > Page 9275
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Door Switch > Component Information > Locations > Door Jamb Switch, LH Front > Page 9276
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Fuel Gauge Sender > Component Information > Locations
Fuel Gauge Sender: Locations
Mounted on Fuel Tank, Part of Fuel Tank Unit
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Fuel Gauge Sender > Component Information > Locations > Page 9280
Fuel Pump/Sender Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Parking Brake Warning Switch > Component Information > Locations > Park Brake Indicator Switch
LH Kick Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Sensors and Switches - Instrument
Panel > Parking Brake Warning Switch > Component Information > Locations > Park Brake Indicator Switch > Page 9285
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control
Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control
Linkage Adjustment > Page 9294
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control
Linkage Adjustment > Page 9295
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > Recalls for Shift Indicator: > 95C61 > Dec > 95 > Recall - A/T Shift Control
Linkage Adjustment > Page 9296
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall A/T Shift Control Linkage Adjustment
Technical Service Bulletin # 95C61 Date: 951201
Recall - A/T Shift Control Linkage Adjustment
No. 95-C-61
Date: 12-01-95
SUBJECT: PRODUCT SAFETY CAMPAIGN 95-C-61 - STEERING COLUMN TRANSMISSION
SHIFT CONTROL ADJUSTMENT
Model and Year: 1995 CAPRICE/IMPALA
To: ALL Chevrolet Dealers
The National Traffic and Motor Vehicle Safety Act, as amended, provides that each vehicle subject
to a recall campaign of this type must be adequately repaired within a reasonable time after the
owner has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is
prima facie evidence of failure to repair within a reasonable time.
If the condition is not adequately repaired within a reasonable time, the owner may be entitled to an
identical or reasonable equivalent vehicle at no charge or to a refund of the purchase price less a
reasonable allowance for depreciation.
To avoid having to provide these burdensome solution, every effort must be made to promptly
schedule an appointment with each owner and to repair their vehicle as soon as possible. As you
will see in reading the included copy of the letter that is being sent to owners, the owners are being
instructed to contact the Chevrolet Customer Assistance Center if their dealer does not remedy the
condition within five (5) days of the mutually agreed upon service date. If the condition is not
remedied within a reasonable time, they are instructed on how to contact The National Highway
Traffic Safety Administration.
Defect & Vehicles Involved
DEFECT INVOLVED
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, "Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the 'park' position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114,
dealers are to perform an adjustment to the shift control linkage system.
VEHICLES INVOLVED
Involved are certain 1995 Chevrolet Caprice/Impala models vehicles built within the VIN
breakpoints as shown.
Involved vehicles have been identified by Vehicle Identification Number Computer Listings.
Computer listings contain the complete Vehicle Identification Number, owner name and address
data, and are furnished to involved dealers with the campaign bulletin. Owner name and address
data furnished will enable dealers to follow-up with owners involved in this campaign
These listings may contain owner names and addresses obtained from State Motor Vehicle
Registration Records. The use of such motor vehicle registration data for any other purpose is a
violation of law in several states. Accordingly, you are urged to limit the use of this listing to the
Follow-up necessary to complete this campaign. Any dealer not receiving a computer listing with
the campaign bulletin has no involved vehicles currently assigned.
Parts Information
No parts are required.
Owner Notification & Dealer Campaign Responsibility
OWNER NOTIFICATION
Owners will be notified of this campaign on their vehicles by Chevrolet Motor Division (see copy of
owner letter included with this bulletin).
DEALER CAMPAIGN RESPONSIBILITY
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall A/T Shift Control Linkage Adjustment > Page 9302
All unsold new vehicles in dealers, possession and subject to this campaign must be held and
inspected/repaired per the service procedure of this campaign bulletin before owners take
possession of these vehicles.
Dealers are to service all vehicles subject to this campaign at no charge to owners, regardless of
mileage, age of vehicle, or ownership, from this time forward.
Owners of vehicles recently sold from your new vehicle inventory with no owner information
indicated on the dealer listing, are to be contacted by the dealer, and arrangements made to make
the required correction according to the instructions contained in this bulletin. This could be done
by mailing to such owners a copy of the letter accompanying this bulletin. Campaign follow-up
cards should not be used for this purpose, since the owner may not as yet have received the
notification letter.
In summary, whenever a vehicle subject to this campaign enters your vehicle inventory or is in your
dealership for service in the future, please take the steps necessary to be sure the campaign
correction has been made before selling or releasing the vehicle.
Service Procedure
NOTE:
The shift linkage must be adjusted each time the transmission is replaced.
1. Place vehicle on hoists. Place steering column range selector in the "N" (neutral) position.
IMPORTANT:
The vehicle must be at the correct trim height for proper linkage adjustment. The vehicle must be
supported by all four (4) tires or by jack stands on the rear axle tube such that the suspension is at
the proper trim height.
2. Loosen screw, automatic transmission range selector rod swivel (Figure 1, Item 816).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall A/T Shift Control Linkage Adjustment > Page 9303
3. Hang a weight (approximately three (3) pounds 1.4 Kilograms) on the end of the steering column
selector lever to bias the selector lever toward but not into the "OD" (overdrive) position. See
Figure 2.
4. Verify that transmission is in "Neutral" position.
5. Tighten screw, automatic transmission range selector rod swivel, (Figure 1, Item 816) to 28 Nm
(21 lb. ft.).
6. Inspect to ensure the steering column selector lever has not moved from the "N" (neutral)
position.
7. Verify the transmission shift control system is properly adjusted.
a. With ignition key removed, while attempting to shift the steering column selector lever from "P"
(park) into the "R" (reverse) position, verify the vehicle will not roll either by placing the vehicle on
an incline or by pushing the vehicle.
NOTE:
If the transmission shift control system is improperly adjusted, the column select lever may not
have been completely out of the "P" (park) position in order for the vehicle to roll.
b. Verify the proper operation of steering column selector lever and transmission in all gear ranges.
If transmission is not functioning properly, repeat steps 1 through 7.
8. Install Campaign Identification Label.
Campaign ID Label and Claim Information
CAMPAIGN IDENTIFICATION LABEL
Each vehicle corrected in accordance with the instructions outlined in this Product Campaign
Bulletin will require a "Campaign Identification Label". Each label provides a space to include the
campaign number and the five (5) digit dealer code of the dealer performing the campaign service.
This information may be inserted with a typewriter or a ball point pen.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > All Technical Service Bulletins for Shift Indicator: > 95C61 > Dec > 95 > Recall A/T Shift Control Linkage Adjustment > Page 9304
Each "Campaign Identification Label" is to be located on the radiator core support in an area which
will be visible when the vehicle is brought in for periodic servicing by the owner. When installing the
new Campaign Identification Label, be sure to install the clear protective covering. Additional
Campaign Identification Labels can be obtained from VISPAC Incorporated by calling
1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when
ordering.
Apply "Campaign Identification Label", only on a clean dry surface.
CLAIM INFORMATION
Submit a Product Campaign Claim with the information indicated as shown.
Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim
Submission.
Owner Letter
Dear Chevrolet Customer:
This notice is sent to you in accordance with the requirements of the National Traffic and Motor
Vehicle Safety Act.
REASON FOR THIS RECALL
General Motors has decided that certain 1995 Chevrolet Caprice/Impala model vehicles fail to
conform to Federal Motor Vehicle Safety Standard (FMVSS) 114, 'Theft protection". Some of these
vehicles have been produced with an improperly adjusted shift control linkage. As a result, it may
be possible to shift from the "park" position with the ignition key removed. This condition may
increase the risk of accidents resulting from unauthorized use or from the unintended movement of
parked vehicles.
WHAT WE WILL DO
To prevent the possibility of this condition occurring, and in order to comply with FMVSS 114, your
dealer will adjust the shift control linkage system. This service will be performed for you at no
charge.
WHAT YOU SHOULD DO
Please contact your Chevrolet dealer as soon as possible to arrange a service date for the repair.
Instruction for making this correction have been sent to your dealer. The labor time necessary to
perform this service correction is approximately 25 minutes. Please ask your dealer if you wish to
know how much additional time will be needed to schedule and process your vehicle.
The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will
assist in making the necessary correction in the shortest possible time. If you have sold or traded
your vehicle, please let us know by completing the postage paid reply card and returning it to us.
Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected
as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service
date, and they do not remedy this condition on that date or within five (5) days, we recommend you
contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020.
After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that
we have done our best to remedy this condition without charge and within a reasonable time, you
may wish to write the administrator, National Highway Traffic Safety Administration, 400 Seventh
Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use
202-366-0123).
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of
your continued satisfaction with our products.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > Page 9305
Shift Indicator: Description and Operation
DESCRIPTION
This lamp is used on most models equipped with manual transmission.
OPERATION
The Upshift lamp is illuminated to inform the driver of ideal shift points, with improved fuel economy
as the specific objective. When the light is illuminated, the transmission should be shifted to the
next highest gear, if driving conditions permit such an action.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Shift Indicator > Component
Information > Technical Service Bulletins > Page 9306
Shift Indicator: Service and Repair
If upshift indicator is not working properly, perform the following test. 1. Disconnect ECM connector
C1. 2. Place ignition switch in run. 3. Measure voltage at terminal A2 of ECM connector. 4. If
battery voltage is present, further ECM diagnosis is necessary. 5. If battery voltage is not present,
repair open circuit in brown/black wire, circuit 456.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Speedometer Head > Component
Information > Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations
Speedometer Head: Technical Service Bulletins Odometer/Speedometer - ACDelco Service Center
Locations
File In Section: 8 - Chassis/Body Electrical
Bulletin No.: 66-83-04A
Date: September, 1996
INFORMATION
Subject: AC Delco Service Center Locations for Odometer/Speedometer Service
Models: 1997 and Prior Passenger Cars and Trucks (excluding Cadillac)
This bulletin is being revised to provide the necessary contact information only. Please discard
Corporate Bulletin Number 66-83-04 (Section 8 - Chassis/Body Electrical)
General Motors provides service for sophisticated electronic products through the authorized AC
Delco Service Center Program. This program is designed to provide GM vehicle owners with the
highest quality and most technically up-to-date product available. Repair products from
unauthorized service outlets are not acceptable as warranty replacements.
Currently, there are 25 authorized AC Delco Service Centers who exchange and remanufacture
odometer/speedometers (list included). Only these Centers should be contacted for service.
Important:
W series and 1997 T series Medium Duty truck odometer/speedometers must be ordered directly
from GMSPO.
The following steps should be taken when utilizing the AC Delco Service Centers: Dealers should
contact their local AC Delco Service Center (list included). Any listed facility may be used.
The following information must be provided:
Part number VIN, Mileage, Vehicle Year, Make and Model Dealer Name and Address Delivery
Date of Vehicle Name of the person requesting exchange or service Phone number Repair Order
Number P.O. number (if non - warranty)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Speedometer Head > Component
Information > Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations > Page 9311
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Speedometer Head > Component
Information > Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations > Page 9312
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Speedometer Head > Component
Information > Technical Service Bulletins > Odometer/Speedometer - ACDelco Service Center Locations > Page 9313
AC Delco Service Centers
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Speedometer Head > Component
Information > Technical Service Bulletins > Page 9314
Speedometer Head: Description and Operation
DESCRIPTION
The Vehicle Speed Sensor (VSS) generates a signal that indicates the vehicle speed. The signal is
processed by the powertrain control module (PCM) to supply inputs to the speedometer and
odometer.
OPERATION
The VSS is mounted in the transaxle and generates an AC voltage signal with a frequency
proportional to vehicle speed. The PCM takes the voltage pulses from the sensor and uses them to
close a solid state output switch. The output terminal is switched to ground at a rate proportional to
vehicle speed. The speedometer and odometer are switched at the same frequency that the sensor
generates at. The speedometer and odometer are operated by a circuit board in the instrument
cluster that converts pulses received from the PCM into a control signal for the vacuum fluorescent
display.
Check for a broken, or partially broken, wire inside the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Speedometer Head > Component
Information > Technical Service Bulletins > Page 9315
Speedometer Head: Testing and Inspection
Fig. 102 Chart 11: Speedometer & Cruise Control Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Temperature Gauge > Component
Information > Description and Operation
Temperature Gauge: Description and Operation
DESCRIPTION
This temperature indicating system consists of a sending unit, located on the cylinder head,
electrical temperature gauge and an instrument voltage regulator.
OPERATION
As engine temperature increases or decreases, the resistance of the sending unit changes, in turn
controlling current flow through the gauge. When engine temperature is low sending unit resistance
is high, current flow through the gauge is restricted, and the gauge pointer remains against the stop
or moves very little. As engine temperature increases sending unit resistance decreases and
current flow through the gauge increases, resulting in increased pointer movement.
Troubleshooting for the electrical temperature indicating system is the same as for the electrical oil
pressure indicating system.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Temperature Gauge > Component
Information > Description and Operation > Page 9319
Temperature Gauge: Testing and Inspection
Fig. 104 Chart 2: Engine Coolant Temperature Gauge Inoperative Or Inaccurate
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Temperature Sensor (Gauge) >
Component Information > Locations
Temperature Sensor (Gauge): Locations
ENGINE COOLANT TEMPERATURE GAUGE SENSOR
Lower Right Side Of Engine
The Engine Coolant Temperature Gauge Sensor is located forward LH side of Engine Block, below
manifold.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Temperature Warning Lamp/Indicator,
Engine Cooling > Component Information > Description and Operation
Temperature Warning Lamp/Indicator: Description and Operation
DESCRIPTION
If the red light is not lit when the engine is being cranked, check for a burned out bulb, an open in
the light circuit, or a defective ignition switch.
If the red light is lit when the engine is running, check the wiring between light and switch for a
ground, temperature switch defective, or overheated cooling system. As a test circuit to check
whether the red bulb is functioning properly, a wire which is connected to the ground terminal of the
ignition switch is tapped into its circuit. When the ignition is in the start engine cranking position, the
ground terminal is grounded inside the switch and the red bulb will be lit. When the engine is
started and the ignition switch is in the on position, the test circuit is opened and the bulb is then
controlled by the temperature switch.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Transmission Shift Position Indicator
Lamp > Component Information > Technical Service Bulletins > Instruments - Reduced PRNDL Display Visibility
Transmission Shift Position Indicator Lamp: Technical Service Bulletins Instruments - Reduced
PRNDL Display Visibility
Bulletin No.: 02-08-42-004A
Date: March 30, 2007
INFORMATION
Subject: PRNDL Display Reduced Visibility For Approximately One Minute
Models: 2007 and Prior Passenger Cars and Trucks (Including Saturn) 2007 and Prior HUMMER
H2, H3 2005-2007 Saab 9-7X
with Automatic Headlamp Control and Vacuum Fluorescent PRNDL Indicator Instrument Panel
Cluster
Supercede:
This bulletin is being revised to include additional models and model years. Please discard
Corporate Bulletin Number 02-08-42-0004 (Section 08 - Body and Accessories).
After backing the vehicle out of a garage or dark environment into a daylight environment, the
PRNDL display has reduced visibility for approximately one minute.
While the vehicle is parked in a dark environment, the sensor for the automatic headlamp/driving
lamps senses that it is dark. When the key is turned to the run/start position, the automatic
headlamp module will turn all driving lamps, the instrument panel cluster and PRNDL display ON in
the night-time mode. The night-time mode intensity of the instrument panel lamps and PRNDL
display is controlled by the automatic headlamp module and can be dimmed further by the
customer using the dimming control of the headlamp switch.
When the customer then moves the vehicle from the dark environment into the bright sunlight, it will
take approximately one minute before the headlamp control module recognizes this as true daylight
and not just a bright overhead street lamp shining on the sensor. The headlamp control module will
then turn the headlamps off and restore the instrument panel and PRNDL display to full brilliance.
Without the time delay, the automatic headlamp control module would switch to the night mode
(turn on all driving lamps, instrument panel lamps and PRNDL display would dim) each time the
vehicle was driven under an overpass or other darkened environment.
This is a normal condition and no repair should be attempted.
Ensure the instrument panel backlighting control is in the full bright position. This will help alleviate
the condition. You may demonstrate to the customer what happens by placing a repair order over
the automatic headlamp control light sensor, which will cause the automatic headlamp control
module to switch to the night mode in approximately one minute. All driving lamps will come ON,
the instrument panel backlight will be dim, and the PRNDL display will also dim to the night setting
in conjunction with the position of the headlamp switch dimming control. Demonstrate to the
customer the variance in the instrument panel backlighting and PRNDL display while adjusting the
headlamp switch dimming control to both ends of its allowable range. Advise the customer to keep
the headlight switch dimming control in the highest position to allow viewing of the PRNDL display
in a bright environment.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Description and Operation
Volt Meter Gauge: Description and Operation
DESCRIPTION
The voltmeter is a gauge which measures the electrical flow from the battery to indicate whether
the battery output is within tolerances. The voltmeter reading can range from 13.5-14.0 volts under
normal operating conditions. If an undercharge or overcharge condition is indicated for an extended
period, the battery and charging system should be checked.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview
Volt Meter Gauge: Initial Inspection and Diagnostic Overview
Circuit Operation - Starter
Battery voltage is applied to the Ignition Switch at all times through Maxifuse 11. When the Ignition
Switch is turned to "START" battery voltage is applied through the closed contacts of the Ignition
Switch, (through the contacts of the Theft Deterrent Relay. This relay is controlled by the Theft
Deterrent Module, (NON SEO)). Then it goes to the Starter Solenoid at terminal "S". When battery
voltage is applied to terminal "S" of the Starter Solenoid Switch, the Hold-In Coil and Pull-In Coil of
the Starter Solenoid switch are energized with the Pull-In Coil grounded through the Starter Motor.
The coils, when energized, work together to pull in and hold the Plunger of the Starter Solenoid
switch. As the Plunger is pulled in, it closes the Starter Solenoid Switch contacts and causes the
Shift Lever to rotate, engaging the Drive Assembly to the Flywheel. With battery voltage applied
directly to the Starter Motor through the closed Solenoid Contacts, the Starter Motor begins to
rotate the Drive Assembly as the Drive Assembly comes in contact with the Flywheel. The Pull-In
Coil is de-energized by having battery voltage at both ends of the coil. The Starter Motor continues
to rotate to crank the Engine through the Drive Assembly-Flywheel gear combination. Battery
voltage is removed from the Starter Solenoid terminal "S" when the Ignition Switch is released from
the "START" position. The Hold-In Coil is de-energized and the return spring in the Starter
Solenoid Switch causes the Plunger to disengage the Drive Assembly from the Flywheel. As the
Plunger returns, the Plunger opens the Solenoid Contacts removing battery voltage from the
Starter Motor.
Circuit Operation - Charging
The Generator provides voltage to operate the vehicle's electrical system and charge the Battery.
The Regulator supplies current to the field coil of the Rotor. When current flows through the field
coil, a magnetic field is created. This field rotates as the Rotor is driven by the Engine, creating an
AC voltage and current in the Stator windings. This AC signal is converted to DC by the rectifier
bridge and available to the vehicle's electrical system at the "BAT" terminal. The Generator must
supply sufficient current to all vehicle electrical loads especially for charging the vehicle's Battery.
Since the Rotor speed varies with Engine speed, the Generator must also maintain the output
voltage at a constant value. The Generator's Regulator switches current to the field coil of the
Rotor on or off controlling the output voltage of the Generator. When the Ignition Switch is turned to
"RUN," battery voltage is supplied from U/Hood Fuse #8 to the Generator at terminal "F", turning
on the Regulator. If for any reason terminal "F" did not supply any current to the connection inside
the Generator, the Regulator could still turn on because CKT 25 would function as a backup source
of "TURN ON" current.
The Regulator switches on the field current by connecting the field coil of the Rotor to battery
voltage available at the "BAT" terminal. The field current creates a weak magnetic field in the field
coil when the Engine is being started. The Regulator senses Generator rotation by detecting an AC
voltage at the Stator through an internal wire. Once the Engine is running, the Regulator can
monitor the internal AC voltage and DC output at the " BAT" terminal. The Regulator will then vary
the current in the field coil of the Rotor as needed, to provide a constant output voltage and
adequate current to the electrical system of the vehicle.
Circuit Operation - Check Gage Indicator
Battery voltage is applied to the Instrument Cluster through I/P Fuse #11 whenever the Ignition
Switch is in "RUN," or "START." A ground is provided at the Generator "L" terminal when the
Regulator senses a high or low voltage condition or when the Rotor stops turning.
Troubleshooting Hints - Charging System
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Visually inspect the hydrometer (built into Battery).
^ Green dot - Battery is charged.
^ Dark dot - Charge and load test Battery. If Battery passes load test, refer to System Diagnosis.
See: Starting and Charging/Testing and Inspection/Initial Inspection and Diagnostic
Overview/Preliminary Information - Starting System
^ Clear or light yellow dot - Battery electrolyte is low. Replace Battery.
2. Check U/Hood Fuse #8 and I/P Fuse #11. Check Maxifuse 11. 3. Check that the Generator
Connector and Generator "BAT" terminal are both clean and tight. 4. Check that the Battery
connections are clean and tight. 5. Check Generator belt. ^
Check for a broken (or partially broken) wire inside of the insulation which could cause system
failure but prove "GOOD" in a continuity/voltage check (refer to "General Troubleshooting
Procedures,"). See: Diagrams/Diagnostic Aids
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,").
^ Refer to System Diagnosis.
Troubleshooting Hints - Starter
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Visually inspect the hydrometer (built into Battery).
^ Green dot - Battery is charged.
^ Dark dot - Charge and load test Battery.If Battery passes load test, refer to System Diagnosis.
See: Starting and Charging/Testing and Inspection/Initial Inspection and Diagnostic
Overview/Preliminary Information - Starting System
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9335
^ Clear or light yellow dot - Battery electrolyte is low. Replace Battery.
2. Check that Starter Solenoid Switch terminals "S" and B" and Battery connections are clean and
tight. 3. Check that Maxifuse #11 and I/P Fuse #24 are OK. If these fuses are open, check for a
short to ground in CKT 5, CKT 142 or CKT 806. 4. Check that G100 and G101 are clean and tight.
^
Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational (under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
^ Refer to System Diagnosis.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9336
Volt Meter Gauge: Symptom Related Diagnostic Procedures
Symptom Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9337
Chart #1 Engine Does Not Crank, Starter Solenoid Switch Does Not Click
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9338
Chart #2 Starter Solenoid Switch Click, Engine Does Not Crank
Chart #3 Battery Is Undercharged Or Overcharged
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9339
Chart #4 VOLTS Or CHECK GAGE Indicator ON At All Times
Chart #5 VOLTS Or CHECK GAGE Indicator Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Instrument Panel, Gauges and Warning Indicators > Volt Meter Gauge > Component
Information > Testing and Inspection > Initial Inspection and Diagnostic Overview > Page 9340
Volt Meter Gauge: Component Tests and General Diagnostics
To test meter, turn key and headlights On with engine Off. Pointer should move to 12.5 volts. If no
needle movement is observed, check connections from battery to circuit breaker. If connections are
tight and meter shows no movement, check wire continuity. If wire continuity is satisfactory, the
meter is inoperative and must be replaced.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Ambient Light Sensor > Component Information > Locations
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Backup Lamp > Backup Lamp Switch > Component Information >
Locations
Backup Lamp Switch: Locations
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Backup Lamp > Backup Lamp Switch > Component Information >
Locations > Page 9349
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Technical Service Bulletins >
Lighting - Exterior Lamp Condensation and Replacement
Brake Lamp: Technical Service Bulletins Lighting - Exterior Lamp Condensation and Replacement
INFORMATION
Bulletin No.: 01-08-42-001H
Date: January 05, 2011
Subject: Exterior Lamp Condensation and Replacement Guidelines
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn)
Supercede: This bulletin is being revised to add the 2011 model year. Please discard Corporate
Bulletin Number 01-08-42-001G (Section 08 - Body and Accessories).
The following information is being provided to better define the causes of condensation in exterior
lamps and includes guidelines for determining the difference between a lamp with a normal
atmospheric condition (condensation) and a lamp with a water leak.
Some exterior lamps, such as cornering, turn signal, backup, headlamps or tail lamps may exhibit
very small droplets of water, a fine mist or white fog (condensation) on the inside of the lamp lens.
This may be more noticeable on lamps with "multi-lens" designs and may be normal during certain
weather conditions.
Condensation occurs when the air inside the lamp assembly, through atmospheric changes,
reaches the "dew point". When this takes place, the moisture in the air within the lamp assembly
condenses, creating a fine mist or white fog on the inside surface of the lamp lens.
Most exterior lamps on General Motors vehicles use a vented design and feature a replaceable
bulb assembly. They are designed to remove any accumulated moisture vapor by expelling it
through a vent system. The vent system operates at all times, however, it is most effective when
the lamps are ON or when the vehicle is in motion. Depending on the size, shape and location of
the lamp on the vehicle, and the atmospheric conditions occurring, the amount of time required to
clear the lamp may vary from 2 to 6 hours.
Completely sealed headlamp assemblies (sealed beams) are still used on a limited number of
models being manufactured today. These lamps require the replacement of the complete lamp
assembly if a bulb filament burns out.
Condensation 2006 TrailBlazer Shown
A Fine Mist or White Fog on the Inside Surface of the Lamp Lens Occurring After a Period of High
Humidity
- May be located primarily in the lens corners (near the vents) and SHOULD NOT cover more than
half the lens surface.
- The condition should clear of moisture when the vehicle is parked in a dry environment, or when
the vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a SIMILAR
performance.
If the above conditions are noted, the customer should be advised that replacement of a lamp
assembly may not correct this condition.
Water Leak New Style Pickup Shown
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Technical Service Bulletins >
Lighting - Exterior Lamp Condensation and Replacement > Page 9354
Numerous & Various Size Drops of Water Collecting on the Inside Surface of the Lamp Lens After
the Vehicle Has Been Exposed to Rain or a Car Washing Environment
- A condition that covers more than half the surface of the lamp lens.
- An accumulation of water in the bottom of the lamp assembly.
- A condition that WON'T clear when the vehicle is parked in a dry environment, or when the
vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a different
performance.
Any of the above conditions would indicate the need to service the lens or lamp assembly.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Locations > Inboard
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Locations > Inboard > Page
9357
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Locations > Inboard > Page
9358
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Locations > Inboard > Page
9359
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Lamp > Component Information > Locations > Page 9360
Brake Lamp: Description and Operation
Voltage is applied at all times from I/P Fuse #37 to the Stoplamp Switch. When the brake pedal is
depressed, voltage is applied from the Stoplamp Switch and Turn Signal Switch to CKT 18 and
CKT 19, turning "ON" the LH and RH Tail/Stop/Turn Lamps.
Voltage is supplied at all times through I/P Fuse #37 to the Stoplamp/Cruise Release Switch. When
the brake pedal is depressed, voltage is applied from the Stoplamp/Cruise Release Switch to CKT
17 and the High Mount Stoplamp, turning "ON" the High Mount Stoplamp.
Buick Wagons with Remote Keyless Entry (AUO) have a 400 ohm resistor in CKT 17 and CKT 750.
This Resistor is used to prevent accidental locking of the door locks in cases where the Hazard
Switch has been activated and the rear glass is released. Residual voltage in CKT 17 could cause
the Remote Control Door Lock Receiver to activate a Door Lock Cycle. The 400 ohm resistor will
keep CKT 17 "LOW," thus preventing an unwanted Lock Cycle. Refer to Keyless Entry for
additional information on the Remote Keyless Entry System. See: Accessories and Optional
Equipment/Antitheft and Alarm Systems/Remote Keyless Entry
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Light Switch > Component Information > Locations
Brake Light Switch: Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Light Switch > Component Information > Locations > Page
9364
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Brake Light Switch > Component Information > Locations > Page
9365
Brake Light Switch: Service and Repair
The stop light switch has a slip fit in the mounting sleeve which permits positive adjustment by
pulling the brake pedal up firmly against the stop. The pedal arm forces the switch body to slip in
the mounting sleeve bushing to position the switch properly.
1. Disconnect wires from switch and remove switch from bracket. 2. Position replacement switch in
bracket and push inward until fully seated. Brake pedal arm moves switch to correct distance on
rebound. Check if
pedal is in full return position by lifting slightly by hand.
3. Connect switch electrical connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions
Center Mounted Brake Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9370
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9371
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9372
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9373
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9374
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9375
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9376
Center Mounted Brake Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Center Mounted Brake Lamp > Component Information > Diagrams >
Diagram Information and Instructions > Page 9377
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Diagram Information and Instructions > Page 9378
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Diagram Information and Instructions > Page 9379
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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Diagram Information and Instructions > Page 9380
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Diagram Information and Instructions > Page 9395
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Diagram Information and Instructions > Page 9396
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Diagram Information and Instructions > Page 9397
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Diagram Information and Instructions > Page 9398
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Diagram Information and Instructions > Page 9399
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Diagram Information and Instructions > Page 9400
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Diagram Information and Instructions > Page 9401
Center Mounted Brake Lamp: Electrical Diagrams
Turn/Stop/Hazard/High Mount Stop
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Diagram Information and Instructions > Page 9402
Turn/Stop/Hazard/High Mounted Stop/Front Marker/Park/License
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Coach Lamp > Component Information > Locations > Opera Lamp
Coach Lamp: Locations Opera Lamp
LH
Outside LH "C" Pillar
RH
Outside RH "C" Pillar
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Page 9407
Coach Lamp: Locations Spot Lamp (Seo)
LH
At LH "A" Pillar
RH
At RH "A" Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Locations > Component
Locations
Cornering Lamp: Component Locations
LH Forward Lamp Wiring
RH Forward Engine Compartment
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Locations > Page 9412
Cornering Lamp: Connector Locations
Base Of Steering Column
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Locations > Page 9413
RH Side Of Steering Column
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Information and Instructions
Cornering Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Information and Instructions > Page 9419
Fig.2-Symbols (Part 2 Of 3)
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Information and Instructions > Page 9420
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Cornering Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9442
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9443
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9444
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9445
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9446
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9447
Cornering Lights
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Diagrams > Page 9448
Cornering Lamp: Description and Operation
Voltage is applied to the Headlamp Switch at all times. With the Headlamp Switch in "PARK" or
"HEAD," voltage is applied to the Cornering Lamps Switch, which is part of the Turn/Signal Switch
Assembly. With the Turn Signal Switch in either the "TURN LEFT" or "TURN RIGHT" position,
voltage is supplied to the corresponding Front Sidemarker and Cornering Lamp. Both Lamps are
permanently grounded, the LH Lamp to G102 and the RH Lamp to G106.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Testing and Inspection >
Initial Inspection and Diagnostic Overview
Cornering Lamp: Initial Inspection and Diagnostic Overview
Circuit Operation
Voltage is applied to the Headlamp Switch at all times. With the Headlamp Switch in "PARK" or
"HEAD," voltage is applied to the Cornering Lamps Switch, which is part of the Turn/Signal Switch
Assembly. With the Turn Signal Switch in either the "TURN LEFT" or "TURN RIGHT" position,
voltage is supplied to the corresponding Front Sidemarker and Cornering Lamp. Both Lamps are
permanently grounded, the LH Lamp to G102 and the RH Lamp to G106.
Troubleshooting Hints
PERFORM BEFORE BEGINNING SYSTEM DIAGNOSIS:
1. Check I/P Fuse #31. If it is open, check CKT 240 for a short to ground. 2. Check I/P Fuse #41. If
it is open, check CKT 308 for a short to ground and Refer to Exterior Lights for Diagnosis of Park
Lamps. See: Testing
and Inspection
3. Make sure that G102 and G106 are clean and tight. 4. Check bulbs and sockets for damage or
corrosion. ^
Check for a broken (or partially broken) wire inside of the insulation which could cause system
malfunction but prove G00D in a continuity/voltage check with a system disconnected. These
circuits may be intermittent or resistive when loaded, and if possible, should be checked by
monitoring for a voltage drop with the system operational under load).
^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of
other systems (refer to "General Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids
^ Refer to System Diagnosis. See: Component Tests and General Diagnostics/System Diagnosis
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Testing and Inspection >
Initial Inspection and Diagnostic Overview > Page 9451
Cornering Lamp: Component Tests and General Diagnostics
Chart #1 Both Cornering Lamps Are Inoperative, Park Lamps Operate
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Testing and Inspection >
Initial Inspection and Diagnostic Overview > Page 9452
Chart #2 One Cornering Lamp Is Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Cornering Lamp > Component Information > Testing and Inspection >
Initial Inspection and Diagnostic Overview > Page 9453
Chart #3 One Cornering Lamp Is ON Whenever Park Lamps Are Activated
Symptom Table
System Diagnosis
^ Refer the Symptom Table for the appropriate diagnostic procedure(s). See: Symptom Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Ash Tray Lamp > Component Information >
Locations
Front Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Courtesy Lamp Relay > Component Information >
Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Door Lamp > Component Information > Locations >
Courtesy Lamp, Front Door
Door Lamp: Locations Courtesy Lamp, Front Door
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Door Lamp > Component Information > Locations >
Courtesy Lamp, Front Door > Page 9465
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Door Lamp > Component Information > Locations >
Courtesy Lamp, Front Door > Page 9466
Door Lamp: Locations Door Handle Lamp
LH
LH Front Door
RH
RH Front Door
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Door Lamp > Component Information > Locations >
Courtesy Lamp, Front Door > Page 9467
Door Lamp: Locations Door Lock Switch Lamp
LH
LH Front door
RH
RH Front Door
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Courtesy Lamp > Glove Box Lamp > Component Information >
Locations
Back View Of RH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Daytime Running Lamp > Daytime Running Lamp Control Unit >
Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Daytime Running Lamp > Daytime Running Lamp Control Unit >
Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 9476
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Daytime Running Lamp > Daytime Running Lamp Control Unit >
Component Information > Locations > Page 9477
Daytime Running Lamp Control Unit: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Daytime Running Lamp > Daytime Running Lamp Diode Assembly >
Component Information > Locations
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Daytime Running Lamp > Daytime Running Lamp Relay >
Component Information > Diagrams
Theft Deterrent Relay Daytime Running Lamps (DRL) Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Dimmer Switch > Component Information > Technical Service
Bulletins > IP Dimmer Control - Proper Setting
Dimmer Switch: Technical Service Bulletins IP Dimmer Control - Proper Setting
File In Section: 08 - Body and Accessories
Bulletin No.: 99-08-42-009
Date: November, 1999
INFORMATION
Subject: Proper Setting of I/P Dimmer Control to View PRNDL Display with Automatic Headlamp
Control
Models: 2000 and Prior All Passenger Cars and Trucks With Automatic Headlamp Control and
Electronic PRNDL Display
Under certain conditions, if the instrument panel dimmer control is turned relatively low, the PRNDL
will not be visible until the automatic headlamp control turns the headlamps off and the daytime
running lamps (DRL) are turned back on. Such a condition may be if the vehicle is first started in an
environment where the headlamp control turns on the headlamps and then the vehicle is driven out
into a brighter environment (for example, when a vehicle is backed out of a dark garage into the
bright sunlight).
This condition is normal and any repair attempt will not be successful. Demonstrate this condition
to the customer using the service lane and then turn the instrument panel dimmer control to a
higher setting. This will enable the driver to see the PRNDL display
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Dimmer Switch > Component Information > Locations > Component
Locations
Dimmer Switch: Component Locations
Lower LH Side Of Steering Column
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Dimmer Switch > Component Information > Locations > Component
Locations > Page 9490
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Dimmer Switch > Component Information > Locations > Page 9491
Dimmer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Dimmer Switch > Component Information > Locations > Page 9492
Dimmer Switch: Service and Repair
Fig. 13 Column Mounted Dimmer Switch Installation
1. Disconnect battery ground cable. 2. Remove instrument panel lower trim and on models with
A/C, remove A/C duct extension at column. 3. Disconnect shift indicator from column and remove
toe-plate cover screws. 4. Remove two nuts from instrument panel support bracket studs and lower
steering column, resting steering wheel on front seat. 5. Remove dimmer switch retaining screws,
then the switch. Tape actuator rod to column and separate switch from rod. 6. Reverse procedure
to install. To adjust switch, depress dimmer switch slightly and install a 3/32 inch twist drill to lock
switch to the body, Fig. 13.
Force switch upward to remove lash between switch and pivot, then remove tape from actuator
rod. Remove twist drill and check for proper operation.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Dome Lamp > Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Door Switch > Component Information > Locations > Door Jamb
Switch, LH Front
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Door Switch > Component Information > Locations > Door Jamb
Switch, LH Front > Page 9500
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Door Switch > Component Information > Locations > Door Jamb
Switch, LH Front > Page 9501
Door Switch: Locations Door Jamb Switch, RH Front
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Door Switch > Component Information > Locations > Door Jamb
Switch, LH Front > Page 9502
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Door Switch > Component Information > Locations > Door Jamb
Switch, LH Front > Page 9503
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Hazard Warning Lamps > Hazard Warning Flasher > Component
Information > Locations
Hazard Warning Flasher: Locations
Mounted On HVAC Module
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Control Module > Component Information >
Locations > Daytime Running Lamp (DRL)/Twilight Module
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Control Module > Component Information >
Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 9513
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Control Module > Component Information >
Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 9514
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Control Module > Component Information >
Locations > Page 9515
Headlamp Control Module: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Control Module > Component Information >
Locations > Page 9516
Headlamp Control Module (C2)
C406: Body Harness To Tailgate Harness, Headlamp Automatic Control Module (C1), Remote
Control Door Lock Receiver
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Dimmer Switch > Component Information >
Locations
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Lens > Component Information > Technical
Service Bulletins > Lighting - Headlamp Polycarbonate Lens Damage Prevention
Headlamp Lens: Technical Service Bulletins Lighting - Headlamp Polycarbonate Lens Damage
Prevention
INFORMATION
Bulletin No.: 02-08-42-001D
Date: June 21, 2010
Subject: Headlamp Lens Overheating When Covered and Chemical Damage to Exterior
Polycarbonate Headlamp Lenses
Models:
2011 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2,
H3 2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add model years and to revise the warning statements.
Please discard Corporate Bulletin Number 02-08-42-001C (Section 08 - Body and Accessories).
The bulletin is being issued to make dealers and customers aware of chemical damage that may
be caused to exterior polycarbonate headlamp lenses. Most late model vehicles have these types
of headlamp lenses. This material is used because of its temperature and high impact resistance.
A variety of chemicals can cause crazing or cracking of the headlamp lens. Headlamp lenses are
very sensitive. Care should be exercised to avoid contact with all exterior headlamp lenses when
treating a vehicle with any type of chemical, such as those recommended for rail dust removal.
Rubbing compound, grease tar and oil removers, tire cleaners, cleaner waxes and even car wash
soaps in too high a concentration may also attribute to this condition. This could result in the need
to replace the entire headlamp housing.
Warning
Use only lukewarm or cold water, a soft cloth and a car washing soap to clean exterior lamps and
lenses.
Also, crazing or deformations of the lens may occur if a shop mat or fender cover is draped over
the fender and covers a portion or all of the headlamp assembly while the DRL or headlamps are
on. This action restricts the amount of heat dissipated by the headlamps.
Warning
Care should be taken to not cover headlamps with shop mats or fender covers if the vehicle is
being serviced with the headlamps or DRL illuminated. Covering an illuminated lamp can cause
excessive heat build up and crazing/deformation of the lens may occur. The degradation of the lens
can be unnoticeable at first and eventually become hairline cracks in the lens. In extreme cases, it
could cause the lens to deform. This damage can also be caused by aftermarket shields that are
often tinted in color.
Once a heat buildup is generated by the headlamp, a degradation of the headlamp lens begins.
This degradation of the lens can be unnoticeable at first and eventually manifest as spider cracks.
In more extreme cases, it will begin to melt the lens of the headlamp.
Notice
Headlamps damaged by chemicals, improper cleaning, or overheating due to being covered are
not covered under the new vehicle warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Switch > Component Information > Locations
> Twilight Sentinel Connector
Twilight Sentinel Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Switch > Component Information > Locations
> Twilight Sentinel Connector > Page 9528
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Switch > Component Information > Locations
> Twilight Sentinel Connector > Page 9529
Headlamp Switch: Locations Twilight Sentinel/Daytime Running Lamps Harness
Back View Of RH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Switch > Component Information > Locations
> Twilight Sentinel Connector > Page 9530
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Switch > Component Information > Locations
> Page 9531
Headlamp Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Headlamp > Headlamp Switch > Component Information > Locations
> Page 9532
Headlamp Switch: Service and Repair
Fig. 7 Headlamp Switch Replacement
1. Disconnect battery ground cable. 2. Remove lower steering column trim panel attaching screws,
then pull downward to remove. 3. Through glove compartment, unsnap righthand molding. 4.
Loosen steering column support bracket to instrument panel carrier attaching bolts. Do not remove
bolts. 5. Gently lower steering column assembly. Use extreme care when lowering steering to
prevent damage to column assembly. 6. Remove lefthand trim plate to instrument panel carrier
assembly six attaching screws, then unsnap lefthand trim assembly. 7. Remove headlamp switch
attaching screws. 8. Pull switch rearward, then disconnect switch electrical connectors and remove,
Fig. 7. 9. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Horn > Horn Relay > Component Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Horn > Horn Switch > Component Information > Locations
Steering Wheel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > License Plate Lamp > Component Information > Locations
Trunk Lid
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > License Plate Lamp > Component Information > Diagrams > Diagram
Information and Instructions
License Plate Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > License Plate Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9545
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > License Plate Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9546
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > License Plate Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9547
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > License Plate Lamp > Component Information > Diagrams > Diagram
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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License Plate Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Information and Instructions > Page 9564
Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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Information and Instructions > Page 9566
If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Information and Instructions > Page 9567
Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Information and Instructions > Page 9568
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Information and Instructions > Page 9569
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information and Instructions > Page 9570
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Information and Instructions > Page 9571
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Information and Instructions > Page 9572
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information and Instructions > Page 9573
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Information and Instructions > Page 9574
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information and Instructions > Page 9575
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information and Instructions > Page 9576
License Plate Lamp: Electrical Diagrams
Front Marker/Hazard/Park/Turn/License
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Information and Instructions > Page 9577
Turn/Stop/Hazard/High Mounted Stop/Front Marker/Park/License
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Information and Instructions > Page 9578
Tail/Rear Marker/License
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9579
License Plate Lamp: Description and Operation
Voltage is applied at all times from I/P Fuse #31 to the Headlamp Switch and, if equipped, to the
Automatic Headlamp Control or Daytime Running Lamp (DRL) Module from CKT 240. With the
Headlamp Switch in "PARK" or "HEAD" or with low light conditions, if equipped with Twilight
Sentinel, voltage is applied to CKT 9. Current flows through CKT 9, to I/P Fuse Block, which feeds
all Park, Marker, Tail and License Lamps turning them "ON." The only lamps that see a current
from CKT 308 and do not turn "ON," are the turn filaments in the Park/Turn Lamps. They do not
activate because the voltage drop across the Front Side Marker Lamps is much higher than that
across the Turn Lamp Filaments.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Map Light > Component Information > Locations > RH
RH Hood Rail
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Chevrolet Workshop Manuals > Lighting and Horns > Map Light > Component Information > Locations > RH > Page 9584
Front Headliner
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Marker Lamp > Component Information > Locations > Marker Lamp,
Rear
Marker Lamp: Locations Marker Lamp, Rear
LH
LH Rear of Vehicle
RH
RH Rear of Vehicle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Marker Lamp > Component Information > Locations > Marker Lamp,
Rear > Page 9589
Marker Lamp: Locations Park and Side Marker Lamp, Front
LH Forward Lamp Wiring
RH Forward Engine Compartment
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Rear > Page 9590
LH Forward Lamp Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Marker Lamp > Component Information > Locations > Marker Lamp,
Rear > Page 9591
Marker Lamp: Locations Side Marker Lamp, LH Rear
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Rear > Page 9592
Rear Lamps
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Chevrolet Workshop Manuals > Lighting and Horns > Marker Lamp > Component Information > Locations > Marker Lamp,
Rear > Page 9593
Marker Lamp: Locations
LH
LH Rear of Vehicle
RH
RH Rear of Vehicle
LH Forward Lamp Wiring
RH Forward Engine Compartment
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Marker Lamp > Component Information > Locations > Marker Lamp,
Rear > Page 9594
LH Forward Lamp Wiring
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Marker Lamp > Component Information > Locations > Marker Lamp,
Rear > Page 9595
Rear Lamps
RH Forward Engine Compartment
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Rear > Page 9596
Rear Lamps
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Information and Instructions
Marker Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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Information and Instructions > Page 9599
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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Information and Instructions > Page 9600
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Marker Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Information and Instructions > Page 9623
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Information and Instructions > Page 9624
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Information and Instructions > Page 9625
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Information and Instructions > Page 9626
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Information and Instructions > Page 9627
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information and Instructions > Page 9629
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information and Instructions > Page 9630
Marker Lamp: Electrical Diagrams
Front Marker/Hazard/Park/Turn/License
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Information and Instructions > Page 9631
Turn/Stop/Hazard/High Mounted Stop/Front Marker/Park/License
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Information and Instructions > Page 9632
Tail/Rear Marker/License
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Marker Lamp: Description and Operation
Voltage is applied at all times from I/P Fuse #31 to the Headlamp Switch and, if equipped, to the
Automatic Headlamp Control or Daytime Running Lamp (DRL) Module from CKT 240. With the
Headlamp Switch in "PARK" or "HEAD" or with low light conditions, if equipped with Twilight
Sentinel, voltage is applied to CKT 9. Current flows through CKT 9, to I/P Fuse Block, which feeds
all Park, Marker, Tail and License Lamps turning them "ON." The only lamps that see a current
from CKT 308 and do not turn "ON," are the turn filaments in the Park/Turn Lamps. They do not
activate because the voltage drop across the Front Side Marker Lamps is much higher than that
across the Turn Lamp Filaments.
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Chevrolet Workshop Manuals > Lighting and Horns > Parking Lamp > Component Information > Technical Service Bulletins
> Lighting - Exterior Lamp Condensation and Replacement
Parking Lamp: Technical Service Bulletins Lighting - Exterior Lamp Condensation and
Replacement
INFORMATION
Bulletin No.: 01-08-42-001H
Date: January 05, 2011
Subject: Exterior Lamp Condensation and Replacement Guidelines
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn)
Supercede: This bulletin is being revised to add the 2011 model year. Please discard Corporate
Bulletin Number 01-08-42-001G (Section 08 - Body and Accessories).
The following information is being provided to better define the causes of condensation in exterior
lamps and includes guidelines for determining the difference between a lamp with a normal
atmospheric condition (condensation) and a lamp with a water leak.
Some exterior lamps, such as cornering, turn signal, backup, headlamps or tail lamps may exhibit
very small droplets of water, a fine mist or white fog (condensation) on the inside of the lamp lens.
This may be more noticeable on lamps with "multi-lens" designs and may be normal during certain
weather conditions.
Condensation occurs when the air inside the lamp assembly, through atmospheric changes,
reaches the "dew point". When this takes place, the moisture in the air within the lamp assembly
condenses, creating a fine mist or white fog on the inside surface of the lamp lens.
Most exterior lamps on General Motors vehicles use a vented design and feature a replaceable
bulb assembly. They are designed to remove any accumulated moisture vapor by expelling it
through a vent system. The vent system operates at all times, however, it is most effective when
the lamps are ON or when the vehicle is in motion. Depending on the size, shape and location of
the lamp on the vehicle, and the atmospheric conditions occurring, the amount of time required to
clear the lamp may vary from 2 to 6 hours.
Completely sealed headlamp assemblies (sealed beams) are still used on a limited number of
models being manufactured today. These lamps require the replacement of the complete lamp
assembly if a bulb filament burns out.
Condensation 2006 TrailBlazer Shown
A Fine Mist or White Fog on the Inside Surface of the Lamp Lens Occurring After a Period of High
Humidity
- May be located primarily in the lens corners (near the vents) and SHOULD NOT cover more than
half the lens surface.
- The condition should clear of moisture when the vehicle is parked in a dry environment, or when
the vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a SIMILAR
performance.
If the above conditions are noted, the customer should be advised that replacement of a lamp
assembly may not correct this condition.
Water Leak New Style Pickup Shown
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Numerous & Various Size Drops of Water Collecting on the Inside Surface of the Lamp Lens After
the Vehicle Has Been Exposed to Rain or a Car Washing Environment
- A condition that covers more than half the surface of the lamp lens.
- An accumulation of water in the bottom of the lamp assembly.
- A condition that WON'T clear when the vehicle is parked in a dry environment, or when the
vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a different
performance.
Any of the above conditions would indicate the need to service the lens or lamp assembly.
Disclaimer
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LH Forward Lamp Wiring
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9641
RH Forward Engine Compartment
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Information and Instructions
Parking Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
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GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
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The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
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Fig.1-Symbols (Part 1 Of 3)
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Fig.2-Symbols (Part 2 Of 3)
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Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
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Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
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Parking Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
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Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
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DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
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Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
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Information and Instructions > Page 9667
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
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Information and Instructions > Page 9668
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
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Information and Instructions > Page 9669
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
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Information and Instructions > Page 9670
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
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Information and Instructions > Page 9671
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
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Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
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Information and Instructions > Page 9673
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
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Information and Instructions > Page 9674
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
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Information and Instructions > Page 9675
Parking Lamp: Electrical Diagrams
Front Marker/Hazard/Park/Turn/License
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Information and Instructions > Page 9676
Turn/Stop/Hazard/High Mounted Stop/Front Marker/Park/License
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Parking Lamp: Description and Operation
Voltage is applied at all times from I/P Fuse #31 to the Headlamp Switch and, if equipped, to the
Automatic Headlamp Control or Daytime Running Lamp (DRL) Module from CKT 240. With the
Headlamp Switch in "PARK" or "HEAD" or with low light conditions, if equipped with Twilight
Sentinel, voltage is applied to CKT 9. Current flows through CKT 9, to I/P Fuse Block, which feeds
all Park, Marker, Tail and License Lamps turning them "ON." The only lamps that see a current
from CKT 308 and do not turn "ON," are the turn filaments in the Park/Turn Lamps. They do not
activate because the voltage drop across the Front Side Marker Lamps is much higher than that
across the Turn Lamp Filaments.
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Component Information > Locations
Convenience Center
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Chevrolet Workshop Manuals > Lighting and Horns > Relays and Modules - Lighting and Horns > Daytime Running Lamp
Control Unit > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module
RH Front Door And A Pillar
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Control Unit > Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 9686
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Control Unit > Component Information > Locations > Page 9687
Daytime Running Lamp Control Unit: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Relay > Component Information > Diagrams
Theft Deterrent Relay Daytime Running Lamps (DRL) Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Relays and Modules - Lighting and Horns > Headlamp Control Module
> Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module
RH Front Door And A Pillar
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Chevrolet Workshop Manuals > Lighting and Horns > Relays and Modules - Lighting and Horns > Headlamp Control Module
> Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 9695
RH Lower Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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> Component Information > Locations > Daytime Running Lamp (DRL)/Twilight Module > Page 9696
Center Of Instrument Panel Wiring
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> Component Information > Locations > Page 9697
Headlamp Control Module: Diagrams
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C2
DRL Control Module, Keyless Entry Receiver & Twilight Sentinel Module: C1
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> Component Information > Locations > Page 9698
Headlamp Control Module (C2)
C406: Body Harness To Tailgate Harness, Headlamp Automatic Control Module (C1), Remote
Control Door Lock Receiver
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Information > Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Ambient Light Sensor >
Component Information > Locations
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Backup Lamp Switch >
Component Information > Locations
Backup Lamp Switch: Locations
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Backup Lamp Switch >
Component Information > Locations > Page 9709
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Brake Light Switch >
Component Information > Locations
Brake Light Switch: Locations
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Brake Light Switch >
Component Information > Locations > Page 9713
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Brake Light Switch >
Component Information > Locations > Page 9714
Brake Light Switch: Service and Repair
The stop light switch has a slip fit in the mounting sleeve which permits positive adjustment by
pulling the brake pedal up firmly against the stop. The pedal arm forces the switch body to slip in
the mounting sleeve bushing to position the switch properly.
1. Disconnect wires from switch and remove switch from bracket. 2. Position replacement switch in
bracket and push inward until fully seated. Brake pedal arm moves switch to correct distance on
rebound. Check if
pedal is in full return position by lifting slightly by hand.
3. Connect switch electrical connector.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front
LH Side Of Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 9719
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 9720
Door Switch: Locations Door Jamb Switch, RH Front
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 9721
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Door Switch >
Component Information > Locations > Door Jamb Switch, LH Front > Page 9722
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Dimmer
Switch > Component Information > Locations
Upper LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector
Twilight Sentinel Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector > Page 9730
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector > Page 9731
Headlamp Switch: Locations Twilight Sentinel/Daytime Running Lamps Harness
Back View Of RH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Twilight Sentinel Connector > Page 9732
Center Of Instrument Panel Wiring
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Page 9733
Headlamp Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Headlamp Switch >
Component Information > Locations > Page 9734
Headlamp Switch: Service and Repair
Fig. 7 Headlamp Switch Replacement
1. Disconnect battery ground cable. 2. Remove lower steering column trim panel attaching screws,
then pull downward to remove. 3. Through glove compartment, unsnap righthand molding. 4.
Loosen steering column support bracket to instrument panel carrier attaching bolts. Do not remove
bolts. 5. Gently lower steering column assembly. Use extreme care when lowering steering to
prevent damage to column assembly. 6. Remove lefthand trim plate to instrument panel carrier
assembly six attaching screws, then unsnap lefthand trim assembly. 7. Remove headlamp switch
attaching screws. 8. Pull switch rearward, then disconnect switch electrical connectors and remove,
Fig. 7. 9. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Horn Switch >
Component Information > Locations
Steering Wheel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Trunk Lamp Switch >
Component Information > Locations > Rear Compartment Lid Latch Switch
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Trunk Lamp Switch >
Component Information > Locations > Rear Compartment Lid Latch Switch > Page 9742
Rear Luggage Compartment With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Trunk Lamp Switch >
Component Information > Locations > Rear Compartment Lid Latch Switch > Page 9743
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations
Turn Signal Switch: Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 9747
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 9748
C210: Turn Signal Switch Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 9749
Turn Signal Switch: Service and Repair
Fig. 9 Lock Plate Retaining Ring Removal
Fig. 10 Turn Signal Electrical Connector & Wiring Isolation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Sensors and Switches - Lighting and Horns > Turn Signal Switch >
Component Information > Locations > Page 9750
Fig. 11 Turn Signal Switch Removal From Column Bowl
Fig. 12 Turn Signal Switch Replacement
1. Disconnect battery cable, then remove steering wheel and column to instrument panel trim
cover. 2. On models with telescoping column, remove bumper spacer and snap ring retainer. 3. On
models less telescoping column, remove cover from lock plate. 4. On all models, using a suitable
tool, compress lock plate (horn contact carrier on tilt models) and remove snap ring (C-ring on tilt
models), Fig. 9. 5. Remove lock plate, cancelling cam, upper bearing preload spring, thrust washer
and signal lever. 6. Remove turn signal lever or actuating arm screw, if equipped, or on models
with column mounted wiper switch, pull lever straight out of detent.
Depress hazard warning button, then unscrew button.
7. Pull connector from bracket and wrap upper part of connector with tape to prevent snagging
wires during removal, Fig. 10. 8. On Tilt models, position shifter housing in Low position. Remove
harness cover. 9. On models less tilt remove retaining screws and remove switch, Fig. 11 AND 12.
10. Reverse procedure to install
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Technical Service Bulletins >
Lighting - Exterior Lamp Condensation and Replacement
Tail Lamp: Technical Service Bulletins Lighting - Exterior Lamp Condensation and Replacement
INFORMATION
Bulletin No.: 01-08-42-001H
Date: January 05, 2011
Subject: Exterior Lamp Condensation and Replacement Guidelines
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn)
Supercede: This bulletin is being revised to add the 2011 model year. Please discard Corporate
Bulletin Number 01-08-42-001G (Section 08 - Body and Accessories).
The following information is being provided to better define the causes of condensation in exterior
lamps and includes guidelines for determining the difference between a lamp with a normal
atmospheric condition (condensation) and a lamp with a water leak.
Some exterior lamps, such as cornering, turn signal, backup, headlamps or tail lamps may exhibit
very small droplets of water, a fine mist or white fog (condensation) on the inside of the lamp lens.
This may be more noticeable on lamps with "multi-lens" designs and may be normal during certain
weather conditions.
Condensation occurs when the air inside the lamp assembly, through atmospheric changes,
reaches the "dew point". When this takes place, the moisture in the air within the lamp assembly
condenses, creating a fine mist or white fog on the inside surface of the lamp lens.
Most exterior lamps on General Motors vehicles use a vented design and feature a replaceable
bulb assembly. They are designed to remove any accumulated moisture vapor by expelling it
through a vent system. The vent system operates at all times, however, it is most effective when
the lamps are ON or when the vehicle is in motion. Depending on the size, shape and location of
the lamp on the vehicle, and the atmospheric conditions occurring, the amount of time required to
clear the lamp may vary from 2 to 6 hours.
Completely sealed headlamp assemblies (sealed beams) are still used on a limited number of
models being manufactured today. These lamps require the replacement of the complete lamp
assembly if a bulb filament burns out.
Condensation 2006 TrailBlazer Shown
A Fine Mist or White Fog on the Inside Surface of the Lamp Lens Occurring After a Period of High
Humidity
- May be located primarily in the lens corners (near the vents) and SHOULD NOT cover more than
half the lens surface.
- The condition should clear of moisture when the vehicle is parked in a dry environment, or when
the vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a SIMILAR
performance.
If the above conditions are noted, the customer should be advised that replacement of a lamp
assembly may not correct this condition.
Water Leak New Style Pickup Shown
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Technical Service Bulletins >
Lighting - Exterior Lamp Condensation and Replacement > Page 9755
Numerous & Various Size Drops of Water Collecting on the Inside Surface of the Lamp Lens After
the Vehicle Has Been Exposed to Rain or a Car Washing Environment
- A condition that covers more than half the surface of the lamp lens.
- An accumulation of water in the bottom of the lamp assembly.
- A condition that WON'T clear when the vehicle is parked in a dry environment, or when the
vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a different
performance.
Any of the above conditions would indicate the need to service the lens or lamp assembly.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9758
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9759
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9760
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9761
Tail Lamp: Locations
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9762
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9763
Rear Lamps
LH Taillamp Harness (Wagon)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9764
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Locations >
Tail/Turn/Stoplamp, Lower > Page 9765
Rear Lamps
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions
Tail Lamp: Diagram Information and Instructions
Abbreviation
A/C Air Conditioning
CCM Central Control Module
CKT Circuit
CONN
Connector
EBCM Electronic Brake Control Module
EBTCM Electronic Brake and Traction Control Module
ECM Engine Control Module
HARN Harness
I/P Instrument Panel
LH Left Hand
PCM Powertrain Control Module
RH Right Hand
TERM Terminal
Body Part Names
Cell References
CELL REFERENCES
General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These
references are used in the Original Equipment Manual to refer to a section in the manual and not a
specific diagram(s).
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9768
GM Sample Diagram W/ Cell Reference
For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a
reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control
section of the manual.
To navigate through these "Cell" references start at the vehicle level and go to: Diagrams /
Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the
system you are working on and view those diagrams.
Note: If unsure of the system - try utilizing the search feature. Type a component in the search
feature that belongs to the system and when the results are displayed note the path displayed. This
will show the system the component belongs in.
Electrostatic Discharge (ESD Sensitive Devices)
All Electrostatic Discharge (ESD) sensitive components are Solid State and the following
information applies to them.
ESD Symbol
Typical Schematic
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9769
The ESD symbol is used on schematics to indicate which components are ESD sensitive. When
handling any electronic part, the service technician should follow the guidelines below to reduce
any possible electrostatic charge build-up on the service technician's body and inadvertent
discharge to the electronic part. If it is not known whether or not a component is ESD sensitive,
assume it is susceptible.
Handling Procedures 1. Always touch a known good ground before handling the part. This should
be repeated while handling the pan and more frequently after sliding
across a seat, sitting down from a standing position or walking a distance.
2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic
procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a
part from its protective package until it is time to install the part. 5. Before removing the part from its
package, ground the package to a known good ground on the vehicle.
Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not
troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a
written diagnostic procedure. Due to the simplification of the schematics, resistance measurements
could be misleading, or could lead to electrostatic discharge.
Schematic Symbols
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9770
Fig.1-Symbols (Part 1 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9771
Fig.2-Symbols (Part 2 Of 3)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9772
Fig.3-Symbols (Part 3 Of 3)
Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between
two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the
shaft is pushed all the way out by a spring.
Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum,
the motor is in the center "at rest" position.
Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating
arm at any position between fully extended and fully retracted. The servo is operated by a control
valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the
greater the retraction of the motor arm. Servo Motors work like the two position motors; the only
difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a
calibrated control.
Supplemental Inflatable Restraint (SIR) System
SIR Symbol
The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to
the following important caution.
CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat
Belts before performing service on or around SIR components or wiring. Failure to follow
CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded
SIR system repairs.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9773
Wire Color Code Identification
Black: BLK
Blue: BLU
Brown: BRN
Grey: GR Or GRY
Green: GRN
Natural: NAT
Orange: ORN
Pink: PNK
Purple: PPL
Red: RED
Tan: TAN
White: WHT
Yellow: YEL
Dark: DK (example: DK GRN same as Dark Green)
Light: LT (example: LT BLU same as Light Blue)
Wire Size Conversion Table
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9774
Tail Lamp: Diagnostic Aids
Additional Information
NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to
prevent false readings or damage to the meter. Do not use the meter to measure resistance
through a solid state module.
Continuity tests that work well for detecting intermittent shorts to ground can be performed by
setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be
heard whenever the meter detects continuity for at least 1 millisecond.
The J 39200 Instruction Manual is a good source of information and should be read thoroughly
upon receipt of the meter as well as kept on hand for reference during new procedures.
Basic Knowledge Required
Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures
contained in this section. You should understand the basic theory of electricity and know the
meaning of voltage, current (amps) and resistance (ohms). You should understand what happens
in a circuit with an open or a shorted wire. You should be able to read and understand a wiring
diagram. The following four-step troubleshooting procedure is recommended:
Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time
fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the
possible causes.
Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you
do not understand how the circuit should work. Check circuits that share wiring with the problem
circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details
and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the
shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If
several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty.
Step 3: Find the fault and repair ^
Narrow down the possible causes.
^ Use the Troubleshooting Hints.
^ Make the necessary measurements or checks as given in the System Diagnosis.
^ Before replacing a component, check power, signal and ground wires at the component harness
connector. If the checks and connections are OK, the most probable cause is component failure.
Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and
that no other faults were induced during the repair.
EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work.
Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams
operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam
operates.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9775
Typical Headlights Schematic
Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor.
Remember, it is essential to understand how a circuit should work, before trying to figure out why it
doesn't.
After you understand how the circuit should operate, read the schematic again, this time keeping in
mind what you have learned by operating the circuit.
Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of
the Headlight Dimmer Switch, terminal "IE" of C100, the TAN wires and grounds G1O5 and G109
are all good.
Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer
Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT
GRN wire between the Headlight Dimmer Switch and C100 are good.
At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in
HI. However, it is extremely unlikely that the HI beam filaments have burned out in both
headlamps, or that both headlamps connections are bad. The cause must be a bad connection at
C100, or a break in the LT GRN wire between C100 and the RH Headlamp.
You have quickly narrowed the possible causes down to one specific area, and have done
absolutely no work on the vehicle itself.
Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure,
you can quickly find C100 and the LT GRN wire, locate the exact trouble point and make the repair.
Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course,
means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working.
Now suppose that the symptoms were different. You may have operated the Headlamps and found
that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were
working. Looking at the schematic, you might conclude that it is unlikely that both HI beam
filaments and the HI Beam Indicator have all burned out at once. The cause is probably the
Headlight Dimmer Switch or its connector.
Checking Terminal Contacts
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9776
DESCRIPTION
When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals
(refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to
check terminal contact between a connector and component, or between in-line connectors, before
replacing a suspect component.
Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating
terminals must be inspected to assure good terminal contact. A poor connection between the male
and female terminal at a connector may be the result of contamination or deformation.
Contamination is caused by the connector halves being improperly connected, a missing or
damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and
dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion,
causing an open circuit or intermittently open circuit.
Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9777
Deformation is caused by probing the mating side of a connector terminal without the proper
adapter, improperly joining the connector halves or repeatedly separating and joining the connector
halves. Deformation, usually to the female terminal contact tang, can result in poor terminal
contact, causing an open or intermittently open circuit.
PROCEDURE
Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to
Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination.
Contamination will result in a white or green build-up within the connector body or between
terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or
underbody connector that shows signs of contamination should be replaced in its entirety:
terminals, seals and connector body.
3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention
force of the female terminal in question by
inserting and removing the male terminal to the female terminal in the connector body. Good
terminal contact will require a certain amount of force to separate the terminals.
4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the
retention force of this terminal to the female
terminal in question by joining and separating the male terminal to the good female terminal, and
then joining and separating the male terminal to the female terminal in question. If the retention
force is significantly different between the two female terminals, replace the female terminal in
question (refer to Terminal Repair Kit, J 38125-A).
If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be
driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage
reading when the problem occurs indicates the problem may be in that circuit.
Detecting Electrical Intermittents
PROCEDURE
Use the following procedure to detect intermittent terminal contact or a broken wire with an
intermittent connection inside the insulation.
The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while
recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to
display the average (AVG) value measured.
When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector
(or length of a circuit) which is suspected of having an intermittent connection but is currently
operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector
(still connected) or from one end of a suspect circuit to the other.
This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter
Connections for examples of the various methods for connecting the meter to the circuit. See:
General Troubleshooting Procedures/Meter Connections
2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually
select the voltage range necessary before
proceeding.
3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond
record) and emit a 1/4 second beep. The meter is
now ready to record and will generate an audible tone for any change in voltage. At this point, you
may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur
for at least 1 millisecond.
4. Try to simulate the condition that is potentially causing an intermittent connection, either by
wiggling connections or wiring, test driving or
performing other operations. If an open or resistance is created, a voltage will be present and the
meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause
the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring
is very helpful for narrowing down an intermittent connection.)
Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for
test driving when it may not be possible to monitor the meter.
To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN.
A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an
intermittent open or that resistance exists and should be repaired as necessary.
IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time
allowed to perform a specific procedure. It is the amount of time used to record each snapshot of
information used for calculating "AVG" when in the "MIN MAX" mode.
Intermittents and Poor Connections
Most intermittents are caused by faulty electrical connections or wiring, although occasionally a
sticking relay or solenoid can be a problem. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material
which could impede proper terminal contact.
^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining
proper terminal orientation with the component or mating connector.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be
checked carefully to ensure good contact tension. Use a corresponding mating terminal to check
for proper tension. Refer to Checking Terminal Contact for the specific procedure.
^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure
requests checking or probing a terminal. Using the adapter will ensure that no damage to the
terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact
tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting
Procedures/Checking Terminal Contacts
^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor
crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the
wire-to-terminal contact area, etc.
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^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches
other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good
circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI.
To avoid any of the above problems when making wiring or terminal repairs, always follow the
instructions for wiring and terminal repair outlined under the Repair Procedures. See: Wire Repair
Procedures/Typical Electrical Repair Procedures
Meter Connections
The previous diagnostic procedure was written to detect intermittents using the meter set to
voltage. Whether using the current, voltage or resistance setting to detect intermittents, it is
necessary to connect the meter to the circuit.
Following are examples of the various methods of connecting the meter to the circuit to be
checked:
^ Backprobe both ends of the connector and either hold the leads in place while manipulating the
connector or tape the leads to the harness for continuous monitoring while performing other
operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.)
^ Disconnect the harness at both ends of the suspect circuit where it connects either to a
component or to other harnesses.
^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit.
^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify
connecting the meter to the circuit or for checking multiple circuits quickly.
Aftermarket Accessories
Always check for aftermarket accessories as the first step in diagnosing electrical problems. If the
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the
cause of the problems.
Some possible causes of vehicle problems related to aftermarket accessories include:
1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver
wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor
connectors on antenna feed line.
Probing (Frontprobe & Backprobe)
After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall
Connector Position Assurance (CPA) and Terminal Position Assurance (TPA).
Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter
from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper
terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact).
Backprobe Only backprobe connector terminals when specifically called for in diagnostic
procedures. Since backprobing can be a source of damage to connector terminals, extra care must
be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by
using too large a test probe.
After backprobing any connector, always check for terminal damage. If terminal damage is
suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General
Troubleshooting Procedures/Checking Terminal Contacts
Testing For Voltage
Voltage Check
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1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM),
be sure the voltmeter's negative lead is
connected to ground.
2. Connect the other lead of the test light or voltmeter to a selected test point (connector or
terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the
voltage reading.
Testing For Continuity
Continuity Check Through A Switch
1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or
ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the
other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an
ohmmeter, LO or no resistance means good continuity.
Testing For Voltage Drop
Voltage Drop Test
This test checks for voltage being lost along a wire, or through a connection or switch.
1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of
the connection or switch) which is closer to the
Battery.
2. Connect the negative lead to the other end of the wire (or the other side of the connection or
switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two
points.
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Testing For Short to Ground
Testing For Short With Self Powered Test Light Or Ohmmeter
WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM)
1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the
fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the
harness from side to side. Continue this at convenient points (about 6 inches apart) while watching
the
test light or DVM.
4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that
point.
Testing For Short With Test Light Or DVM
WITH A SELF-POWERED TEST LIGHT OR OHMMETER.
1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a
self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead
to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side.
Continue this at convenient points (about 6 inches apart) while watching the
self-powered test light or ohmmeter.
5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in
the wiring near that point.
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FUSES POWERING SEVERAL LOADS
1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first
connector or switch leading from the fuse to each load. 3. Replace the fuse.
^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light
or meter as described.
^ If fuse does not blow, refer to next step.
4. Close each connector or switch until the fuse blows in order to find which circuit has the short.
Connect test lamp or meter at the connector to the
suspect circuit (disconnected) rather than at the fuse terminals.
Test Light/Digital Voltmeter
Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with
a pair of leads attached. After grounding one lead, touch the other lead to various points along the
circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being
tested.
A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or
not voltage is present, a DVM indicates how much voltage is present.
An increasing number of circuits include solid state control modules. One example is the Engine
Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or
higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER
use a test light on circuits that contain solid state components, since damage to these components
may result.
When testing for voltage or continuity at the connection, it is not necessary to separate the two
halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector
from the back. Always check both sides of the connector. An accumulation of dirt and corrosion
between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in
checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts
Connector Test Adapters
Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at
separated connectors. This kit contains an assortment of probes which mate with many of the
types of terminals you will see. Avoid using paper clips and other substitutes since they can
damage terminals and cause incorrect measurements.
Self-Powered Test Light
A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a
light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON.
A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds
the circuit you're working on. Select two specific points along the circuit through which there should
be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the
test light circuit will be completed and the bulb will go ON.
NEVER use a self-powered test light on circuits that contain solid state components, since damage
to these components may result.
Ohmmeter
An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much
resistance there is between two points along a circuit. LO resistance means good continuity.
Circuits which include any solid state control modules, such as the Engine Control Module (ECM),
should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200).
When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be
disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure
resistance that the presence of voltages can upset a resistance reading.
Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To
find out if a component is affecting a measurement, take a reading once, reverse the leads and
take a second reading. If the readings differ, the solid state component is affecting the
measurement.
Fused Jumper Wire
A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most
connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not
be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the
circuit being tested.
NOTE: A fused jumper may not protect solid state components from being damaged.
Short Finder
Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a
pulsing magnetic field in the shorted circuit and shows you the location of the short through body
trim or sheet metal.
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Fuse Tester
A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to
the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the
metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if
the fuse is open. The handle of the tester is a tool for removing either type of fuse.
Special Tools
Circuit Breakers
A circuit breaker is a protective device designed to open the circuit when a current load is in excess
of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the
excessive current will open the circuit between the circuit breaker terminals. There are two basic
types of circuit breakers used in GM vehicles: cycling and non-cycling.
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Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive
current passes through it for a period of time. Once the circuit breaker cools, it will close again after
a few seconds. If the cause of the HI current is still present it will open again. It will continue to
cycle open and closed until the condition causing the HI current is removed.
Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is
mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire
within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic
element open until the current source is removed.
The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This
device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive
current passes through it. The excessive current heats the ECB. As it heats, its resistance
increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so
HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing
voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second
or two.
Fuses
Fuse Devices
The most common method of automotive wiring circuit protection is the fuse. A fuse is a device
that, by the melting of its element, opens an electrical circuit when the current exceeds a given
level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a
circuit is overloaded or after a malfunction is repaired.
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Fuse Rating And Color
Fuses are color coded. The standardized color identification and ratings are shown. For service
replacement, non-color coded fuses of the same respective current rating can be used.
Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the
fuse with one of equal current rating.
There are additional specific circuits with in-line fuses. These fuses are located within the individual
wiring harness and will appear to be an open circuit if blown.
Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit
protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly
between the Fuse Block and the system components.
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Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The
Maxifuse is designed to protect cables, normally between the battery and fuse block, from both
direct short circuits and resistive short circuits.
Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an
Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was
designed to be a slower blowing fuse, with less chance of nuisance blows.
Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with
the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and
system components. Since the Minifuse is a smaller device, it allows for more system specific
fusing to be accomplished within the same amount of space as Autofuses.
Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a
replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a
direct short to ground. These elements are easier to service and inspect than a fusible link and will
eventually replace fusible links in all future vehicle applications.
Fusible Links
Good And Damaged Fusible Links
In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like
fuses, fusible links are "one-time" protection devices that will melt and create an open circuit.
Not all fusible link open Circuits can be detected by observation. Always inspect that there is
battery voltage past the fusible link to verify continuity.
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Wire Size Conversion Table
Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the
ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is
designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to
protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are
marked on the insulation with wire-gage size because the heavy insulation makes the link appear
to be a heavier gage than it actually is. The same wire size fusible link must be used when
replacing a blown fusible link.
Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and
Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of
fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty
type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links.
Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links.
Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all
the way through.
- SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of
insulation.
- Expanded Duty: available in all sizes, has an insulation that is one color all the way through and
has three dots following the writing on the insulation. Service fusible links are available in many
lengths.
Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be
cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9
in.).
CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload
protection.
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Single Wire Feed Fusible Link
To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When
connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two
places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures."
Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical
Repair Procedures
Double Wire Feed Fusible Link
To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the
splice. Use two repair links, one spliced to each harness wire.
General Information
The purpose of circuit protection is to protect the wiring assembly during normal and overload
conditions. An overload is defined as a current requirement that is higher than normal. This
overload could be caused by a short circuit or system malfunction. The short circuit could be the
result of a pinched or cut wire or an internal device short circuit, such as an electronic module
failure.
The circuit protection device is only applied to protect the wiring assembly, and not the electrical
load at the end of the assembly. For example, if an electronic component short circuits, the circuit
protection device will assure a minimal amount of damage to the wiring assembly. However, it will
not necessarily prevent damage to the component.
There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link.
Diode Replacement
Many vehicle electrical systems use a diode to isolate circuits and protect the components from
voltage spikes. When installing a new diode, use the following procedure:
Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape.
Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative
diode from the harness with a suitable soldering tool. If the diode is located next to a connector
terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool.
Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered
portion of the wire(s). Do not remove any more than is needed to attach the new diode.
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Diode Identification
Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the
diode with correct bias. Refer the image for replacement diode symbols and current flow
explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink
(aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat.
Follow the manufacturer's instructions for the soldering equipment you are using.
Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step
2.
Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape.
To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode
attachment points.
Acceptable Diode Replacements
In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1
amp, 400 PIV rating can be used for the following applications: ^
A/C Compressor Clutch
^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector
under the carpet at the RH panel)
^ Wiper
^ Charging System (hidden in wire harness)
^ Parking Brake (vehicle with ABS)
^ Relays
^ Solenoids
^ Diesel Glow Plug Circuit
General Information
OPEN CIRCUIT
An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is
open, active components do not energize.
SHORT CIRCUIT
A short circuit is an unwanted connection between one part of the circuit and either ground or
another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open.
Heated Oxygen Sensor (O2S) Repair
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If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen
Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In
order for the sensor to function properly, it must have provided to it a clean air reference. This
clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt
to repair the wires, connectors or terminals could result in the obstruction of the air reference and
degraded Oxygen Sensor performance.
The following guidelines should be used when servicing the Heated Oxygen Sensor:
^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors.
These materials may get into the sensor causing poor performance. Also the sensor pigtail and
harness wires must not be damaged in such a way that the wires inside are exposed. This could
provide a path for foreign materials to enter the sensor and cause performance problems.
^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks,
etc., could block the reference air path through the lead wire.
^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize
the ground wired sensor may rely on this ground as the only ground contact to the sensor.
Removal of the ground wire will also cause poor engine performance.
^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the
vehicle harness connector.
The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit
J 38125-A. Under no circumstances should repairs be soldered since this could result in the air
reference being obstructed.
General Information
^ The following general repair procedures can be used to repair most types of connectors. The
repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather
Pack(R).
^ Use the proper Pick(s) or Tool(s) that apply to the terminal.
^ The Terminal Repair Kit (J 38125-A) contains further information.
Push-to-Seat and Pull-to-Seat Connectors
Typical Push-to-seat Connector And Terminal
Typical Pull-to-seat Connector And Terminal
Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated
with typical connectors. Your connector may differ, but the repair steps are similar. Some
connectors do not require all the steps shown. Skip those that don't apply.
Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain
connectors when mated.
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Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the
terminal from backing out of the connector.
NOTE: The TPA must be removed prior to terminal removal and must be replaced when the
terminal is repaired and reseated.
Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually
molded to the connector.
Step 4: Separate the connector halves and back out seals.
Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this
position.
Step 6: Locate the terminal lock tang in the connector canal.
Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the
connector canal at the mating end of the connector.
Step 8: Depress the locking tang to unseat the terminal. ^
Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector.
^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal
Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was
originally equipped with grease.
Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves.
Weather Pack(R) Connectors
Typical Weather Pack(R) Connector And Terminal
Follow the steps below to repair Weather Pack(R) connectors.
Step 1: Separate the connector halves.
Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to
the connector.
Step 3:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
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Information and Instructions > Page 9791
Grasp the lead and push the terminal to the forward most position. Hold the lead at this position.
Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the
connector cavity until it rests on the cavity shoulder.
Step 5: Gently pull on the lead to remove the terminal through the back of the connector.
NOTE: NEVER use force to remove a terminal from a connector.
Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal
Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs
Step 7: Re-form the lock tang and reseat terminal in connector body.
Step 8: Close secondary locks and join connector halves.
Repairing Short Circuits Caused By Damaged Wire
^ Locate the damaged wire.
^ Find and correct the cause of the wire insulation damage.
^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of
the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing
procedure).
See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using
Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper
Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair
Procedures/Splicing Twisted/Shielded Cable
Splicing Copper Wire Using Crimp and Seal Splice Sleeves
Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to
form a one-to-one splice. They are to be used where there are special requirements such as
moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and
coaxial and may only be used to form a one-to-one splice.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of wire later if you decide to cut more wire to change the location of a splice. You may
have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away
from other splices, harness branches or connectors. This will help prevent moisture from bridging
adjacent splices and causing damage.
Wire Size Conversion Table
Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be
certain to use the same size as the original wire.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9792
To find the correct wire size either find the wire on the schematic and convert the metric size to the
equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the
largest opening in the wire stripper and work down until a clean strip of the insulation is removed.
Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid
nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is
damaged, repeat this procedure after removing the damaged section.
Crimp And Seal Splice Sleeve Chart
Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire
size. The splice sleeves and tool tests are color coded (refer to Chart).
Hand Crimp Tool
Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand
crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the
barrel and the stop.
Seal Splice Sequence
The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the
hand crimper handles slightly to hold the splice sleeve firmly in the proper nest.
Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits
the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles
open when released. The crimper handles will not open until the proper amount of pressure is
applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice.
Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions
that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9793
barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the
insulation. A small amount of sealant will come out of the end of the tubing when sufficient
shrinking is achieved.
Splicing Copper Wire Using Splice Clips
Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose
wire repair device. It may not be acceptable for applications having special requirements such as
moisture sealing.
Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation
damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply
stores). If the harness has a black plastic conduit, simply pull out the desired wire.
Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the
extra length of the wire later if you decide to cut more wire off to change the location of a splice.
You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.)
away from other splices, harness branches or connectors.
Wire Size Conversion Table
Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire
or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire
sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger
than the equivalent metric size.
To find the correct wire size either find the wire on the schematic page and convert the metric size
to the AWG size, or use an AWG wire gage.
If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down
until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the
wires.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9794
Entering The Splice Clip
Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip
size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit.
Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or
large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as
shown. Then, center the splice clip under the stripped wires and hold it in place. ^
Open the crimping tool to its full width and rest one handle on a firm flat surface.
^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point
where the former touches the wings of the clip.
Crimping The Splice Clip
^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until
the crimping tool closes.
^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction.
- No strands of wire are cut loose.
- No insulation is caught under the clip.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9795
Completing The Crimp
Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of
the clip or you may damage or nick the wires.
Applying The Solder
Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the
manufacturer's instruction for the solder equipment you are using.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9796
Proper First Taping
Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice.
Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag
the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the
other wires in the harness.
Proper Second Taping
If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a
winding motion to cover the first piece of tape.
Splicing Twisted/Shielded Cable
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9797
Twisted/shielded Cable
Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For
example, two-conductor cable of this construction is used between the Engine Control Module
(ECM) and the distributor.
Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting
into the drain wire or the mylar tape.
Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be
used to rewrap the twisted conductors after the splices have been made.
The Untwisted Conductors
Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the
splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid
shorts.
Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors
with the mylar tape. Be careful to avoid wrapping the drain wire in the tape.
The Re-assembled Cable
Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain
wire around the conductors and mylar tape.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9798
Proper Taping
Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace
the section of the jacket you removed to make the repair.
Terminal Repairs
Terminal Repair
The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather
Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The
Terminal Repair Kit (J 38125-A) contains further information.
Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for
Weather Pack(R) terminals.
Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation
removal (Weather Pack(R) terminals only).
Step 3: Remove insulation.
Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only).
Step 5: Position strip (and seal for Weather Pack(R)) in terminal.
Step 6: Hand crimp core wings.
Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around
seal and cable (Weather Pack(R)).
Step 8: Solder all hand crimped terminals.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Diagram
Information and Instructions > Page 9799
Tail/Rear Marker/License
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Tail Lamp > Component Information > Diagrams > Page 9800
Tail Lamp: Description and Operation
Voltage is applied at all times from I/P Fuse #31 to the Headlamp Switch and, if equipped, to the
Automatic Headlamp Control or Daytime Running Lamp (DRL) Module from CKT 240. With the
Headlamp Switch in "PARK" or "HEAD" or with low light conditions, if equipped with Twilight
Sentinel, voltage is applied to CKT 9. Current flows through CKT 9, to I/P Fuse Block, which feeds
all Park, Marker, Tail and License Lamps turning them "ON." The only lamps that see a current
from CKT 308 and do not turn "ON," are the turn filaments in the Park/Turn Lamps. They do not
activate because the voltage drop across the Front Side Marker Lamps is much higher than that
across the Turn Lamp Filaments.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Trunk Lamp > Trunk Lamp Switch > Component Information >
Locations > Rear Compartment Lid Latch Switch
Trunk Lid With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Trunk Lamp > Trunk Lamp Switch > Component Information >
Locations > Rear Compartment Lid Latch Switch > Page 9806
Rear Luggage Compartment With Pull-Down
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Trunk Lamp > Trunk Lamp Switch > Component Information >
Locations > Rear Compartment Lid Latch Switch > Page 9807
Back View Of LH Instrument Panel
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Flasher > Component Information >
Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Indicator > Component Information >
Locations
Convenience Center
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Lamp > Component Information >
Technical Service Bulletins > Lighting - Exterior Lamp Condensation and Replacement
Turn Signal Lamp: Technical Service Bulletins Lighting - Exterior Lamp Condensation and
Replacement
INFORMATION
Bulletin No.: 01-08-42-001H
Date: January 05, 2011
Subject: Exterior Lamp Condensation and Replacement Guidelines
Models:
2011 and Prior GM Passenger Cars and Trucks (including Saturn)
Supercede: This bulletin is being revised to add the 2011 model year. Please discard Corporate
Bulletin Number 01-08-42-001G (Section 08 - Body and Accessories).
The following information is being provided to better define the causes of condensation in exterior
lamps and includes guidelines for determining the difference between a lamp with a normal
atmospheric condition (condensation) and a lamp with a water leak.
Some exterior lamps, such as cornering, turn signal, backup, headlamps or tail lamps may exhibit
very small droplets of water, a fine mist or white fog (condensation) on the inside of the lamp lens.
This may be more noticeable on lamps with "multi-lens" designs and may be normal during certain
weather conditions.
Condensation occurs when the air inside the lamp assembly, through atmospheric changes,
reaches the "dew point". When this takes place, the moisture in the air within the lamp assembly
condenses, creating a fine mist or white fog on the inside surface of the lamp lens.
Most exterior lamps on General Motors vehicles use a vented design and feature a replaceable
bulb assembly. They are designed to remove any accumulated moisture vapor by expelling it
through a vent system. The vent system operates at all times, however, it is most effective when
the lamps are ON or when the vehicle is in motion. Depending on the size, shape and location of
the lamp on the vehicle, and the atmospheric conditions occurring, the amount of time required to
clear the lamp may vary from 2 to 6 hours.
Completely sealed headlamp assemblies (sealed beams) are still used on a limited number of
models being manufactured today. These lamps require the replacement of the complete lamp
assembly if a bulb filament burns out.
Condensation 2006 TrailBlazer Shown
A Fine Mist or White Fog on the Inside Surface of the Lamp Lens Occurring After a Period of High
Humidity
- May be located primarily in the lens corners (near the vents) and SHOULD NOT cover more than
half the lens surface.
- The condition should clear of moisture when the vehicle is parked in a dry environment, or when
the vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a SIMILAR
performance.
If the above conditions are noted, the customer should be advised that replacement of a lamp
assembly may not correct this condition.
Water Leak New Style Pickup Shown
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Lamp > Component Information >
Technical Service Bulletins > Lighting - Exterior Lamp Condensation and Replacement > Page 9819
Numerous & Various Size Drops of Water Collecting on the Inside Surface of the Lamp Lens After
the Vehicle Has Been Exposed to Rain or a Car Washing Environment
- A condition that covers more than half the surface of the lamp lens.
- An accumulation of water in the bottom of the lamp assembly.
- A condition that WON'T clear when the vehicle is parked in a dry environment, or when the
vehicle is driven with the lights ON.
- A comparison of the equivalent lamp on the opposing side of the vehicle indicates a different
performance.
Any of the above conditions would indicate the need to service the lens or lamp assembly.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Lamp > Component Information >
Locations > LH
Turn Signal Lamp: Locations LH
LH Rear of Vehicle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Lamp > Component Information >
Locations > LH > Page 9822
Turn Signal Lamp: Locations RH
RH Rear of Vehicle
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Switch > Component Information >
Locations
Turn Signal Switch: Locations
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Switch > Component Information >
Locations > Page 9826
RH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Switch > Component Information >
Locations > Page 9827
C210: Turn Signal Switch Assembly
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Switch > Component Information >
Locations > Page 9828
Turn Signal Switch: Service and Repair
Fig. 9 Lock Plate Retaining Ring Removal
Fig. 10 Turn Signal Electrical Connector & Wiring Isolation
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Turn Signals > Turn Signal Switch > Component Information >
Locations > Page 9829
Fig. 11 Turn Signal Switch Removal From Column Bowl
Fig. 12 Turn Signal Switch Replacement
1. Disconnect battery cable, then remove steering wheel and column to instrument panel trim
cover. 2. On models with telescoping column, remove bumper spacer and snap ring retainer. 3. On
models less telescoping column, remove cover from lock plate. 4. On all models, using a suitable
tool, compress lock plate (horn contact carrier on tilt models) and remove snap ring (C-ring on tilt
models), Fig. 9. 5. Remove lock plate, cancelling cam, upper bearing preload spring, thrust washer
and signal lever. 6. Remove turn signal lever or actuating arm screw, if equipped, or on models
with column mounted wiper switch, pull lever straight out of detent.
Depress hazard warning button, then unscrew button.
7. Pull connector from bracket and wrap upper part of connector with tape to prevent snagging
wires during removal, Fig. 10. 8. On Tilt models, position shifter housing in Low position. Remove
harness cover. 9. On models less tilt remove retaining screws and remove switch, Fig. 11 AND 12.
10. Reverse procedure to install
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Lighting and Horns > Underhood Lamp > Component Information > Locations
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Heated Glass Element > Heated Glass Element Relay > Component
Information > Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Heated Glass Element > Heated Glass Element Relay > Component
Information > Locations > Page 9838
LO Blower Relay, Rear Defog Relay And HI Blower Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Heated Glass Element > Heated Glass Element Switch >
Component Information > Diagrams
Rear Defogger Control Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Rear Defogger > Component Information > Technical Service
Bulletins > A/C - Broken Rear Window Defogger Grid Detection
Rear Defogger: Technical Service Bulletins A/C - Broken Rear Window Defogger Grid Detection
Bulletin No.: 04-08-48-001B
Date: June 28, 2005
INFORMATION
Subject: Rear Window Defogger - Broken Heating Grid Detection Method
Models: 2006 and Prior Passenger Cars and Light Duty Trucks (Including Saturn) 2003-2006
HUMMER H2 2006 HUMMER H3
Supercede:
This bulletin is being revised to add the 2006 model year and additional models. Please discard
Corporate Bulletin Number 04-08-48-001A (Section 08 - Body and Accessories).
The addition of vertical grid lines to the heated back window defogger circuits has made it difficult
to detect broken defogger grid lines. In the past, it was a simple matter to use a voltmeter to check
the continuity of each grid line in order to locate a non-functional line. Some new design back
windows have two vertical grid lines that connect all of the horizontal grid lines together, thereby
providing alternate routes for the electrical current to follow. This makes the old test method
ineffective. If the vehicle does not have the vertical lines, the old (line-by-line) test methods can be
used.
Materials Required
^ Permatex(R) Quick Grid, GM P/N 12346001, or equivalent
^ A small ball of fine steel wool Type 00, or
^ Optional - A strip of liquid crystal heat sensitive paper, 51 mm x 305 mm (2 in x 12 in) or similar
size (Contact Edmund Scientific at 800-728-6999 for part number CR30723-70 or go to
www.scientificsonline.com), or
^ Optional-A portable infrared thermometer, GE-46819, available from Kent-Moore
(1-800-345-2233), or equivalent.
Correction
There are three distinct zones across the back window that must be checked. They are:
^ the driver's side outboard of the two vertical lines
^ the passenger side outboard of the two vertical lines
^ the central zone that falls between the two vertical lines
To detect a broken grid line in any of the above three zones and to isolate the exact location of the
break, perform the following steps:
Caution:
^ Approved safety glasses and gloves should be worn when performing this procedure to reduce
the chance of personal injury.
^ Cover the rear shelf area to prevent damage to the interior trim material.
1. Start the engine and turn on the back window defogger.
2. Take the ball of fine steel wool and twist one end to a point. Move the point slowly across each
grid line. Be sure to start at the far side of the zone and move it to the opposite side of the zone.
When you bridge the grid line break with the steel wool, you will see a small spark. Repeat the test
over the same area to be sure you have accurately located the break. Mark the exact location of
the grid line break. Repeat this portion of the test for each grid line. If you do not see a spark at any
point, it is possible that there are two breaks in the same line and zone. Close visual inspection
using a magnifying glass may be the only way to locate breaks in this case.
3. The following are provided as an alternative way to detect a non-functional grid line. If available,
use in addition to the steel wool.
3.1. Method using liquid crystal heat sensitive paper:
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Rear Defogger > Component Information > Technical Service
Bulletins > A/C - Broken Rear Window Defogger Grid Detection > Page 9846
Important:
The first part of the test must be completed quickly before the entire surface of the back window
becomes warm.
3.1.1. From outside the vehicle, place the heat sensitive paper (dull surface in contact with the
glass) against the top driver side grid line. Start the
engine and turn on the back window defogger. A distinct color change will take place at each
conductive grid line. Repeat for the bottom grid lines until they have all been checked in the driver
side zone.
3.1.2. Repeat the process for the passenger side and center area zones.
3.1.3. If no color change is noted for a grid line, place a crayon or china marker check mark beside
it. Mark each grid line in the zone where it is
non-conductive and, therefore, not heating up. More than one broken grid line may be found.
3.2. Method using portable infrared thermometer:
3.2.1. Start the engine and turn on the rear back window defogger.
3.2.2. From inside the vehicle, start at the top driver side grid line and slowly run the portable
infrared thermometer vertically down the rear
window contacting each grid line. You should be able to see a district variation in temperature
readings.
3.2.3. Mark each grid line in the zone where it is non-conductive and, therefore, not heating up.
More than one broken grid line may be found.
3.2.4. Repeat the process for the passenger side and center area zones.
4. Use Permatex(R) Quick Grid, GM P/N 12346001, or equivalent, to repair each broken grid line.
Follow the manufacturer's instructions.
5. Wait 24 hours before turning the defogger on, or the repair can be fast cured using a heat gun,
260°C - 371°C (500°F - 700°F). Hold the heat gun within 25 - 51 mm (1-2 in) from the repair point
for 2 to 3 minutes.
6. Recheck the grid line with the heat sensitive paper or portable infrared thermometer to ensure
that the line is now functional and that the repair was successful.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Relays and Modules - Windows and Glass > Heated Glass Element
Relay > Component Information > Locations
Plenum View
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Relays and Modules - Windows and Glass > Heated Glass Element
Relay > Component Information > Locations > Page 9851
LO Blower Relay, Rear Defog Relay And HI Blower Relay
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Heated Glass
Element Switch > Component Information > Diagrams
Rear Defogger Control Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Component Locations
Power Window Switch: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Component Locations > Page 9860
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Component Locations > Page 9861
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Component Locations > Page 9862
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Component Locations > Page 9863
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Component Locations > Page 9864
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Sensors and Switches - Windows and Glass > Power Window Switch
> Component Information > Locations > Page 9865
Power Window Switch: Diagrams
Master Power Window Switch Assembly C1 and C2
Power Window Switch LH And RH Rear RH Front
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Motor > Component Information >
Locations > Component Locations
Power Window Motor: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Motor > Component Information >
Locations > Component Locations > Page 9871
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Motor > Component Information >
Locations > Component Locations > Page 9872
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Motor > Component Information >
Locations > Component Locations > Page 9873
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Component Locations
Power Window Switch: Component Locations
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Component Locations > Page 9878
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Component Locations > Page 9879
RH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Component Locations > Page 9880
LH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Component Locations > Page 9881
RH Rear Door And B Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Component Locations > Page 9882
LH Front Door And A Pillar
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Power Window Switch > Component Information >
Locations > Page 9883
Power Window Switch: Diagrams
Master Power Window Switch Assembly C1 and C2
Power Window Switch LH And RH Rear RH Front
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Glass > Back Window Glass > Component
Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information
Back Window Glass: Technical Service Bulletins Body - Vehicle Glass Distortion Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Glass > Front Corner Window Glass >
Component Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information
Front Corner Window Glass: Technical Service Bulletins Body - Vehicle Glass Distortion
Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Glass > Front Door Window Glass > System
Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information
Front Door Window Glass: Technical Service Bulletins Body - Vehicle Glass Distortion Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Glass > Front Door Window Glass > System
Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information > Page 9897
Front Door Window Glass: Technical Service Bulletins Body - Side Window Chipping Information
INFORMATION
Bulletin No.: 06-08-64-001B
Date: October 20, 2009
Subject: Information on Side Door Window Glass Chipping Caused by Hanging Vehicle Key Lock
Box
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3
2009 and Prior Saab 9-7X
Supercede: This bulletin is being revised to add vehicles and model years and to include all types of
door window glass. Please discard Corporate Bulletin Number 06-08-64-001A (Section 08 - Body &
Accessories).
- In several warranty parts review cases, side door window glass was observed with a chip or chips
on the top side of the window glass. Dealer contacts confirmed that they use a vehicle key lock box
on the front side door window glass.
- A random selection of side door glass returns will be conducted to confirm adherence. If a side
door glass is discovered with a chip or chips in the location previously described, the side door
glass will be returned to the dealership for debit.
Example of Side Door Glass
- DO NOT place a vehicle key lock box on a side door window glass.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Glass > Front Door Window Glass > System
Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information > Page 9898
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Glass > Quarter Window Glass > Component
Information > Technical Service Bulletins > Body - Vehicle Glass Distortion Information
Quarter Window Glass: Technical Service Bulletins Body - Vehicle Glass Distortion Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Handle > Component Information > Technical
Service Bulletins > Rear Door Window/Handle - Revised Service Procedure
Technical Service Bulletin # 631038 Date: 960801
Rear Door Window/Handle - Revised Service Procedure
File In Section: 10 - Body
Bulletin No.: 63-10-38
Date: August, 1996
SERVICE MANUAL UPDATE
Subject: Revised Service Procedures for Rear Door Window Regulator and Rear Door Outside
Handle
Models: 1994-96 Chevrolet Caprice, Impala SS
This bulletin is being issued to revise information for the rear door window regulator and rear door
outside handle service procedures in Section 10-6 of the Service Manual.
To service the rear door window regulator, it is necessary to remove the door armrest support,
which is not mentioned in the Service Manual. To service the rear door outside handle, it is
necessary to remove the door armrest support and the locking system module which is not
mentioned in the Service Manual. Listed below are the updated procedures for each component.
Important:
The following labor times have been updated to reflect the revised procedures:
Labor Labor
Operation Description Time
B4520/21 Rear Door Outside Handle 1.0 hr
C0380/81 Rear Door Manual Window 1.3 hrs
Regulator
C0382/83 Rear Door Power Window 1.3 hrs
Regulator
Rear Door Window Regulator
Remove or Disconnect
1. Rear side door trim. Refer to "Rear Side Door Trim".
2. Rear side door armrest support by drilling out rivets.
3. Rear side door water deflector by peeling away from door.
Caution:
Tape rear side door window to rear side door frame. If rear side door window drops into rear side
door personal injury or rear side door window damage may result.
4. Support rear side door window in the position needed to access regulator-to-window sash rivets,
by taping window to door frame using a cloth backed tape.
5. Rear side door locking system module. Refer to "Rear Side Door Locking Module".
6. Rear side door window regulator-to-window sash rivets using a 5/16 inch drill bit.
7. Bolts securing regulator cam to door inner panel.
8. Window regulator electrical connector, if power window regulator.
9. Window regulator-to-door rivets.
10. Window regulator reinforcement, if manual window regulator.
11. Window regulator from door.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Handle > Component Information > Technical
Service Bulletins > Rear Door Window/Handle - Revised Service Procedure > Page 9907
^ The window regulator and motor are serviced as a unit.
Install or Connect
1. Window regulator to door.
2. Window regulator reinforcement, if manual window regulator.
3. Window regulator-to-door rivets.
4. Window regulator electrical connector, if power window regulator.
5. Bolts securing window regulator cam to door inner panel.
6. Rear side door window regulator-to-sash rivets.
7. Rear side door locking system module. Refer to "Rear Side Door Locking System Module".
8. Remove tape securing window to door frame.
9. Rear side door water deflector.
10. Armrest support and rivets.
11. Rear side door trim. Refer to "Rear Side Door Trim".
Rear Side Door Outside Handle
Remove or Disconnect
1. Fully raise window.
2. Rear side door trim. Refer to "Rear Side Door Trim".
3. Armrest support by drilling out rivets.
4. Peel back upper edge of water deflector.
5. Rear side door locking system module rivets and screws.
6. Move rear side door locking system module downward and forward until the outside handle rod
is visible through the door lock opening.
7. Disconnect handle rod from handle by inserting a flat bladed tool through the door lock opening
and unclipping retainer.
8. Door locking system module from door.
9. Outside handle nuts.
10. Outside handle from door.
11. Outside handle rod from locking system module.
Install or Connect
1. Outside handle rod to handle using a new retainer.
2. Hold handle in the open position and install into door.
3. Outside handle nuts.
Tighten
Tighten outside handle nuts to 5 N.m (44 lb in.).
4. Door locking system module, screws and rivets. Do not connect outside handle rod at this time.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windows > Window Handle > Component Information > Technical
Service Bulletins > Rear Door Window/Handle - Revised Service Procedure > Page 9908
Tighten
Tighten door locking system module screws to 10 N.m (89 lb in.).
Adjust
Adjust door outside handle rod by holding rod in the full up position and rotating barrel nut until the
barrel nut aligns with the lever on the door lock.
5. Door outside handle rod to locking system module.
6. Water deflector into place.
7. Armrest support and rivets.
8. Rear side door trim. Refer to "Rear Side Door Trim".
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
Customer Interest: > 09-08-48-006 > Sep > 09 > Body - Stain/Film On Windshield Glass Perimeter
Windshield: Customer Interest Body - Stain/Film On Windshield Glass Perimeter
TECHNICAL
Bulletin No.: 09-08-48-006
Date: September 18, 2009
Subject: Clear Stain or Film on Inside Perimeter of Windshield Glass (Clean/Polish Glass)
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn and Saab) 2010 and Prior HUMMER
H2, H3
Condition
Some customers may comment on a clear stain or film on the inside of the windshield glass. This
condition appears along the outer edges of the glass along the top, bottom or A-pillar areas.
Normal glass cleaning procedures will not remove the stain.
Cause
The assembly plant uses a clear sealer/primer on the outer edge of the windshield glass to improve
adhesion to the urethane adhesive that bonds the windshield glass to the vehicle body. Excess
sealer/primer may drip or flow onto the windshield and cause a stain. Once the sealer/primer dries,
it may appear to have etched the glass.
Correction
Note
A "white" type of toothpaste is recommended for this repair. Gel-type toothpaste may provide less
satisfactory results.
Use a small amount of toothpaste on a soft, cotton cloth to polish the stained area. It may be
necessary to wrap the cloth around a paint stir stick or a similar tool to reach the lower corners of
the windshield glass.
After polishing the glass, clean the inside of the windshield glass with a clean, damp, cotton cloth
and verify all of the stain is removed. Do not use any cleaners or solvents - use only clean warm
water.
Warranty Information (excluding Saab U.S. Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use the table.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
Customer Interest: > 09-08-48-006 > Sep > 09 > Body - Stain/Film On Windshield Glass Perimeter > Page 9917
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
Customer Interest: > 09-08-48-002A > Mar > 09 > Body - Marks/Stains on Windshield When Wet
Windshield: Customer Interest Body - Marks/Stains on Windshield When Wet
TECHNICAL
Bulletin No.: 09-08-48-002A
Date: March 19, 2009
Subject: Marks/Stains on Windshield When Wet (Clean Windshield)
Models: 2010 and Prior Passenger Cars and Trucks (Including Saturn and Saab) 2010 and Prior
HUMMER H2, H3
Supercede: This bulletin is being revised to update the models and model years. Please discard
Corporate Bulletin Number 09-08-48-002 (Section 08 - Body and Accessories).
Condition
Some owners may comment that marks/stains appear on the windshield when the windshield is
wet.
Cause
This condition may be caused by contact between the windshield and the vacuum hoses or other
tools used in the assembly process. This contact may leave a residue that creates a water repellent
surface on the glass which, in wet conditions, appear as marks/stains on the surface.
Correction
Important
DO NOT REPLACE THE WINDSHIELD FOR THIS CONDITION.
To clean the windshield, use Eastwood Glass Polishing Compound*. Follow the manufacturer's
directions for product use. Use only hand tools. DO NOT USE POWER TOOLS.
Parts Information
Eastwood Glass Polishing Compound
1-800-343-9353 (for overseas inquiries: +1-610-705-2200)
http://www.eastwoodco.com/
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such items which may be available from
other sources.
Warranty Information
For vehicles repaired under warranty, use the table above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 06-08-43-003C > Feb > 11 > Glass/Body - Windshield Wiper Performance
Windshield: All Technical Service Bulletins Glass/Body - Windshield Wiper Performance
INFORMATION
Bulletin No.: 06-08-43-003C
Date: February 21, 2011
Subject: Windshield Wiper Performance, Cleaning Instructions and Maintenance
Models:
2012 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2010 and Prior Isuzu Medium Duty Trucks 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 and 2012 model year. Please discard
Corporate Bulletin Number 06-08-43-003B (Section 08 - Body and Accessories).
Wiper Concerns
Most concerns about windshield wiper performance are the result of dirty wiper blades, damaged
wiper blades, or worn out blades that are continuing to be used beyond their useful life. Depending
on environmental conditions, wiper blades can have dramatic differences in lifespan. Here are
some tips and guidelines to maximize wiper performance to avoid damage to the blades, and to
avoid unnecessary replacements.
Many wiper blades are being replaced under warranty with reviews showing there is nothing wrong
with the returned blades other than a build-up of dirt. Additionally, advise the customer to review
the information in their Owner Manual.
Inspection and Cleaning
Scheduled Maintenance
- Inspect your wipers rubber blades every 4-6 months or 12,000 km (7,500 mi) for wear, cracking or
contamination.
- Clean the windshield and the rubber wiper blades (using the procedure below) if the blades are
not clearing the glass satisfactorily. If this does not correct the problem, then replace the rubber
elements.
Cleaning Procedure
Important Avoid getting windshield washer fluid on your hands. Wear rubber gloves or avoid direct
contact with washer fluid.
Important Do not use gasoline, kerosene, or petroleum based products to clean wiper blades.
- Clean the rubber blades using a lint free cloth or paper towel soaked with windshield washer fluid
or a mild detergent. You should see significant amounts of dirt being removed on the cloth.
- Be sure to wash the windshield thoroughly when you clean the blades. Bugs, road grime, sap and
a buildup of car wash/wax treatments may additionally cause wiper streaking.
Tip For a larger scale buildup on the windshield, use a non-abrasive cleaner such as Bon-Ami*
(www.faultless.com) cleanser with a wet sponge, being sure to use plenty of water to avoid
scratching the glass. Flush the surface and body panels completely.
Tip For day-to-day exterior glass cleaning and to maintain a streak free appearance, suggest
Vehicle Care Glass Cleaner, P/N 88862560 (in Canada, 992727). This product is an easy to use
foaming cleaner that quickly removes dirt and grime from glass surfaces.
Tip Interior glass should be cleaned with plain, clean water to eliminate any film or haze on the
window and help prevent fogging, a major customer dissatisfier. Refer to Corporate Bulletin
Number 03-00-89-006D for more information. The New Vehicle Pre-Delivery Inspection form also
recommends using plain water to clean interior glass.
*"We believe this material to be reliable. There may be additional manufacturers of such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products or equipment from these firms or any such items which may be available from other
sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 06-08-43-003C > Feb > 11 > Glass/Body - Windshield Wiper Performance
> Page 9927
Avoiding Wiper Damage
The following are major contributors to wiper damage. Some of these you can control and others
are environmental concerns.
- Extremely dusty areas (such as driving on dirt roads) may cause the wipers rubber edge to wear
quickly and unevenly.
- Sand and salt used on roads for increasing winter traction and ice control will cause the wiper
blades to wear quicker. Areas with significant snowfall require more frequent blade replacements.
- Heat and time may cause the rubber blades to take a "permanent set" resulting in the rubber not
flexing and turning over uniformly. This condition may result in streaking and/or unwiped areas.
- Rubber blades are easily cut or torn when using ice scrapers. Likewise pulling blades up off a
frozen windshield can tear the rubber. Exercise caution when clearing ice and snow.
- Using your wipers to "wear through" frost and ice, instead of allowing the defrosters to melt the
ice, can dull, nick or tear the rubber blades.
- Banging wipers on the glass to remove ice and snow may cause the blade to bend, dislodging the
rubber and causing potential scratching of the windshield.
- Ice can form in the pin joints of the wipers, which can cause streaking and unwiped areas. To
remove ice from pin joints, compress the blade and rubber edge with your hand to loosen the
frozen joints. Consider using Winter Blades that have a rubber cover to avoid this condition.
Note
GM does not recommend the use of any spray on/wipe on windshield treatments or washer fluid
additives. The variation in friction that results on the glass from the use of these products causes
wipers to chatter and have premature wear.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 00-08-48-005D > Sep > 10 > Body - Vehicle Glass Distortion Information
Windshield: All Technical Service Bulletins Body - Vehicle Glass Distortion Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 09-08-48-006 > Sep > 09 > Body - Stain/Film On Windshield Glass
Perimeter
Windshield: All Technical Service Bulletins Body - Stain/Film On Windshield Glass Perimeter
TECHNICAL
Bulletin No.: 09-08-48-006
Date: September 18, 2009
Subject: Clear Stain or Film on Inside Perimeter of Windshield Glass (Clean/Polish Glass)
Models:
2010 and Prior Passenger Cars and Trucks (Including Saturn and Saab) 2010 and Prior HUMMER
H2, H3
Condition
Some customers may comment on a clear stain or film on the inside of the windshield glass. This
condition appears along the outer edges of the glass along the top, bottom or A-pillar areas.
Normal glass cleaning procedures will not remove the stain.
Cause
The assembly plant uses a clear sealer/primer on the outer edge of the windshield glass to improve
adhesion to the urethane adhesive that bonds the windshield glass to the vehicle body. Excess
sealer/primer may drip or flow onto the windshield and cause a stain. Once the sealer/primer dries,
it may appear to have etched the glass.
Correction
Note
A "white" type of toothpaste is recommended for this repair. Gel-type toothpaste may provide less
satisfactory results.
Use a small amount of toothpaste on a soft, cotton cloth to polish the stained area. It may be
necessary to wrap the cloth around a paint stir stick or a similar tool to reach the lower corners of
the windshield glass.
After polishing the glass, clean the inside of the windshield glass with a clean, damp, cotton cloth
and verify all of the stain is removed. Do not use any cleaners or solvents - use only clean warm
water.
Warranty Information (excluding Saab U.S. Models)
For vehicles repaired under warranty, use:
Warranty Information (Saab U.S. Models)
For vehicles repaired under warranty, use the table.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 09-08-48-006 > Sep > 09 > Body - Stain/Film On Windshield Glass
Perimeter > Page 9936
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 09-08-48-002A > Mar > 09 > Body - Marks/Stains on Windshield When Wet
Windshield: All Technical Service Bulletins Body - Marks/Stains on Windshield When Wet
TECHNICAL
Bulletin No.: 09-08-48-002A
Date: March 19, 2009
Subject: Marks/Stains on Windshield When Wet (Clean Windshield)
Models: 2010 and Prior Passenger Cars and Trucks (Including Saturn and Saab) 2010 and Prior
HUMMER H2, H3
Supercede: This bulletin is being revised to update the models and model years. Please discard
Corporate Bulletin Number 09-08-48-002 (Section 08 - Body and Accessories).
Condition
Some owners may comment that marks/stains appear on the windshield when the windshield is
wet.
Cause
This condition may be caused by contact between the windshield and the vacuum hoses or other
tools used in the assembly process. This contact may leave a residue that creates a water repellent
surface on the glass which, in wet conditions, appear as marks/stains on the surface.
Correction
Important
DO NOT REPLACE THE WINDSHIELD FOR THIS CONDITION.
To clean the windshield, use Eastwood Glass Polishing Compound*. Follow the manufacturer's
directions for product use. Use only hand tools. DO NOT USE POWER TOOLS.
Parts Information
Eastwood Glass Polishing Compound
1-800-343-9353 (for overseas inquiries: +1-610-705-2200)
http://www.eastwoodco.com/
*We believe this source and their products to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such items which may be available from
other sources.
Warranty Information
For vehicles repaired under warranty, use the table above.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 83-15-16 > Oct > 98 > New Windshield/Glass Urethane Adhesive Caulking
Kit
Windshield: All Technical Service Bulletins New Windshield/Glass Urethane Adhesive Caulking Kit
File In Section: 10 - Body
Bulletin No.: 83-15-16
Date: October, 1998
INFORMATION
Subject: New Windshield and Stationary Glass Urethane Adhesive Caulking Kit
Models: 1990-99 All Passenger Cars and Trucks
As a result of a change from standard viscosity urethane to high-viscosity urethane, a new
Urethane Adhesive Caulking Kit, P/N 12346392, is now available from GMSPO. This kit contains
the "High Viscosity" Urethane Adhesive for thicker and more consistent bead size applications.
When applied properly, this new high viscosity urethane in many instances will eliminate the need
for depth setting blocks or the damming material to control squeeze out. The following is the
contents of the new kit:
Like the standard viscosity urethane contained in kit (P/N 12346284) that it replaces, it is a
one-part, moisture cure product with curing times that vary as a result of changes in either
temperature or humidity.
THE REQUIRED TIME FOR THIS NEW ONE-PART MATERIAL to ensure a safe installation of
stationary glass before returning the vehicle to the customer, IS A MINIMUM OF SIX (6) HOURS
AT 70°F (21°C) AND 30% RELATIVE HUMIDITY.
Alternate equivalent materials for this kit may be available from a local glass repair shop under the
following product numbers:
Other manufacturers of Urethane Adhesive that have documented their ability to meet or exceed
General Motors specification # 3651M (Performance Requirements for Stationary Glass Bonding
Adhesive System Service) are also considered to be equivalent to GM Kit (P/N 12346392).
In previously published Corporate Bulletin Number 73-10-54, increasing customer demands for
faster service have resulted in quicker two-part urethane adhesives to be made available. Essex
Beta Seal U216* (two-part urethane adhesive) also meets the General Motors 3651M Specification
and can be
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 83-15-16 > Oct > 98 > New Windshield/Glass Urethane Adhesive Caulking
Kit > Page 9945
used when the customer demands quicker repair of the vehicle than the above described one-part
product can provide.
This two-part, chemical cure product requires ONE (1) TO ONE-AND-ONE-HALF (1-1/2) HOURS
FOR CURING BEFORE RETURNING THE VEHICLE TO THE CUSTOMER. This two-part product
also requires primers on the glass and pinchweld surfaces. The primers and applicator daubers are
not included with this two-part product and therefore, must be purchased separately. In addition,
this two-part product requires a special applicator (gun) for proper mixing and dispensing of the
adhesive.
Important:
The U216 product is NOT available from GMSPO and must be obtained locally.
* We believe this source and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such products which may be available from
other sources.
When using either of the above described products, make sure to follow the manufacturer's
directions for application and drying times. For information regarding the removal and installation of
stationary glass, consult the appropriate Service Manual.
Parts information
P/N Description
12346392 Urethane Adhesive Caulking Kit
Parts are expected to be available from GMSPO, 10/12/98.
Important:
The previously recommended adhesive kit (P/N 12346284) will no longer be available from
GMSPO once inventory is exhausted.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 72-05-04 > Aug > 97 > Warranty - Guidelines for Claiming Windshield
Replace
Windshield: All Technical Service Bulletins Warranty - Guidelines for Claiming Windshield Replace
File In Section: Warranty Administration
Bulletin No.: 72-05-04
Date: August, 1997
WARRANTY ADMINISTRATION
Subject: Guidelines for Claiming C0034 - Windshield Replacement
Models: 1989-98 Passenger Cars and Light Duty Trucks
The purpose of this bulletin is to provide retail and wholesale service personnel with guidelines for
using the above subject labor operations.
In an effort to understand the windshield replacements, the following two phase approval process is
being implemented. We feel this approach will allow GM to be responsive to repair decisions on
vehicles over 10,000 miles (16,000KMS), while providing you, our dealers, the empowerment to
address customer needs on those cases requiring repairs early in the vehicle's life, under 10,000
miles (16,000KMS).
Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the
following:
^ Windshield replacement on vehicles under 10,000 miles (16,0OOKMS) can only be made after
Service Management inspection, review and approval. This approval must be noted on the repair
order clearly identifying the defect and reason for replacement. This comment must be submitted in
the comment field of the claim for engineering review.
^ Windshield replacement on vehicles over 10,000 miles (16,000KMS) can only be made after
Service Management inspection, review and approval from the divisional service representative.
Vehicles may be required to be held for wholesale inspection. This approval must be noted on the
repair order clearly identifying the defect and reason for replacement. This comment must be
submitted in the comment field of the claim for engineering review. The claim will require wholesale
authorization for payment.
Additional Requirements
^ Windshields replaced must be held for the normal parts retention period and the defect should be
clearly identified on the glass by means of tape and/or a grease pencil.
^ Sublet windshield replacements, like other sublet repairs are to be claimed for actual dealership
cost less any discounts and or allowances offered. Sublet repairs cannot exceed the normal
allowance provided to the dealership had the repair been completed in-house. See your GM Policy
and Procedure Manual for the complete guidelines.
Windshields damaged by normal wear, road hazards, vandalism, or other physical damage are not
eligible for warranty coverage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Technical Service Bulletins for Windshield: > 73-10-54 > May > 97 > Windshield - Two-Part Urethane Adhesive For
Installation
Windshield: All Technical Service Bulletins Windshield - Two-Part Urethane Adhesive For
Installation
File In Section: 10 - Body
Bulletin No.: 73-10-54
Date: May, 1997
INFORMATION
Subject: Two-Part Urethane Adhesive For Windshield Installations
Models: 1997 And Prior Passenger Cars and Trucks (Using Urethane Adhesive To Retain
Windshields)
General Motors passenger cars and trucks use urethane adhesive as a means to retain the
windshield in the body opening. The urethane adhesive is used to bond the windshield in the
opening, increasing vehicle structure.
The current recommended urethane adhesive, GM P/N 12346284, is a one-part moisture cure
product that requires a minimum curing period of 6 hours at room temperature before returning the
vehicle to the customer.
Increasing customer demands for faster service in recent years have resulted in quicker cure
two-part urethane adhesives.
Essex Beta Seal U216* (two-part urethane adhesive) meets the General Motors 3651M
Specification (Performance Requirements for Stationary Glass Bonding Adhesive System Service)
and can be used when the customer demands quicker repair of the vehicle than the current
one-part materials can provide.
Either of these products can be used when glass replacement is performed. The differences
between these products are as follows:
The CURRENT URETHANE ADHESIVE KIT, GM P/N 12346284, IS A ONE-PART ADHESIVE. It
includes the necessary glass and pinchweld primers and is specified in Service Manuals for
General Motors' vehicles. Since this is a "moisture cure" product, the curing time for this one-part
material will vary with changes to either temperature or humidity. The REQUIRED TIME FOR THIS
ONE-PART
MATERIAL to ensure a safe installation of stationary glass before returning the vehicle to the
customer IS A MINIMUM OF SIX (6) HOURS AT 70°F (21°C) AND 30% RELATIVE HUMIDITY.
ESSEX BETA SEAL U216 IS A TWO-PART ADHESIVE MATERIAL THAT PROVIDES FOR A
ONE (1) TO ONE AND ONE HALF (11/2) HOUR CURE BEFORE RETURNING THE VEHICLE TO
THE CUSTOMER. This product also requires primers on the glass and pinchweld surfaces. This
product requires a special applicator for the mixing and dispensing of the adhesive.
When using this (or any) product, make sure to follow the manufacturer's directions for application
and drying times.
Parts Information
Parts are currently available from GMSPO.
* We believe this source and their product to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such products which may be available from
other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 06-08-43-003C > Feb > 11 > Glass/Body - Windshield Wiper Performance
Windshield: All Technical Service Bulletins Glass/Body - Windshield Wiper Performance
INFORMATION
Bulletin No.: 06-08-43-003C
Date: February 21, 2011
Subject: Windshield Wiper Performance, Cleaning Instructions and Maintenance
Models:
2012 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2010 and Prior Isuzu Medium Duty Trucks 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 and 2012 model year. Please discard
Corporate Bulletin Number 06-08-43-003B (Section 08 - Body and Accessories).
Wiper Concerns
Most concerns about windshield wiper performance are the result of dirty wiper blades, damaged
wiper blades, or worn out blades that are continuing to be used beyond their useful life. Depending
on environmental conditions, wiper blades can have dramatic differences in lifespan. Here are
some tips and guidelines to maximize wiper performance to avoid damage to the blades, and to
avoid unnecessary replacements.
Many wiper blades are being replaced under warranty with reviews showing there is nothing wrong
with the returned blades other than a build-up of dirt. Additionally, advise the customer to review
the information in their Owner Manual.
Inspection and Cleaning
Scheduled Maintenance
- Inspect your wipers rubber blades every 4-6 months or 12,000 km (7,500 mi) for wear, cracking or
contamination.
- Clean the windshield and the rubber wiper blades (using the procedure below) if the blades are
not clearing the glass satisfactorily. If this does not correct the problem, then replace the rubber
elements.
Cleaning Procedure
Important Avoid getting windshield washer fluid on your hands. Wear rubber gloves or avoid direct
contact with washer fluid.
Important Do not use gasoline, kerosene, or petroleum based products to clean wiper blades.
- Clean the rubber blades using a lint free cloth or paper towel soaked with windshield washer fluid
or a mild detergent. You should see significant amounts of dirt being removed on the cloth.
- Be sure to wash the windshield thoroughly when you clean the blades. Bugs, road grime, sap and
a buildup of car wash/wax treatments may additionally cause wiper streaking.
Tip For a larger scale buildup on the windshield, use a non-abrasive cleaner such as Bon-Ami*
(www.faultless.com) cleanser with a wet sponge, being sure to use plenty of water to avoid
scratching the glass. Flush the surface and body panels completely.
Tip For day-to-day exterior glass cleaning and to maintain a streak free appearance, suggest
Vehicle Care Glass Cleaner, P/N 88862560 (in Canada, 992727). This product is an easy to use
foaming cleaner that quickly removes dirt and grime from glass surfaces.
Tip Interior glass should be cleaned with plain, clean water to eliminate any film or haze on the
window and help prevent fogging, a major customer dissatisfier. Refer to Corporate Bulletin
Number 03-00-89-006D for more information. The New Vehicle Pre-Delivery Inspection form also
recommends using plain water to clean interior glass.
*"We believe this material to be reliable. There may be additional manufacturers of such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products or equipment from these firms or any such items which may be available from other
sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 06-08-43-003C > Feb > 11 > Glass/Body - Windshield Wiper Performance >
Page 9959
Avoiding Wiper Damage
The following are major contributors to wiper damage. Some of these you can control and others
are environmental concerns.
- Extremely dusty areas (such as driving on dirt roads) may cause the wipers rubber edge to wear
quickly and unevenly.
- Sand and salt used on roads for increasing winter traction and ice control will cause the wiper
blades to wear quicker. Areas with significant snowfall require more frequent blade replacements.
- Heat and time may cause the rubber blades to take a "permanent set" resulting in the rubber not
flexing and turning over uniformly. This condition may result in streaking and/or unwiped areas.
- Rubber blades are easily cut or torn when using ice scrapers. Likewise pulling blades up off a
frozen windshield can tear the rubber. Exercise caution when clearing ice and snow.
- Using your wipers to "wear through" frost and ice, instead of allowing the defrosters to melt the
ice, can dull, nick or tear the rubber blades.
- Banging wipers on the glass to remove ice and snow may cause the blade to bend, dislodging the
rubber and causing potential scratching of the windshield.
- Ice can form in the pin joints of the wipers, which can cause streaking and unwiped areas. To
remove ice from pin joints, compress the blade and rubber edge with your hand to loosen the
frozen joints. Consider using Winter Blades that have a rubber cover to avoid this condition.
Note
GM does not recommend the use of any spray on/wipe on windshield treatments or washer fluid
additives. The variation in friction that results on the glass from the use of these products causes
wipers to chatter and have premature wear.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 00-08-48-005D > Sep > 10 > Body - Vehicle Glass Distortion Information
Windshield: All Technical Service Bulletins Body - Vehicle Glass Distortion Information
INFORMATION
Bulletin No.: 00-08-48-005D
Date: September 10, 2010
Subject: Distortion in Outer Surface of Vehicle Glass
Models:
2011 and Prior GM Passenger Cars and Trucks 2009 and Prior HUMMER H2 2010 and Prior
HUMMER H3 2005-2009 Saab 9-7X 2010 and Prior Saturn
Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin
Number 00-08-48-005C (Section 08 - Body and Accessories).
Distortion in the outer surface of the windshield glass, door glass or backlite glass may appear after
the vehicle has:
- Accumulated some mileage.
- Been frequently washed in automatic car washes, particularly "touchless" car washes.
This distortion may look like a subtle orange peel pattern, or may look like a drip or sag etched into
the surface of the glass.
Some car wash solutions contain a buffered solution of hydrofluoric acid which is used to clean the
glass. This should not cause a problem if used in the correct concentration. However, if not used
correctly, hydrofluoric acid will attack the glass, and over time, will cause visual distortion in the
outer surface of the glass which cannot be removed by scraping or polishing.
If this condition is suspected, look at the area of the windshield under the wipers or below the belt
seal on the side glass. The area of the glass below the wipers or belt seal will not be affected and
what looks like a drip or sag may be apparent at the edge of the wiper or belt seal. You may also
see a line on the glass where the wiper blade or the belt seal contacts the glass.
Important The repair will require replacing the affected glass and is not a result of a defect in
material or workmanship. Therefore, is not covered by New Vehicle Warranty.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 83-15-16 > Oct > 98 > New Windshield/Glass Urethane Adhesive Caulking Kit
Windshield: All Technical Service Bulletins New Windshield/Glass Urethane Adhesive Caulking Kit
File In Section: 10 - Body
Bulletin No.: 83-15-16
Date: October, 1998
INFORMATION
Subject: New Windshield and Stationary Glass Urethane Adhesive Caulking Kit
Models: 1990-99 All Passenger Cars and Trucks
As a result of a change from standard viscosity urethane to high-viscosity urethane, a new
Urethane Adhesive Caulking Kit, P/N 12346392, is now available from GMSPO. This kit contains
the "High Viscosity" Urethane Adhesive for thicker and more consistent bead size applications.
When applied properly, this new high viscosity urethane in many instances will eliminate the need
for depth setting blocks or the damming material to control squeeze out. The following is the
contents of the new kit:
Like the standard viscosity urethane contained in kit (P/N 12346284) that it replaces, it is a
one-part, moisture cure product with curing times that vary as a result of changes in either
temperature or humidity.
THE REQUIRED TIME FOR THIS NEW ONE-PART MATERIAL to ensure a safe installation of
stationary glass before returning the vehicle to the customer, IS A MINIMUM OF SIX (6) HOURS
AT 70°F (21°C) AND 30% RELATIVE HUMIDITY.
Alternate equivalent materials for this kit may be available from a local glass repair shop under the
following product numbers:
Other manufacturers of Urethane Adhesive that have documented their ability to meet or exceed
General Motors specification # 3651M (Performance Requirements for Stationary Glass Bonding
Adhesive System Service) are also considered to be equivalent to GM Kit (P/N 12346392).
In previously published Corporate Bulletin Number 73-10-54, increasing customer demands for
faster service have resulted in quicker two-part urethane adhesives to be made available. Essex
Beta Seal U216* (two-part urethane adhesive) also meets the General Motors 3651M Specification
and can be
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 83-15-16 > Oct > 98 > New Windshield/Glass Urethane Adhesive Caulking Kit
> Page 9968
used when the customer demands quicker repair of the vehicle than the above described one-part
product can provide.
This two-part, chemical cure product requires ONE (1) TO ONE-AND-ONE-HALF (1-1/2) HOURS
FOR CURING BEFORE RETURNING THE VEHICLE TO THE CUSTOMER. This two-part product
also requires primers on the glass and pinchweld surfaces. The primers and applicator daubers are
not included with this two-part product and therefore, must be purchased separately. In addition,
this two-part product requires a special applicator (gun) for proper mixing and dispensing of the
adhesive.
Important:
The U216 product is NOT available from GMSPO and must be obtained locally.
* We believe this source and their products to be reliable. There may be additional manufacturers
of such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such products which may be available from
other sources.
When using either of the above described products, make sure to follow the manufacturer's
directions for application and drying times. For information regarding the removal and installation of
stationary glass, consult the appropriate Service Manual.
Parts information
P/N Description
12346392 Urethane Adhesive Caulking Kit
Parts are expected to be available from GMSPO, 10/12/98.
Important:
The previously recommended adhesive kit (P/N 12346284) will no longer be available from
GMSPO once inventory is exhausted.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 72-05-04 > Aug > 97 > Warranty - Guidelines for Claiming Windshield Replace
Windshield: All Technical Service Bulletins Warranty - Guidelines for Claiming Windshield Replace
File In Section: Warranty Administration
Bulletin No.: 72-05-04
Date: August, 1997
WARRANTY ADMINISTRATION
Subject: Guidelines for Claiming C0034 - Windshield Replacement
Models: 1989-98 Passenger Cars and Light Duty Trucks
The purpose of this bulletin is to provide retail and wholesale service personnel with guidelines for
using the above subject labor operations.
In an effort to understand the windshield replacements, the following two phase approval process is
being implemented. We feel this approach will allow GM to be responsive to repair decisions on
vehicles over 10,000 miles (16,000KMS), while providing you, our dealers, the empowerment to
address customer needs on those cases requiring repairs early in the vehicle's life, under 10,000
miles (16,000KMS).
Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the
following:
^ Windshield replacement on vehicles under 10,000 miles (16,0OOKMS) can only be made after
Service Management inspection, review and approval. This approval must be noted on the repair
order clearly identifying the defect and reason for replacement. This comment must be submitted in
the comment field of the claim for engineering review.
^ Windshield replacement on vehicles over 10,000 miles (16,000KMS) can only be made after
Service Management inspection, review and approval from the divisional service representative.
Vehicles may be required to be held for wholesale inspection. This approval must be noted on the
repair order clearly identifying the defect and reason for replacement. This comment must be
submitted in the comment field of the claim for engineering review. The claim will require wholesale
authorization for payment.
Additional Requirements
^ Windshields replaced must be held for the normal parts retention period and the defect should be
clearly identified on the glass by means of tape and/or a grease pencil.
^ Sublet windshield replacements, like other sublet repairs are to be claimed for actual dealership
cost less any discounts and or allowances offered. Sublet repairs cannot exceed the normal
allowance provided to the dealership had the repair been completed in-house. See your GM Policy
and Procedure Manual for the complete guidelines.
Windshields damaged by normal wear, road hazards, vandalism, or other physical damage are not
eligible for warranty coverage.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Windows and Glass > Windshield > Component Information > Technical Service Bulletins >
All Other Service Bulletins for Windshield: > 73-10-54 > May > 97 > Windshield - Two-Part Urethane Adhesive For
Installation
Windshield: All Technical Service Bulletins Windshield - Two-Part Urethane Adhesive For
Installation
File In Section: 10 - Body
Bulletin No.: 73-10-54
Date: May, 1997
INFORMATION
Subject: Two-Part Urethane Adhesive For Windshield Installations
Models: 1997 And Prior Passenger Cars and Trucks (Using Urethane Adhesive To Retain
Windshields)
General Motors passenger cars and trucks use urethane adhesive as a means to retain the
windshield in the body opening. The urethane adhesive is used to bond the windshield in the
opening, increasing vehicle structure.
The current recommended urethane adhesive, GM P/N 12346284, is a one-part moisture cure
product that requires a minimum curing period of 6 hours at room temperature before returning the
vehicle to the customer.
Increasing customer demands for faster service in recent years have resulted in quicker cure
two-part urethane adhesives.
Essex Beta Seal U216* (two-part urethane adhesive) meets the General Motors 3651M
Specification (Performance Requirements for Stationary Glass Bonding Adhesive System Service)
and can be used when the customer demands quicker repair of the vehicle than the current
one-part materials can provide.
Either of these products can be used when glass replacement is performed. The differences
between these products are as follows:
The CURRENT URETHANE ADHESIVE KIT, GM P/N 12346284, IS A ONE-PART ADHESIVE. It
includes the necessary glass and pinchweld primers and is specified in Service Manuals for
General Motors' vehicles. Since this is a "moisture cure" product, the curing time for this one-part
material will vary with changes to either temperature or humidity. The REQUIRED TIME FOR THIS
ONE-PART
MATERIAL to ensure a safe installation of stationary glass before returning the vehicle to the
customer IS A MINIMUM OF SIX (6) HOURS AT 70°F (21°C) AND 30% RELATIVE HUMIDITY.
ESSEX BETA SEAL U216 IS A TWO-PART ADHESIVE MATERIAL THAT PROVIDES FOR A
ONE (1) TO ONE AND ONE HALF (11/2) HOUR CURE BEFORE RETURNING THE VEHICLE TO
THE CUSTOMER. This product also requires primers on the glass and pinchweld surfaces. This
product requires a special applicator for the mixing and dispensing of the adhesive.
When using this (or any) product, make sure to follow the manufacturer's directions for application
and drying times.
Parts Information
Parts are currently available from GMSPO.
* We believe this source and their product to be reliable. There may be additional manufacturers of
such products. General Motors does not endorse, indicate any preference for or assume any
responsibility for the products from this firm or for any such products which may be available from
other sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems >
Washer Fluid Level Switch > Component Information > Locations
LH Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems >
Windshield Washer Switch > Component Information > Locations > Component Locations
Windshield Washer Switch: Component Locations
Upper LH Side Of Steering Column
LH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems >
Windshield Washer Switch > Component Information > Locations > Component Locations > Page 9986
Windshield Washer Switch: Connector Locations
Lower LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems >
Windshield Washer Switch > Component Information > Locations > Component Locations > Page 9987
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems >
Windshield Washer Switch > Component Information > Locations > Page 9988
C216: Windshield Wiper/Washer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Component Locations
Wiper Switch: Component Locations
Upper LH Side Of Steering Column
LH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Component Locations > Page 9993
Wiper Switch: Connector Locations
Lower LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Component Locations > Page 9994
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Page 9995
C216: Windshield Wiper/Washer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Page 9996
Wiper Switch: Service and Repair
Fig. 18 Windshield Wiper Switch. Standard Steering Column
Fig. 19 Windshield Wiper Switch. Tilt Steering Column
Fig. 20 Windshield Wiper Switch Actuator Pivot Pin Replacement
1. Disconnect battery ground cable and remove turn signal switch as outlined under Turn Signal
Switch, Service and Repair. See: Lighting and
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Sensors and Switches - Wiper and Washer Systems > Wiper
Switch > Component Information > Locations > Page 9997
Horns/Sensors and Switches - Lighting and Horns/Turn Signal Switch/Service and Repair
2. Remove ignition lock, ignition switch and dimmer switch as outlined under Ignition Lock, Ignition
Switch and Dimmer Switch Service and
Repair. See: Steering and Suspension/Steering/Steering Column/Service and Repair
3. Remove ignition lock housing retaining screws and housing, Fig.18 and 19.. 4. Remove pivot
bolt and wiper switch from lock housing, Fig. 20. 5. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Washer Fluid Level Indicator > Component Information >
Description and Operation
Washer Fluid Level Indicator: Description and Operation
The windshield washer solvent tank has a switch that closes when the washer solvent level
becomes low, illuminating the Low Washer Fluid indicator.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Washer Fluid Level Indicator > Component Information >
Testing and Inspection > Low Solvent Indicator on, Solvent Level OK
Washer Fluid Level Indicator: Testing and Inspection Low Solvent Indicator "on", Solvent Level OK
Fig. 95 Chart 4: Low Washer Fluid Indicator On At All Times
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Washer Fluid Level Indicator > Component Information >
Testing and Inspection > Low Solvent Indicator on, Solvent Level OK > Page 10003
Washer Fluid Level Indicator: Testing and Inspection Low Solvent Indicator Inoperative
Fig. 94 Chart 3: Low Washer Fluid Indicator Inoperative
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Washer Fluid Level Switch > Component Information >
Locations
LH Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Motor > Component Information >
Locations
LH Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Motor > Component Information >
Testing and Inspection > Washer Will Not Operate
Windshield Washer Motor: Testing and Inspection Washer Will Not Operate
Fig. 73 Test 8: Washer Will Not Operate.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Motor > Component Information >
Testing and Inspection > Washer Will Not Operate > Page 10012
Windshield Washer Motor: Testing and Inspection Washer Will Not Shut Off
Fig. 74 Test 9: Washer Will Not Shut Off.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Pump > Component Information >
Locations > Wiper Washer Pump Motor, Front
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Pump > Component Information >
Locations > Wiper Washer Pump Motor, Front > Page 10017
LH Front Of Engine
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Reservoir > Component Information >
Locations
Windshield Washer Reservoir: Locations
LH Front Of Engine
Brake Pressure Modulator Valve (With Electronic Brake Control Module)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Switch > Component Information >
Locations > Component Locations
Windshield Washer Switch: Component Locations
Upper LH Side Of Steering Column
LH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Switch > Component Information >
Locations > Component Locations > Page 10025
Windshield Washer Switch: Connector Locations
Lower LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Switch > Component Information >
Locations > Component Locations > Page 10026
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Windshield Washer Switch > Component Information >
Locations > Page 10027
C216: Windshield Wiper/Washer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Blade > Component Information > Technical Service
Bulletins > Glass/Body - Windshield Wiper Performance
Wiper Blade: Technical Service Bulletins Glass/Body - Windshield Wiper Performance
INFORMATION
Bulletin No.: 06-08-43-003C
Date: February 21, 2011
Subject: Windshield Wiper Performance, Cleaning Instructions and Maintenance
Models:
2012 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2,
H3 2010 and Prior Isuzu Medium Duty Trucks 2005-2009 Saab 9-7X
Supercede: This bulletin is being revised to add the 2011 and 2012 model year. Please discard
Corporate Bulletin Number 06-08-43-003B (Section 08 - Body and Accessories).
Wiper Concerns
Most concerns about windshield wiper performance are the result of dirty wiper blades, damaged
wiper blades, or worn out blades that are continuing to be used beyond their useful life. Depending
on environmental conditions, wiper blades can have dramatic differences in lifespan. Here are
some tips and guidelines to maximize wiper performance to avoid damage to the blades, and to
avoid unnecessary replacements.
Many wiper blades are being replaced under warranty with reviews showing there is nothing wrong
with the returned blades other than a build-up of dirt. Additionally, advise the customer to review
the information in their Owner Manual.
Inspection and Cleaning
Scheduled Maintenance
- Inspect your wipers rubber blades every 4-6 months or 12,000 km (7,500 mi) for wear, cracking or
contamination.
- Clean the windshield and the rubber wiper blades (using the procedure below) if the blades are
not clearing the glass satisfactorily. If this does not correct the problem, then replace the rubber
elements.
Cleaning Procedure
Important Avoid getting windshield washer fluid on your hands. Wear rubber gloves or avoid direct
contact with washer fluid.
Important Do not use gasoline, kerosene, or petroleum based products to clean wiper blades.
- Clean the rubber blades using a lint free cloth or paper towel soaked with windshield washer fluid
or a mild detergent. You should see significant amounts of dirt being removed on the cloth.
- Be sure to wash the windshield thoroughly when you clean the blades. Bugs, road grime, sap and
a buildup of car wash/wax treatments may additionally cause wiper streaking.
Tip For a larger scale buildup on the windshield, use a non-abrasive cleaner such as Bon-Ami*
(www.faultless.com) cleanser with a wet sponge, being sure to use plenty of water to avoid
scratching the glass. Flush the surface and body panels completely.
Tip For day-to-day exterior glass cleaning and to maintain a streak free appearance, suggest
Vehicle Care Glass Cleaner, P/N 88862560 (in Canada, 992727). This product is an easy to use
foaming cleaner that quickly removes dirt and grime from glass surfaces.
Tip Interior glass should be cleaned with plain, clean water to eliminate any film or haze on the
window and help prevent fogging, a major customer dissatisfier. Refer to Corporate Bulletin
Number 03-00-89-006D for more information. The New Vehicle Pre-Delivery Inspection form also
recommends using plain water to clean interior glass.
*"We believe this material to be reliable. There may be additional manufacturers of such material.
General Motors does not endorse, indicate any preference for or assume any responsibility for the
products or equipment from these firms or any such items which may be available from other
sources.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Blade > Component Information > Technical Service
Bulletins > Glass/Body - Windshield Wiper Performance > Page 10032
Avoiding Wiper Damage
The following are major contributors to wiper damage. Some of these you can control and others
are environmental concerns.
- Extremely dusty areas (such as driving on dirt roads) may cause the wipers rubber edge to wear
quickly and unevenly.
- Sand and salt used on roads for increasing winter traction and ice control will cause the wiper
blades to wear quicker. Areas with significant snowfall require more frequent blade replacements.
- Heat and time may cause the rubber blades to take a "permanent set" resulting in the rubber not
flexing and turning over uniformly. This condition may result in streaking and/or unwiped areas.
- Rubber blades are easily cut or torn when using ice scrapers. Likewise pulling blades up off a
frozen windshield can tear the rubber. Exercise caution when clearing ice and snow.
- Using your wipers to "wear through" frost and ice, instead of allowing the defrosters to melt the
ice, can dull, nick or tear the rubber blades.
- Banging wipers on the glass to remove ice and snow may cause the blade to bend, dislodging the
rubber and causing potential scratching of the windshield.
- Ice can form in the pin joints of the wipers, which can cause streaking and unwiped areas. To
remove ice from pin joints, compress the blade and rubber edge with your hand to loosen the
frozen joints. Consider using Winter Blades that have a rubber cover to avoid this condition.
Note
GM does not recommend the use of any spray on/wipe on windshield treatments or washer fluid
additives. The variation in friction that results on the glass from the use of these products causes
wipers to chatter and have premature wear.
Disclaimer
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Gear Box > Component Information > Service and
Repair
Wiper Gear Box: Service and Repair
1. Disconnect battery ground cable. 2. Remove right and lefthand wiper arm and hose. 3. Remove
lefthand cowl vent screen, then righthand screen. 4. Disconnect plastic nozzle hose from rubber
washer hose. 5. Remove wiper linkage access hole cover attaching screws, then remove cover. 6.
Disconnect drive link from motor crank arm. 7. Remove linkage to body attaching screws, then
remove linkage through access hole. 8. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Motor > Component Information > Locations
Engine Harness/U/Hood Electrical Center, Right Side
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Motor > Component Information > Locations > Page
10039
Windshield Wiper Motor Assembly (C1)
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Motor > Component Information > Locations > Page
10040
Wiper Motor: Service and Repair
1. Disconnect battery ground cable. 2. Remove righthand wiper arm and hose. 3. Remove lefthand
cowl vent screen, then righthand screen. 4. Remove wiper linkage access hole cover attaching
screws, then remove hole cover. 5. Disconnect wiper motor drive link from motor crank arm. 6.
Disconnect wiper motor electrical connectors. 7. Remove motor attaching bolts, then remove motor
guiding crank arm through access hole. 8. Reverse procedure to install.
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Switch > Component Information > Locations >
Component Locations
Wiper Switch: Component Locations
Upper LH Side Of Steering Column
LH I/P
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Switch > Component Information > Locations >
Component Locations > Page 10045
Wiper Switch: Connector Locations
Lower LH Side Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Switch > Component Information > Locations >
Component Locations > Page 10046
Base Of Steering Column
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Switch > Component Information > Locations > Page
10047
C216: Windshield Wiper/Washer Switch
Chevrolet Impala Ss Workshop Manual (V8-350 5.7L VIN P MFI (1995))
Chevrolet Workshop Manuals > Wiper and Washer Systems > Wiper Switch > Component Information > Locations > Page
10048
Wiper Switch: Service and Repair
Fig. 18 Windshield Wiper Switch. Standard Steering Column
Fig. 19 Windshield Wiper Switch. Tilt Steering Column
Fig. 20 Windshield Wiper Switch Actuator Pivot Pin Replacement
1. Disconnect battery ground cable and remove turn signal switch as outlined under Turn Signal
Switch, Service and Repair. See: Lighting and